Network Working Group Keith McCloghrie Internet Draft Cisco Systems Obsoletes: 1573, 2233 Frank Kastenholz Argon Networks 11 October 1999 The Interfaces Group MIB draft-ietf-ifmib-ifmib2-01.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [RFC2026]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Distribution of this document is unlimited. Please send comments to the Interfaces MIB Working Group at if-mib@vnd.tek.com. Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved. Internet Draft Interfaces Group MIB October 1999 1. Introduction This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it describes managed objects used for managing Network Interfaces. This memo discusses the 'interfaces' group of MIB-II [17], especially the experience gained from the definition of numerous media-specific MIB modules for use in conjunction with the 'interfaces' group for managing various sub- layers beneath the internetwork-layer. It specifies clarifications to, and extensions of, the architectural issues within the MIB-II model of the 'interfaces' group. This memo obsoletes RFCs 1573 and 2233, the previous versions of the Interfaces Group MIB. The key words "MUST" and "MUST NOT" in this document are to be interpreted as described in RFC 2119 [16]. 2. The SNMP Network Management Framework The SNMP Management Framework presently consists of five major components: o An overall architecture, described in RFC 2571 [1]. o Mechanisms for describing and naming objects and events for the purpose of management. The first version of this Structure of Management Information (SMI) is called SMIv1 and described in STD 16/RFC 1155 [2], STD 16/RFC 1212 [3] and RFC 1215 [4]. The second version, called SMIv2, is described in STD 58, which consists of RFC 2578 [5], RFC 2579 [6] and RFC 2580 [7]. o Message protocols for transferring management information. The first version of the SNMP message protocol is called SNMPv1 and described in STD 15/RFC 1157 [8]. A second version of the SNMP message protocol, which is not an Internet standards track protocol, is called SNMPv2c and described in RFC 1901 [9] and RFC 1906 [10]. The third version of the message protocol is called SNMPv3 and described in RFC 1906 [10], RFC 2572 [11] and RFC 2574 [12]. McCloghrie & Kastenholz [Page 2]
Internet Draft Interfaces Group MIB October 1999 o Protocol operations for accessing management information. The first set of protocol operations and associated PDU formats is described in STD 15/RFC 1157 [8]. A second set of protocol operations and associated PDU formats is described in RFC 1905 [13]. o A set of fundamental applications described in RFC 2573 [14] and the view-based access control mechanism described in RFC 2575 [15]. A more detailed introduction to the current SNMP Management Framework can be found in RFC 2570 [22]. Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the mechanisms defined in the SMI. This memo specifies a MIB module that is compliant to the SMIv2. A MIB conforming to the SMIv1 can be produced through the appropriate translations. The resulting translated MIB must be semantically equivalent, except where objects or events are omitted because no translation is possible (e.g., use of Counter64). Some machine readable information in SMIv2 will be converted into textual descriptions in SMIv1 during the translation process. However, this loss of machine readable information is not considered to change the semantics of the MIB. 3. Experience with the Interfaces Group One of the strengths of internetwork-layer protocols such as IP [18] is that they are designed to run over any network interface. In achieving this, IP considers any and all protocols it runs over as a single "network interface" layer. A similar view is taken by other internetwork-layer protocols. This concept is represented in MIB-II by the 'interfaces' group which defines a generic set of managed objects such that any network interface can be managed in an interface-independent manner through these managed objects. The 'interfaces' group provides the means for additional managed objects specific to particular types of network interface (e.g., a specific medium such as Ethernet) to be defined as extensions to the 'interfaces' group for media-specific management. Since the standardization of MIB-II, many such media-specific MIB modules McCloghrie & Kastenholz [Page 3]
Internet Draft Interfaces Group MIB October 1999 have been defined. Experience in defining these media-specific MIB modules has shown that the model defined by MIB-II is too simplistic and/or static for some types of media-specific management. As a result, some of these media-specific MIB modules assume an evolution or loosening of the model. This memo documents and standardizes that evolution of the model and fills in the gaps caused by that evolution. This memo also incorporates the interfaces group extensions documented in RFC 1229 [19]. 3.1. Clarifications/Revisions There are several areas for which experience has indicated that clarification, revision, or extension of the model would be helpful. The following sections discuss the changes in the interfaces group adopted by this memo in each of these areas. In some sections, one or more paragraphs contain discussion of rejected alternatives to the model adopted in this memo. Readers not familiar with the MIB-II model and not interested in the rationale behind the new model may want to skip these paragraphs. 3.1.1. Interface Sub-Layers Experience in defining media-specific management information has shown the need to distinguish between the multiple sub-layers beneath the internetwork-layer. In addition, there is a need to manage these sub-layers in devices (e.g., MAC-layer bridges) which are unaware of which, if any, internetwork protocols run over these sub-layers. As such, a model of having a single conceptual row in the interfaces table (MIB-II's ifTable) represent a whole interface underneath the internetwork-layer, and having a single associated media-specific MIB module (referenced via the ifType object) is too simplistic. A further problem arises with the value of the ifType object which has enumerated values for each type of interface. Consider, for example, an interface with PPP running over an HDLC link which uses a RS232-like connector. Each of these sub-layers has its own media-specific MIB module. If all of this is represented by a single conceptual row in the ifTable, then an enumerated value for ifType is needed for that specific combination which maps to the specific combination of media- specific MIBs. Furthermore, such a model still lacks a method to McCloghrie & Kastenholz [Page 4]
Internet Draft Interfaces Group MIB October 1999 describe the relationship of all the sub-layers of the MIB stack. An associated problem is that of upward and downward multiplexing of the sub-layers. An example of upward multiplexing is MLP (Multi-Link-Procedure) which provides load-sharing over several serial lines by appearing as a single point-to-point link to the sub-layer(s) above. An example of downward multiplexing would be several instances of PPP, each framed within a separate X.25 virtual circuit, all of which run over one fractional T1 channel, concurrently with other uses of the T1 link. The MIB structure must allow these sorts of relationships to be described. Several solutions for representing multiple sub-layers were rejected. One was to retain the concept of one conceptual row for all the sub-layers of an interface and have each media-specific MIB module identify its "superior" and "subordinate" sub-layers through OBJECT IDENTIFIER "pointers". This scheme would have several drawbacks: the superior/subordinate pointers would be contained in the media-specific MIB modules; thus, a manager could not learn the structure of an interface without inspecting multiple pointers in different MIB modules; this would be overly complex and only possible if the manager had knowledge of all the relevant media-specific MIB modules; MIB modules would all need to be retrofitted with these new "pointers"; this scheme would not adequately address the problem of upward and downward multiplexing; and finally, enumerated values of ifType would be needed for each combination of sub-layers. Another rejected solution also retained the concept of one conceptual row for all the sub-layers of an interface but had a new separate MIB table to identify the "superior" and "subordinate" sub-layers and to contain OBJECT IDENTIFIER "pointers" to the media-specific MIB module for each sub-layer. Effectively, one conceptual row in the ifTable would represent each combination of sub-layers between the internetwork-layer and the wire. While this scheme has fewer drawbacks, it still would not support downward multiplexing, such as PPP over MLP: observe that MLP makes two (or more) serial lines appear to the layers above as a single physical interface, and thus PPP over MLP should appear to the internetwork-layer as a single interface; in contrast, this scheme would result in two (or more) conceptual rows in the ifTable, both of which the internetwork-layer would run over. This scheme would also require enumerated values of ifType for each combination of sub-layers. The solution adopted by this memo is to have an individual conceptual row in the ifTable to represent each sub-layer, and McCloghrie & Kastenholz [Page 5]
Internet Draft Interfaces Group MIB October 1999 have a new separate MIB table (the ifStackTable, see section 6 below) to identify the "superior" and "subordinate" sub-layers through INTEGER "pointers" to the appropriate conceptual rows in the ifTable. This solution supports both upward and downward multiplexing, allows the IANAifType to Media-Specific MIB mapping to identify the media-specific MIB module for that sub-layer, such that the new table need only be referenced to obtain information about layering, and it only requires enumerated values of ifType for each sub-layer, not for combinations of them. However, it does require that the descriptions of some objects in the ifTable (specifically, ifType, ifPhysAddress, ifInUcastPkts, and ifOutUcastPkts) be generalized so as to apply to any sub-layer (rather than only to a sub-layer immediately beneath the network layer as previously), plus some (specifically, ifSpeed) which need to have appropriate values identified for use when a generalized definition does not apply to a particular sub-layer. In addition, this adopted solution makes no requirement that a device, in which a sub-layer is instrumented by a conceptual row of the ifTable, be aware of whether an internetwork protocol runs on top of (i.e., at some layer above) that sub-layer. In fact, the counters of packets received on an interface are defined as counting the number "delivered to a higher-layer protocol". This meaning of "higher-layer" includes: (1) Delivery to a forwarding module which accepts packets/frames/octets and forwards them on at the same protocol layer. For example, for the purposes of this definition, the forwarding module of a MAC-layer bridge is considered as a "higher-layer" to the MAC-layer of each port on the bridge. (2) Delivery to a higher sub-layer within a interface stack. For example, for the purposes of this definition, if a PPP module operated directly over a serial interface, the PPP module would be considered the higher sub-layer to the serial interface. (3) Delivery to a higher protocol layer which does not do packet forwarding for sub-layers that are "at the top of" the interface stack. For example, for the purposes of this definition, the local IP module would be considered the higher layer to a SLIP serial interface. McCloghrie & Kastenholz [Page 6]
Internet Draft Interfaces Group MIB October 1999 Similarly, for output, the counters of packets transmitted out an interface are defined as counting the number "that higher-level protocols requested to be transmitted". This meaning of "higher- layer" includes: (1) A forwarding module, at the same protocol layer, which transmits packets/frames/octets that were received on an different interface. For example, for the purposes of this definition, the forwarding module of a MAC-layer bridge is considered as a "higher-layer" to the MAC-layer of each port on the bridge. (2) The next higher sub-layer within an interface stack. For example, for the purposes of this definition, if a PPP module operated directly over a serial interface, the PPP module would be a "higher layer" to the serial interface. (3) For sub-layers that are "at the top of" the interface stack, a higher element in the network protocol stack. For example, for the purposes of this definition, the local IP module would be considered the higher layer to an Ethernet interface. 3.1.2. Guidance on Defining Sub-layers The designer of a media-specific MIB must decide whether to divide the interface into sub-layers or not, and if so, how to make the divisions. The following guidance is offered to assist the media- specific MIB designer in these decisions. In general, the number of entries in the ifTable should be kept to the minimum required for network management. In particular, a group of related interfaces should be treated as a single interface with one entry in the ifTable providing that: (1) None of the group of interfaces performs multiplexing for any other interface in the agent, (2) There is a meaningful and useful way for all of the ifTable's information (e.g., the counters, and the status variables), and all of the ifTable's capabilities (e.g., write access to ifAdminStatus), to apply to the group of interfaces as a whole. McCloghrie & Kastenholz [Page 7]
Internet Draft Interfaces Group MIB October 1999 Under these circumstances, there should be one entry in the ifTable for such a group of interfaces, and any internal structure which needs to be represented to network management should be captured in a MIB module specific to the particular type of interface. Note that application of bullet 2 above to the ifTable's ifType object requires that there is a meaningful media-specific MIB and a meaningful ifType value which apply to the group of interfaces as a whole. For example, it is not appropriate to treat an HDLC sub-layer and an RS-232 sub-layer as a single ifTable entry when the media-specific MIBs and the ifType values for HDLC and RS-232 are separate (rather than combined). Subject to the above, it is appropriate to assign an ifIndex value to any interface that can occur in an interface stack (in the ifStackTable) where the bottom of the stack is a physical interface (ifConnectorPresent has the value 'true') and there is a layer-3 or other application that "points down" to the top of this stack. An example of an application that points down to the top of the stack is the Character MIB [21]. Note that the sub-layers of an interface on one device will sometimes be different from the sub-layers of the interconnected interface of another device; for example, for a frame-relay DTE interface connected a frameRelayService interface, the inter- connected DTE and DCE interfaces have different ifType values and media-specific MIBs. These guidelines are just that, guidelines. The designer of a media-specific MIB is free to lay out the MIB in whatever SMI conformant manner is desired. However, in doing so, the media- specific MIB MUST completely specify the sub-layering model used for the MIB, and provide the assumptions, reasoning, and rationale used to develop that model. 3.1.3. Virtual Circuits Several of the sub-layers for which media-specific MIB modules have been defined are connection oriented (e.g., Frame Relay, X.25). Experience has shown that each effort to define such a MIB module revisits the question of whether separate conceptual rows in the ifTable are needed for each virtual circuit. Most, if not all, of these efforts to date have decided to have all virtual circuits reference a single conceptual row in the ifTable. McCloghrie & Kastenholz [Page 8]
Internet Draft Interfaces Group MIB October 1999 This memo strongly recommends that connection-oriented sub-layers do not have a conceptual row in the ifTable for each virtual circuit. This avoids the proliferation of conceptual rows, especially those which have considerable redundant information. (Note, as a comparison, that connection-less sub-layers do not have conceptual rows for each remote address.) There may, however, be circumstances under which it is appropriate for a virtual circuit of a connection-oriented sub-layer to have its own conceptual row in the ifTable; an example of this might be PPP over an X.25 virtual circuit. The MIB in section 6 of this memo supports such circumstances. If a media-specific MIB wishes to assign an entry in the ifTable to each virtual circuit, the MIB designer must present the rationale for this decision in the media-specific MIB's specification. 3.1.4. Bit, Character, and Fixed-Length Interfaces RS-232 is an example of a character-oriented sub-layer over which (e.g., through use of PPP) IP datagrams can be sent. Due to the packet-based nature of many of the objects in the ifTable, experience has shown that it is not appropriate to have a character-oriented sub-layer represented by a whole conceptual row in the ifTable. Experience has also shown that it is sometimes desirable to have some management information for bit-oriented interfaces, which are similarly difficult to represent by a whole conceptual row in the ifTable. For example, to manage the channels of a DS1 circuit, where only some of the channels are carrying packet-based data. A further complication is that some subnetwork technologies transmit data in fixed length transmission units. One example of such a technology is cell relay, and in particular Asynchronous Transfer Mode (ATM), which transmits data in fixed-length cells. Representing such a interface as a packet-based interface produces redundant objects if the relationship between the number of packets and the number of octets in either direction is fixed by the size of the transmission unit (e.g., the size of a cell). About half the objects in the ifTable are applicable to every type of interface: packet-oriented, character-oriented, and bit- oriented. Of the other half, two are applicable to both character-oriented and packet-oriented interfaces, and the rest McCloghrie & Kastenholz [Page 9]
Internet Draft Interfaces Group MIB October 1999 are applicable only to packet-oriented interfaces. Thus, while it is desirable for consistency to be able to represent any/all types of interfaces in the ifTable, it is not possible to implement the full ifTable for bit- and character-oriented sub-layers. A rejected solution to this problem would be to split the ifTable into two (or more) new MIB tables, one of which would contain objects that are relevant only to packet-oriented interfaces (e.g., PPP), and another that may be used by all interfaces. This is highly undesirable since it would require changes in every agent implementing the ifTable (i.e., just about every existing SNMP agent). The solution adopted in this memo builds upon the fact that compliance statements in SNMPv2 (in contrast to SNMPv1) refer to object groups, where object groups are explicitly defined by listing the objects they contain. Thus, in SNMPv2, multiple compliance statements can be specified, one for all interfaces and additional ones for specific types of interfaces. The separate compliance statements can be based on separate object groups, where the object group for all interfaces can contain only those objects from the ifTable which are appropriate for every type of interfaces. Using this solution, every sub-layer can have its own conceptual row in the ifTable. Thus, section 6 of this memo contains definitions of the objects of the existing 'interfaces' group of MIB-II, in a manner which is both SNMPv2-compliant and semantically-equivalent to the existing MIB-II definitions. With equivalent semantics, and with the BER ("on the wire") encodings unchanged, these definitions retain the same OBJECT IDENTIFIER values as assigned by MIB-II. Thus, in general, no rewrite of existing agents which conform to MIB-II and the ifExtensions MIB is required. In addition, this memo defines several object groups for the purposes of defining which objects apply to which types of interface: (1) the ifGeneralInformationGroup. This group contains those objects applicable to all types of network interfaces, including bit-oriented interfaces. (2) the ifPacketGroup. This group contains those objects applicable to packet-oriented network interfaces. McCloghrie & Kastenholz [Page 10]
Internet Draft Interfaces Group MIB October 1999 (3) the ifFixedLengthGroup. This group contains the objects applicable not only to character-oriented interfaces, such as RS-232, but also to those subnetwork technologies, such as cell-relay/ATM, which transmit data in fixed length transmission units. As well as the octet counters, there are also a few other counters (e.g., the error counters) which are useful for this type of interface, but are currently defined as being packet-oriented. To accommodate this, the definitions of these counters are generalized to apply to character-oriented interfaces and fixed-length- transmission interfaces. It should be noted that the octet counters in the ifTable aggregate octet counts for unicast and non-unicast packets into a single octet counter per direction (received/transmitted). Thus, with the above definition of fixed-length-transmission interfaces, where such interfaces which support non-unicast packets, separate counts of unicast and multicast/broadcast transmissions can only be maintained in a media-specific MIB module. 3.1.5. Interface Numbering MIB-II defines an object, ifNumber, whose value represents: "The number of network interfaces (regardless of their current state) present on this system." Each interface is identified by a unique value of the ifIndex object, and the description of ifIndex constrains its value as follows: "Its value ranges between 1 and the value of ifNumber. The value for each interface must remain constant at least from one re-initialization of the entity's network management system to the next re-initialization." This constancy requirement on the value of ifIndex for a particular interface is vital for efficient management. However, an increasing number of devices allow for the dynamic addition/removal of network interfaces. One example of this is a dynamic ability to configure the use of SLIP/PPP over a character- oriented port. For such dynamic additions/removals, the combination of the constancy requirement and the restriction that the value of ifIndex is less than ifNumber is problematic. McCloghrie & Kastenholz [Page 11]
Internet Draft Interfaces Group MIB October 1999 Redefining ifNumber to be the largest value of ifIndex was rejected since it would not help. Such a re-definition would require ifNumber to be deprecated and the utility of the redefined object would be questionable. Alternatively, ifNumber could be deprecated and not replaced. However, the deprecation of ifNumber would require a change to that portion of ifIndex's definition which refers to ifNumber. So, since the definition of ifIndex must be changed anyway in order to solve the problem, changes to ifNumber do not benefit the solution. The solution adopted in this memo is just to delete the requirement that the value of ifIndex must be less than the value of ifNumber, and to retain ifNumber with its current definition. This is a minor change in the semantics of ifIndex; however, all existing agent implementations conform to this new definition, and in the interests of not requiring changes to existing agent implementations and to the many existing media-specific MIBs, this memo assumes that this change does not require ifIndex to be deprecated. Experience indicates that this assumption does "break" a few management applications, but this is considered preferable to breaking all agent implementations. This solution also results in the possibility of "holes" in the ifTable, i.e., the ifIndex values of conceptual rows in the ifTable are not necessarily contiguous, but SNMP's GetNext (and SNMPv2's GetBulk) operation easily deals with such holes. The value of ifNumber still represents the number of conceptual rows, which increases/decreases as new interfaces are dynamically added/removed. The requirement for constancy (between re-initializations) of an interface's ifIndex value is met by requiring that after an interface is dynamically removed, its ifIndex value is not re-used by a *different* dynamically added interface until after the following re-initialization of the network management system. This avoids the need for assignment (in advance) of ifIndex values for all possible interfaces that might be added dynamically. The exact meaning of a "different" interface is hard to define, and there will be gray areas. Any firm definition in this document would likely turn out to be inadequate. Instead, implementors must choose what it means in their particular situation, subject to the following rules: (1) a previously-unused value of ifIndex must be assigned to a dynamically added interface if an agent has no knowledge of McCloghrie & Kastenholz [Page 12]
Internet Draft Interfaces Group MIB October 1999 whether the interface is the "same" or "different" to a previously incarnated interface. (2) a management station, not noticing that an interface has gone away and another has come into existence, must not be confused when calculating the difference between the counter values retrieved on successive polls for a particular ifIndex value. When the new interface is the same as an old interface, but a discontinuity in the value of the interface's counters cannot be avoided, the ifTable has (until now) required that a new ifIndex value be assigned to the returning interface. That is, either all counter values have had to be retained during the absence of an interface in order to use the same ifIndex value on that interface's return, or else a new ifIndex value has had to be assigned to the returning interface. Both alternatives have proved to be burdensome to some implementations: (1) maintaining the counter values may not be possible (e.g., if they are maintained on removable hardware), (2) using a new ifIndex value presents extra work for management applications. While the potential need for such extra work is unavoidable on agent re-initializations, it is desirable to avoid it between re-initializations. To address this, a new object, ifCounterDiscontinuityTime, has been defined to record the time of the last discontinuity in an interface's counters. By monitoring the value of this new object, a management application can now detect counter discontinuities without the ifIndex value of the interface being changed. Thus, an agent which implements this new object should, when a new interface is the same as an old interface, retain that interface's ifIndex value and update if necessary the interface's value of ifCounterDiscontinuityTime. With this new object, a management application must, when calculating differences between counter values retrieved on successive polls, discard any calculated difference for which the value of ifCounterDiscontinuityTime is different for the two polls. (Note that this test must be performed in addition to the normal checking of sysUpTime to detect an agent re-initialization.) Since such discards are a waste of network management processing and bandwidth, an agent should not update the value of ifCounterDiscontinuityTime unless absolutely necessary. McCloghrie & Kastenholz [Page 13]
Internet Draft Interfaces Group MIB October 1999 While defining this new object is a change in the semantics of the ifTable counter objects, it is impractical to deprecate and redefine all these counters because of their wide deployment and importance. Also, a survey of implementations indicates that many agents and management applications do not correctly implement this aspect of the current semantics (because of the burdensome issues mentioned above), such that the practical implications of such a change is small. Thus, this breach of the SMI's rules is considered to be acceptable. Note, however, that the addition of ifCounterDiscontinuityTime does not change the fact that: it is necessary at certain times for the assignment of ifIndex values to change on a re-initialization of the agent (such as a reboot). The possibility of ifIndex value re-assignment must be accommodated by a management application whenever the value of sysUpTime is reset to zero. Note also that some agents support multiple "naming scopes", e.g., for an SNMPv1 agent, multiple values of the SNMPv1 community string. For such an agent (e.g., a CNM agent which supports a different subset of interfaces for different customers), there is no required relationship between the ifIndex values which identify interfaces in one naming scope and those which identify interfaces in another naming scope. It is the agent's choice as to whether the same or different ifIndex values identify the same or different interfaces in different naming scopes. Because of the restriction of the value of ifIndex to be less than ifNumber, interfaces have been numbered with small integer values. This has led to the ability by humans to use the ifIndex values as (somewhat) user-friendly names for network interfaces (e.g., "interface number 3"). With the relaxation of the restriction on the value of ifIndex, there is now the possibility that ifIndex values could be assigned as very large numbers (e.g., memory addresses). Such numbers would be much less user- friendly. Therefore, this memo recommends that ifIndex values still be assigned as (relatively) small integer values starting at 1, even though the values in use at any one time are not necessarily contiguous. (Note that this makes remembering which values have been assigned easy for agents which dynamically add new interfaces) A new problem is introduced by representing each sub-layer as an ifTable entry. Previously, there usually was a simple, direct, mapping of interfaces to the physical ports on systems. This mapping would be McCloghrie & Kastenholz [Page 14]
Internet Draft Interfaces Group MIB October 1999 based on the ifIndex value. However, by having an ifTable entry for each interface sub-layer, mapping from interfaces to physical ports becomes increasingly problematic. To address this issue, a new object, ifName, is added to the MIB. This object contains the device's local name (e.g., the name used at the device's local console) for the interface of which the relevant entry in the ifTable is a component. For example, consider a router having an interface composed of PPP running over an RS-232 port. If the router uses the name "wan1" for the (combined) interface, then the ifName objects for the corresponding PPP and RS-232 entries in the ifTable would both have the value "wan1". On the other hand, if the router uses the name "wan1.1" for the PPP interface and "wan1.2" for the RS-232 port, then the ifName objects for the corresponding PPP and RS-232 entries in the ifTable would have the values "wan1.1" and "wan1.2", respectively. As an another example, consider an agent which responds to SNMP queries concerning an interface on some other (proxied) device: if such a proxied device associates a particular identifier with an interface, then it is appropriate to use this identifier as the value of the interface's ifName, since the local console in this case is that of the proxied device. In contrast, the existing ifDescr object is intended to contain a description of an interface, whereas another new object, ifAlias, provides a location in which a network management application can store a non-volatile interface-naming value of its own choice. The ifAlias object allows a network manager to give one or more interfaces their own unique names, irrespective of any interface-stack relationship. Further, the ifAlias name is non-volatile, and thus an interface must retain its assigned ifAlias value across reboots, even if an agent chooses a new ifIndex value for the interface. 3.1.6. Counter Size As the speed of network media increase, the minimum time in which a 32 bit counter will wrap decreases. For example, a 10Mbs stream of back- to-back, full-size packets causes ifInOctets to wrap in just over 57 minutes; at 100Mbs, the minimum wrap time is 5.7 minutes, and at 1Gbs, the minimum is 34 seconds. Requiring that interfaces be polled frequently enough not to miss a counter wrap is increasingly problematic. A rejected solution to this problem was to scale the counters; for example, ifInOctets could be changed to count received octets in, say, 1024 byte blocks. While it would provide acceptable functionality at McCloghrie & Kastenholz [Page 15]
Internet Draft Interfaces Group MIB October 1999 high rates of the counted-events, at low rates it suffers. If there is little traffic on an interface, there might be a significant interval before enough of the counted-events occur to cause the scaled counter to be incremented. Traffic would then appear to be very bursty, leading to incorrect conclusions of the network's performance. Instead, this memo adopts expanded, 64 bit, counters. These counters are provided in new "high capacity" groups. The old, 32-bit, counters have not been deprecated. The 64-bit counters are to be used only when the 32-bit counters do not provide enough capacity; that is, when the 32 bit counters could wrap too fast. For interfaces that operate at 20,000,000 (20 million) bits per second or less, 32-bit byte and packet counters MUST be used. For interfaces that operate faster than 20,000,000 bits/second, and slower than 650,000,000 bits/second, 32-bit packet counters MUST be used and 64-bit octet counters MUST be used. For interfaces that operate at 650,000,000 bits/second or faster, 64-bit packet counters AND 64-bit octet counters MUST be used. These speed thresholds were chosen as reasonable compromises based on the following: (1) The cost of maintaining 64-bit counters is relatively high, so minimizing the number of agents which must support them is desirable. Common interfaces (such as 10Mbs Ethernet) should not require them. (2) 64-bit counters are a new feature, introduced in SNMPv2. It is reasonable to expect that support for them will be spotty for the immediate future. Thus, we wish to limit them to as few systems as possible. This, in effect, means that 64-bit counters should be limited to higher speed interfaces. Ethernet (10,000,000 bps) and Token Ring (16,000,000 bps) are fairly wide-spread so it seems reasonable to not require 64-bit counters for these interfaces. (3) The 32-bit octet counters will wrap in the following times, for the following interfaces (when transmitting maximum-sized packets back-to-back): - 10Mbs Ethernet: 57 minutes, - 16Mbs Token Ring: 36 minutes, McCloghrie & Kastenholz [Page 16]
Internet Draft Interfaces Group MIB October 1999 - a US T3 line (45 megabits): 12 minutes, - FDDI: 5.7 minutes (4) The 32-bit packet counters wrap in about 57 minutes when 64-byte packets are transmitted back-to-back on a 650,000,000 bit/second link. As an aside, a 1-terabit/second (1,000 Gbs) link will cause a 64 bit octet counter to wrap in just under 5 years. Conversely, an 81,000,000 terabit/second link is required to cause a 64-bit counter to wrap in 30 minutes. We believe that, while technology rapidly marches forward, this link speed will not be achieved for at least several years, leaving sufficient time to evaluate the introduction of 96 bit counters. When 64-bit counters are in use, the 32-bit counters MUST still be available. They will report the low 32-bits of the associated 64-bit count (e.g., ifInOctets will report the least significant 32 bits of ifHCInOctets). This enhances inter-operability with existing implementations at a very minimal cost to agents. The new "high capacity" groups are: (1) the ifHCFixedLengthGroup for character-oriented/fixed-length interfaces, and the ifHCPacketGroup for packet-based interfaces; both of these groups include 64 bit counters for octets, and (2) the ifVHCPacketGroup for packet-based interfaces; this group includes 64 bit counters for octets and packets. 3.1.7. Interface Speed Network speeds are increasing. The range of ifSpeed is limited to reporting a maximum speed of (2**31)-1 bits/second, or approximately 2.2Gbs. SONET defines an OC-48 interface, which is defined at operating at 48 times 51 Mbs, which is a speed in excess of 2.4Gbs. Thus, ifSpeed is insufficient for the future, and this memo defines an additional object: ifHighSpeed. The ifHighSpeed object reports the speed of the interface in 1,000,000 (1 million) bits/second units. Thus, the true speed of the interface will be the value reported by this object, plus or minus 500,000 bits/second. McCloghrie & Kastenholz [Page 17]
Internet Draft Interfaces Group MIB October 1999 Other alternatives considered (but rejected) were: (1) Making the interface speed a 64-bit gauge. This was rejected since the current SMI does not allow such a syntax. Furthermore, even if 64-bit gauges were available, their use would require additional complexity in agents due to an increased requirement for 64-bit operations. (2) We also considered making "high-32 bit" and "low-32-bit" objects which, when combined, would be a 64-bit value. This simply seemed overly complex for what we are trying to do. Furthermore, a full 64-bits of precision does not seem necessary. The value of ifHighSpeed will be the only report of interface speed for interfaces that are faster than 4,294,967,295 bits per second. At this speed, the granularity of ifHighSpeed will be 1,000,000 bits per second, thus the error will be 1/4294, or about 0.02%. This seems reasonable. (3) Adding a "scale" object, which would define the units which ifSpeed's value is. This would require two additional objects; one for the scaling object, and one to replace the current ifSpeed. This later object is required since the semantics of ifSpeed would be significantly altered, and manager stations which do not understand the new semantics would be confused. 3.1.8. Multicast/Broadcast Counters In MIB-II, the ifTable counters for multicast and broadcast packets are combined as counters of non-unicast packets. In contrast, the ifExtensions MIB [19] defined one set of counters for multicast, and a separate set for broadcast packets. With the separate counters, the original combined counters become redundant. To avoid this redundancy, the non-unicast counters are deprecated. For the output broadcast and multicast counters defined in RFC 1229, their definitions varied slightly from the packet counters in the ifTable, in that they did not count errors/discarded packets. Thus, this memo defines new objects with better aligned definitions. Counters with 64 bits of range are also needed, as explained above. McCloghrie & Kastenholz [Page 18]
Internet Draft Interfaces Group MIB October 1999 3.1.9. Trap Enable In the multi-layer interface model, each sub-layer for which there is an entry in the ifTable can generate linkUp/linkDown Traps. Since interface state changes would tend to propagate through the interface (from top to bottom, or bottom to top), it is likely that several traps would be generated for each linkUp/linkDown occurrence. It is desirable to provide a mechanism for manager stations to control the generation of these traps. To this end, the ifLinkUpDownTrapEnable object has been added. This object allows managers to limit generation of traps to just the sub-layers of interest. The default setting should limit the number of traps generated to one per interface per linkUp/linkDown event. Furthermore, it seems that the state changes of most interest to network managers occur at the lowest level of an interface stack. Therefore we specify that by default, only the lowest sub-layer of the interface generate traps. 3.1.10. Addition of New ifType values Over time, there is the need to add new ifType enumerated values for new interface types. If the syntax of ifType were defined in the MIB in section 6, then a new version of this MIB would have to be re-issued in order to define new values. In the past, re-issuing of a MIB has occurred only after several years. Therefore, the syntax of ifType is changed to be a textual convention, such that the enumerated integer values are now defined in the textual convention, IANAifType, defined in a different document. This allows additional values to be documented without having to re-issue a new version of this document. The Internet Assigned Number Authority (IANA) is responsible for the assignment of all Internet numbers, including various SNMP-related numbers, and specifically, new ifType values. 3.1.11. InterfaceIndex Textual Convention A new textual convention, InterfaceIndex, has been defined. This textual convention "contains" all of the semantics of the ifIndex object. This allows other MIB modules to easily import the semantics of ifIndex. McCloghrie & Kastenholz [Page 19]
Internet Draft Interfaces Group MIB October 1999 3.1.12. New states for IfOperStatus Three new states have been added to ifOperStatus: 'dormant', 'notPresent', and 'lowerLayerDown'. The dormant state indicates that the relevant interface is not actually in a condition to pass packets (i.e., it is not 'up') but is in a "pending" state, waiting for some external event. For "on-demand" interfaces, this new state identifies the situation where the interface is waiting for events to place it in the up state. Examples of such events might be: (1) having packets to transmit before establishing a connection to a remote system; (2) having a remote system establish a connection to the interface (e.g. dialing up to a slip-server). The notPresent state is a refinement on the down state which indicates that the relevant interface is down specifically because some component (typically, a hardware component) is not present in the managed system. Examples of use of the notPresent state are: (1) to allow an interface's conceptual row including its counter values to be retained across a "hot swap" of a card/module, and/or (2) to allow an interface's conceptual row to be created, and thereby enable interfaces to be pre-configured prior to installation of the hardware needed to make the interface operational. Agents are not required to support interfaces in the notPresent state. However, from a conceptual viewpoint, when a row in the ifTable is created, it first enters the notPresent state and then subsequently transitions into the down state; similarly, when a row in the ifTable is deleted, it first enters the notPresent state and then subsequently the object instances are deleted. For an agent with no support for notPresent, both of these transitions (from the notPresent state to the down state, and from the notPresent state to the instances being removed) are immediate, i.e., the transition does not last long enough to be recorded by ifOperStatus. Even for those agents which do support interfaces in the notPresent state, the length of time and conditions under which an interface stays in the notPresent state is implementation-specific. McCloghrie & Kastenholz [Page 20]
Internet Draft Interfaces Group MIB October 1999 The lowerLayerDown state is also a refinement on the down state. This new state indicates that this interface runs "on top of" one or more other interfaces (see ifStackTable) and that this interface is down specifically because one or more of these lower-layer interfaces are down. 3.1.13. IfAdminStatus and IfOperStatus The down state of ifOperStatus now has two meanings, depending on the value of ifAdminStatus. (1) if ifAdminStatus is not down and ifOperStatus is down then a fault condition is presumed to exist on the interface. (2) if ifAdminStatus is down, then ifOperStatus will normally also be down (or notPresent) i.e., there is not (necessarily) a fault condition on the interface. Note that when ifAdminStatus transitions to down, ifOperStatus will normally also transition to down. In this situation, it is possible that ifOperStatus's transition will not occur immediately, but rather after a small time lag to complete certain operations before going "down"; for example, it might need to finish transmitting a packet. If a manager station finds that ifAdminStatus is down and ifOperStatus is not down for a particular interface, the manager station should wait a short while and check again. If the condition still exists, only then should it raise an error indication. Naturally, it should also ensure that ifLastChange has not changed during this interval. Whenever an interface table entry is created (usually as a result of system initialization), the relevant instance of ifAdminStatus is set to down, and ifOperStatus will be down or notPresent. An interface may be enabled in two ways: either as a result of explicit management action (e.g. setting ifAdminStatus to up) or as a result of the managed system's initialization process. When ifAdminStatus changes to the up state, the related ifOperStatus should do one of the following: (1) Change to the up state if and only if the interface is able to send and receive packets. (2) Change to the lowerLayerDown state if and only if the interface is prevented from entering the up state because of the state of one or more of the interfaces beneath it in the interface stack. McCloghrie & Kastenholz [Page 21]
Internet Draft Interfaces Group MIB October 1999 (3) Change to the dormant state if and only if the interface is found to be operable, but the interface is waiting for other, external, events to occur before it can transmit or receive packets. Presumably when the expected events occur, the interface will then change to the up state. (4) Remain in the down state if an error or other fault condition is detected on the interface. (5) Change to the unknown state if, for some reason, the state of the interface can not be ascertained. (6) Change to the testing state if some test(s) must be performed on the interface. Presumably after completion of the test, the interface's state will change to up, dormant, or down, as appropriate. (7) Remain in the notPresent state if interface components are missing. 3.1.14. IfOperStatus in an Interface Stack When an interface is a part of an interface-stack, but is not the lowest interface in the stack, then: (1) ifOperStatus has the value 'up' if it is able to pass packets due to one or more interfaces below it in the stack being 'up', irrespective of whether other interfaces below it are 'down', 'dormant', 'notPresent', 'lowerLayerDown', 'unknown' or 'testing'. (2) ifOperStatus may have the value 'up' or 'dormant' if one or more interfaces below it in the stack are 'dormant', and all others below it are either 'down', 'dormant', 'notPresent', 'lowerLayerDown', 'unknown' or 'testing'. (3) ifOperStatus has the value 'lowerLayerDown' while all interfaces below it in the stack are either 'down', 'notPresent', 'lowerLayerDown', or 'testing'. 3.1.15. Traps The exact definition of when linkUp and linkDown traps are generated has been changed to reflect the changes to ifAdminStatus and ifOperStatus. McCloghrie & Kastenholz [Page 22]
Internet Draft Interfaces Group MIB October 1999 Operational experience indicates that management stations are most concerned with an interface being in the down state and the fact that this state may indicate a failure. Thus, it is most useful to instrument transitions into/out of either the up state or the down state. Instrumenting transitions into or out of the up state was rejected since it would have the drawback that a demand interface might have many transitions between up and dormant, leading to many linkUp traps and no linkDown traps. Furthermore, if a node's only interface is the demand interface, then a transition to dormant would entail generation of a linkDown trap, necessitating bringing the link to the up state (and a linkUp trap)!! On the other hand, instrumenting transitions into or out of the down state (to/from all other states except notPresent) has the advantages: (1) A transition into the down state (from a state other than notPresent) will occur when an error is detected on an interface. Error conditions are presumably of great interest to network managers. (2) Departing the down state (to a state other than the notPresent state) generally indicates that the interface is going to either up or dormant, both of which are considered "healthy" states. Furthermore, it is believed that generating traps on transitions into or out of the down state (except to/from the notPresent state) is generally consistent with current usage and interpretation of these traps by manager stations. Transitions to/from the notPresent state are concerned with the insertion and removal of hardware, and are outside the scope of these traps. Therefore, this memo defines that LinkUp and linkDown traps are generated just after ifOperStatus leaves, or just before it enters, the down state, respectively; except that LinkUp and linkDown traps are never generated on transitions to/from the notPresent state. Note that this definition allows a node with only one interface to transmit a linkDown trap before that interface goes down. (Of course, when the interface is going down because of a failure condition, the linkDown trap probably cannot be successfully transmitted anyway.) McCloghrie & Kastenholz [Page 23]
Internet Draft Interfaces Group MIB October 1999 Some interfaces perform a link "training" function when trying to bring the interface up. In the event that such an interface were defective, then the training function would fail and the interface would remain down, and the training function might be repeated at appropriate intervals. If the interface, while performing this training function, were considered to the in the testing state, then linkUp and linkDown traps would be generated for each start and end of the training function. This is not the intent of the linkUp and linkDown traps, and therefore, while performing such a training function, the interface's state should be represented as down. An exception to the above generation of linkUp/linkDown traps on changes in ifOperStatus, occurs when an interface is "flapping", i.e., when it is rapidly oscillating between the up and down states. If traps were generated for each such oscillation, the network and the network management system would be flooded with unnecessary traps. In such a situation, the agent should limit the rate at which it generates traps. 3.1.16. ifSpecific The original definition of the OBJECT IDENTIFIER value of ifSpecific was not sufficiently clear. As a result, different implementors used it differently, and confusion resulted. Some implementations set the value of ifSpecific to the OBJECT IDENTIFIER that defines the media-specific MIB, i.e., the "foo" of: foo OBJECT IDENTIFIER ::= { transmission xxx } while others set it to be OBJECT IDENTIFIER of the specific table or entry in the appropriate media-specific MIB (i.e., fooTable or fooEntry), while still others set it be the OBJECT IDENTIFIER of the index object of the table's row, including instance identifier, (i.e., fooIfIndex.ifIndex). A definition based on the latter would not be sufficient unless it also allowed for media-specific MIBs which include several tables, where each table has its own (different) indexing. The only definition that can both be made explicit and can cover all the useful situations is to have ifSpecific be the most general value for the media-specific MIB module (the first example given above). This effectively makes it redundant because it contains no more information than is provided by ifType. Thus, ifSpecific has been deprecated. 3.1.17. Creation/Deletion of Interfaces While some interfaces, for example, most physical interfaces, cannot be created via network management, other interfaces such as logical McCloghrie & Kastenholz [Page 24]
Internet Draft Interfaces Group MIB October 1999 interfaces sometimes can be. The ifTable contains only generic information about an interface. Almost all 'create-able' interfaces have other, media-specific, information through which configuration parameters may be supplied prior to creating such an interface. Thus, the ifTable does not itself support the creation or deletion of an interface (specifically, it has no RowStatus [6] column). Rather, if a particular interface type supports the dynamic creation and/or deletion of an interface of that type, then that media-specific MIB should include an appropriate RowStatus object (see the ATM LAN-Emulation Client MIB [20] for an example of a MIB which does this). Typically, when such a RowStatus object is created/deleted, then the conceptual row in the ifTable appears/disappears as a by-product, and an ifIndex value (chosen by the agent) is stored in an appropriate object in the media- specific MIB. 3.1.18. All Values Must be Known There are a number of situations where an agent does not know the value of one or more objects for a particular interface. In all such circumstances, an agent MUST NOT instantiate an object with an incorrect value; rather, it MUST respond with the appropriate error/exception condition (e.g., noSuchInstance for SNMPv2). One example is where an agent is unable to count the occurrences defined by one (or more) of the ifTable counters. In this circumstance, the agent MUST NOT instantiate the particular counter with a value of, say, zero. To do so would be to provide mis-information to a network management application reading the zero value, and thereby assuming that there have been no occurrences of the event (e.g., no input errors because ifInErrors is always zero). Sometimes the lack of knowledge of an object's value is temporary. For example, when the MTU of an interface is a configured value and a device dynamically learns the configured value through (after) exchanging messages over the interface (e.g., ATM LAN-Emulation [20]). In such a case, the value is not known until after the ifTable entry has already been created. In such a case, the ifTable entry should be created without an instance of the object whose value is unknown; later, when the value becomes known, the missing object can then be instantiated (e.g., the instance of ifMtu is only instantiated once the interface's MTU becomes known). As a result of this "known values" rule, management applications MUST be able to cope with the responses to retrieving the object instances within a conceptual row of the ifTable revealing that some of the row's McCloghrie & Kastenholz [Page 25]
Internet Draft Interfaces Group MIB October 1999 columnar objects are missing/not available. McCloghrie & Kastenholz [Page 26]
Internet Draft Interfaces Group MIB October 1999 4. Media-Specific MIB Applicability The exact use and semantics of many objects in this MIB are open to some interpretation. This is a result of the generic nature of this MIB. It is not always possible to come up with specific, unambiguous, text that covers all cases and yet preserves the generic nature of the MIB. Therefore, it is incumbent upon a media-specific MIB designer to, wherever necessary, clarify the use of the objects in this MIB with respect to the media-specific MIB. Specific areas of clarification include Layering Model The media-specific MIB designer MUST completely and unambiguously specify the layering model used. Each individual sub-layer must be identified, as must the ifStackTable's portrayal of the relationship(s) between the sub-layers. Virtual Circuits The media-specific MIB designer MUST specify whether virtual circuits are assigned entries in the ifTable or not. If they are, compelling rationale must be presented. ifRcvAddressTable The media-specific MIB designer MUST specify the applicability of the ifRcvAddressTable. ifType For each of the ifType values to which the media-specific MIB applies, it must specify the mapping of ifType values to media- specific MIB module(s) and instances of MIB objects within those modules. ifXxxOctets The definitions of ifInOctets and ifOutOctets (and similarly, ifHCInOctets and ifHCOutOctets) specify that their values include framing characters. The media-specific MIB designer MUST specify any special conditions of the media concerning the inclusion of framing characters, especially with respect to frames with errors. However, wherever this interface MIB is specific in the semantics, DESCRIPTION, or applicability of objects, the media-specific MIB designer MUST NOT change said semantics, DESCRIPTION, or applicability. McCloghrie & Kastenholz [Page 27]
Internet Draft Interfaces Group MIB October 1999 5. Overview This MIB consists of 4 tables: ifTable This table is the ifTable from MIB-II. ifXTable This table contains objects that have been added to the Interface MIB as a result of the Interface Evolution effort, or replacements for objects of the original (MIB-II) ifTable that were deprecated because the semantics of said objects have significantly changed. This table also contains objects that were previously in the ifExtnsTable. ifStackTable This table contains objects that define the relationships among the sub-layers of an interface. ifRcvAddressTable This table contains objects that are used to define the media-level addresses which this interface will receive. This table is a generic table. The designers of media-specific MIBs must define exactly how this table applies to their specific MIB. McCloghrie & Kastenholz [Page 28]
Internet Draft Interfaces Group MIB October 1999 6. Interfaces Group Definitions IF-MIB DEFINITIONS ::= BEGIN IMPORTS MODULE-IDENTITY, OBJECT-TYPE, Counter32, Gauge32, Counter64, Integer32, TimeTicks, mib-2, NOTIFICATION-TYPE FROM SNMPv2-SMI TEXTUAL-CONVENTION, DisplayString, PhysAddress, TruthValue, RowStatus, TimeStamp, AutonomousType, TestAndIncr FROM SNMPv2-TC MODULE-COMPLIANCE, OBJECT-GROUP, NOTIFICATION-GROUP FROM SNMPv2-CONF snmpTraps FROM SNMPv2-MIB IANAifType FROM IANAifType-MIB; ifMIB MODULE-IDENTITY LAST-UPDATED "9910110000Z" ORGANIZATION "IETF Interfaces MIB Working Group" CONTACT-INFO " Keith McCloghrie Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 US 408-526-5260 kzm@cisco.com" DESCRIPTION "The MIB module to describe generic objects for network interface sub-layers. This MIB is an updated version of MIB-II's ifTable, and incorporates the extensions defined in RFC 1229." REVISION "9910110000Z" DESCRIPTION -- xxxx to be filled in by RFC-EDITOR "Clarifications agreed upon by the Interfaces MIB WG, and published as RFC xxxx." REVISION "9602282155Z" DESCRIPTION "Revisions made by the Interfaces MIB WG, and published in RFC 2233." REVISION "9311082155Z" DESCRIPTION "Initial revision, published as part of RFC 1573." McCloghrie & Kastenholz [Page 29]
Internet Draft Interfaces Group MIB October 1999 ::= { mib-2 31 } ifMIBObjects OBJECT IDENTIFIER ::= { ifMIB 1 } interfaces OBJECT IDENTIFIER ::= { mib-2 2 } -- -- Textual Conventions -- -- OwnerString has the same semantics as used in RFC 1271 OwnerString ::= TEXTUAL-CONVENTION DISPLAY-HINT "255a" STATUS deprecated DESCRIPTION "This data type is used to model an administratively assigned name of the owner of a resource. This information is taken from the NVT ASCII character set. It is suggested that this name contain one or more of the following: ASCII form of the manager station's transport address, management station name (e.g., domain name), network management personnel's name, location, or phone number. In some cases the agent itself will be the owner of an entry. In these cases, this string shall be set to a string starting with 'agent'." SYNTAX OCTET STRING (SIZE(0..255)) -- InterfaceIndex contains the semantics of ifIndex and should be used -- for any objects defined in other MIB modules that need these semantics. InterfaceIndex ::= TEXTUAL-CONVENTION DISPLAY-HINT "d" STATUS current DESCRIPTION "A unique value, greater than zero, for each interface or interface sub-layer in the managed system. It is recommended that values are assigned contiguously starting from 1. The value for each interface sub-layer must remain constant at least from one re-initialization of the entity's network management system to the next re-initialization." SYNTAX Integer32 (1..2147483647) McCloghrie & Kastenholz [Page 30]
Internet Draft Interfaces Group MIB October 1999 InterfaceIndexOrZero ::= TEXTUAL-CONVENTION DISPLAY-HINT "d" STATUS current DESCRIPTION "This textual convention is an extension of the InterfaceIndex convention. The latter defines a greater than zero value used to identify an interface or interface sub-layer in the managed system. This extension permits the additional value of zero. the value zero is object-specific and must therefore be defined as part of the description of any object which uses this syntax. Examples of the usage of zero might include situations where interface was unknown, or when none or all interfaces need to be referenced." SYNTAX Integer32 (0..2147483647) McCloghrie & Kastenholz [Page 31]
Internet Draft Interfaces Group MIB October 1999 ifNumber OBJECT-TYPE SYNTAX Integer32 MAX-ACCESS read-only STATUS current DESCRIPTION "The number of network interfaces (regardless of their current state) present on this system." ::= { interfaces 1 } ifTableLastChange OBJECT-TYPE SYNTAX TimeTicks MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime at the time of the last creation or deletion of an entry in the ifTable. If the number of entries has been unchanged since the last re-initialization of the local network management subsystem, then this object contains a zero value." ::= { ifMIBObjects 5 } -- the Interfaces table -- The Interfaces table contains information on the entity's -- interfaces. Each sub-layer below the internetwork-layer -- of a network interface is considered to be an interface. ifTable OBJECT-TYPE SYNTAX SEQUENCE OF IfEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A list of interface entries. The number of entries is given by the value of ifNumber." ::= { interfaces 2 } ifEntry OBJECT-TYPE SYNTAX IfEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "An entry containing management information applicable to a particular interface." INDEX { ifIndex } McCloghrie & Kastenholz [Page 32]
Internet Draft Interfaces Group MIB October 1999 ::= { ifTable 1 } IfEntry ::= SEQUENCE { ifIndex InterfaceIndex, ifDescr DisplayString, ifType IANAifType, ifMtu Integer32, ifSpeed Gauge32, ifPhysAddress PhysAddress, ifAdminStatus INTEGER, ifOperStatus INTEGER, ifLastChange TimeTicks, ifInOctets Counter32, ifInUcastPkts Counter32, ifInNUcastPkts Counter32, -- deprecated ifInDiscards Counter32, ifInErrors Counter32, ifInUnknownProtos Counter32, ifOutOctets Counter32, ifOutUcastPkts Counter32, ifOutNUcastPkts Counter32, -- deprecated ifOutDiscards Counter32, ifOutErrors Counter32, ifOutQLen Gauge32, -- deprecated ifSpecific OBJECT IDENTIFIER -- deprecated } ifIndex OBJECT-TYPE SYNTAX InterfaceIndex MAX-ACCESS read-only STATUS current DESCRIPTION "A unique value, greater than zero, for each interface. It is recommended that values are assigned contiguously starting from 1. The value for each interface sub-layer must remain constant at least from one re-initialization of the entity's network management system to the next re- initialization." ::= { ifEntry 1 } ifDescr OBJECT-TYPE SYNTAX DisplayString (SIZE (0..255)) MAX-ACCESS read-only McCloghrie & Kastenholz [Page 33]
Internet Draft Interfaces Group MIB October 1999 STATUS current DESCRIPTION "A textual string containing information about the interface. This string should include the name of the manufacturer, the product name and the version of the interface hardware/software." ::= { ifEntry 2 } ifType OBJECT-TYPE SYNTAX IANAifType MAX-ACCESS read-only STATUS current DESCRIPTION "The type of interface. Additional values for ifType are assigned by the Internet Assigned Numbers Authority (IANA), through updating the syntax of the IANAifType textual convention." ::= { ifEntry 3 } ifMtu OBJECT-TYPE SYNTAX Integer32 MAX-ACCESS read-only STATUS current DESCRIPTION "The size of the largest packet which can be sent/received on the interface, specified in octets. For interfaces that are used for transmitting network datagrams, this is the size of the largest network datagram that can be sent on the interface." ::= { ifEntry 4 } ifSpeed OBJECT-TYPE SYNTAX Gauge32 MAX-ACCESS read-only STATUS current DESCRIPTION "An estimate of the interface's current bandwidth in bits per second. For interfaces which do not vary in bandwidth or for those where no accurate estimation can be made, this object should contain the nominal bandwidth. If the bandwidth of the interface is greater than the maximum value reportable by this object then this object should report its maximum value (4,294,967,295) and ifHighSpeed must be used to report the interace's speed. For a sub-layer which has no concept of bandwidth, this object should be zero." McCloghrie & Kastenholz [Page 34]
Internet Draft Interfaces Group MIB October 1999 ::= { ifEntry 5 } ifPhysAddress OBJECT-TYPE SYNTAX PhysAddress MAX-ACCESS read-only STATUS current DESCRIPTION "The interface's address at its protocol sub-layer. For example, for an 802.x interface, this object normally contains a MAC address. The interface's media-specific MIB must define the bit and byte ordering and the format of the value of this object. For interfaces which do not have such an address (e.g., a serial line), this object should contain an octet string of zero length." ::= { ifEntry 6 } ifAdminStatus OBJECT-TYPE SYNTAX INTEGER { up(1), -- ready to pass packets down(2), testing(3) -- in some test mode } MAX-ACCESS read-write STATUS current DESCRIPTION "The desired state of the interface. The testing(3) state indicates that no operational packets can be passed. When a managed system initializes, all interfaces start with ifAdminStatus in the down(2) state. As a result of either explicit management action or per configuration information retained by the managed system, ifAdminStatus is then changed to either the up(1) or testing(3) states (or remains in the down(2) state)." ::= { ifEntry 7 } ifOperStatus OBJECT-TYPE SYNTAX INTEGER { up(1), -- ready to pass packets down(2), testing(3), -- in some test mode unknown(4), -- status can not be determined -- for some reason. dormant(5), notPresent(6), -- some component is missing lowerLayerDown(7) -- down due to state of McCloghrie & Kastenholz [Page 35]
Internet Draft Interfaces Group MIB October 1999 -- lower-layer interface(s) } MAX-ACCESS read-only STATUS current DESCRIPTION "The current operational state of the interface. The testing(3) state indicates that no operational packets can be passed. If ifAdminStatus is down(2) then ifOperStatus should be down(2). If ifAdminStatus is changed to up(1) then ifOperStatus should change to up(1) if the interface is ready to transmit and receive network traffic; it should change to dormant(5) if the interface is waiting for external actions (such as a serial line waiting for an incoming connection); it should remain in the down(2) state if and only if there is a fault that prevents it from going to the up(1) state; it should remain in the notPresent(6) state if the interface has missing (typically, hardware) components." ::= { ifEntry 8 } ifLastChange OBJECT-TYPE SYNTAX TimeTicks MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime at the time the interface entered its current operational state. If the current state was entered prior to the last re-initialization of the local network management subsystem, then this object contains a zero value." ::= { ifEntry 9 } ifInOctets OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of octets received on the interface, including framing characters. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifEntry 10 } McCloghrie & Kastenholz [Page 36]
Internet Draft Interfaces Group MIB October 1999 ifInUcastPkts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The number of packets, delivered by this sub-layer to a higher (sub-)layer, which were not addressed to a multicast or broadcast address at this sub-layer. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifEntry 11 } ifInNUcastPkts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS deprecated DESCRIPTION "The number of packets, delivered by this sub-layer to a higher (sub-)layer, which were addressed to a multicast or broadcast address at this sub-layer. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime. This object is deprecated in favour of ifInMulticastPkts and ifInBroadcastPkts." ::= { ifEntry 12 } ifInDiscards OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The number of inbound packets which were chosen to be discarded even though no errors had been detected to prevent their being deliverable to a higher-layer protocol. One possible reason for discarding such a packet could be to free up buffer space. Discontinuities in the value of this counter can occur at McCloghrie & Kastenholz [Page 37]
Internet Draft Interfaces Group MIB October 1999 re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifEntry 13 } ifInErrors OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "For packet-oriented interfaces, the number of inbound packets that contained errors preventing them from being deliverable to a higher-layer protocol. For character- oriented or fixed-length interfaces, the number of inbound transmission units that contained errors preventing them from being deliverable to a higher-layer protocol. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifEntry 14 } ifInUnknownProtos OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "For packet-oriented interfaces, the number of packets received via the interface which were discarded because of an unknown or unsupported protocol. For character-oriented or fixed-length interfaces that support protocol multiplexing the number of transmission units received via the interface which were discarded because of an unknown or unsupported protocol. For any interface that does not support protocol multiplexing, this counter will always be 0. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifEntry 15 } ifOutOctets OBJECT-TYPE McCloghrie & Kastenholz [Page 38]
Internet Draft Interfaces Group MIB October 1999 SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of octets transmitted out of the interface, including framing characters. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifEntry 16 } ifOutUcastPkts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of packets that higher-level protocols requested be transmitted, and which were not addressed to a multicast or broadcast address at this sub-layer, including those that were discarded or not sent. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifEntry 17 } ifOutNUcastPkts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS deprecated DESCRIPTION "The total number of packets that higher-level protocols requested be transmitted, and which were addressed to a multicast or broadcast address at this sub-layer, including those that were discarded or not sent. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime. This object is deprecated in favour of ifOutMulticastPkts McCloghrie & Kastenholz [Page 39]
Internet Draft Interfaces Group MIB October 1999 and ifOutBroadcastPkts." ::= { ifEntry 18 } ifOutDiscards OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The number of outbound packets which were chosen to be discarded even though no errors had been detected to prevent their being transmitted. One possible reason for discarding such a packet could be to free up buffer space. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifEntry 19 } ifOutErrors OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "For packet-oriented interfaces, the number of outbound packets that could not be transmitted because of errors. For character-oriented or fixed-length interfaces, the number of outbound transmission units that could not be transmitted because of errors. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifEntry 20 } ifOutQLen OBJECT-TYPE SYNTAX Gauge32 MAX-ACCESS read-only STATUS deprecated DESCRIPTION "The length of the output packet queue (in packets)." ::= { ifEntry 21 } ifSpecific OBJECT-TYPE McCloghrie & Kastenholz [Page 40]
Internet Draft Interfaces Group MIB October 1999 SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-only STATUS deprecated DESCRIPTION "A reference to MIB definitions specific to the particular media being used to realize the interface. It is recommended that this value point to an instance of a MIB object in the media-specific MIB, i.e., that this object have the semantics associated with the InstancePointer textual convention defined in RFC 2579. In fact, it is recommended that the media-specific MIB specify what value ifSpecific should/can take for values of ifType. If no MIB definitions specific to the particular media are available, the value should be set to the OBJECT IDENTIFIER { 0 0 }." ::= { ifEntry 22 } -- -- Extension to the interface table -- -- This table replaces the ifExtnsTable table. -- ifXTable OBJECT-TYPE SYNTAX SEQUENCE OF IfXEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A list of interface entries. The number of entries is given by the value of ifNumber. This table contains additional objects for the interface table." ::= { ifMIBObjects 1 } ifXEntry OBJECT-TYPE SYNTAX IfXEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "An entry containing additional management information applicable to a particular interface." AUGMENTS { ifEntry } ::= { ifXTable 1 } IfXEntry ::= McCloghrie & Kastenholz [Page 41]
Internet Draft Interfaces Group MIB October 1999 SEQUENCE { ifName DisplayString, ifInMulticastPkts Counter32, ifInBroadcastPkts Counter32, ifOutMulticastPkts Counter32, ifOutBroadcastPkts Counter32, ifHCInOctets Counter64, ifHCInUcastPkts Counter64, ifHCInMulticastPkts Counter64, ifHCInBroadcastPkts Counter64, ifHCOutOctets Counter64, ifHCOutUcastPkts Counter64, ifHCOutMulticastPkts Counter64, ifHCOutBroadcastPkts Counter64, ifLinkUpDownTrapEnable INTEGER, ifHighSpeed Gauge32, ifPromiscuousMode TruthValue, ifConnectorPresent TruthValue, ifAlias DisplayString, ifCounterDiscontinuityTime TimeStamp } ifName OBJECT-TYPE SYNTAX DisplayString MAX-ACCESS read-only STATUS current DESCRIPTION "The textual name of the interface. The value of this object should be the name of the interface as assigned by the local device and should be suitable for use in commands entered at the device's `console'. This might be a text name, such as `le0' or a simple port number, such as `1', depending on the interface naming syntax of the device. If several entries in the ifTable together represent a single interface as named by the device, then each will have the same value of ifName. Note that for an agent which responds to SNMP queries concerning an interface on some other (proxied) device, then the value of ifName for such an interface is the proxied device's local name for it. If there is no local name, or this object is otherwise not applicable, then this object contains a zero-length string." ::= { ifXEntry 1 } McCloghrie & Kastenholz [Page 42]
Internet Draft Interfaces Group MIB October 1999 ifInMulticastPkts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The number of packets, delivered by this sub-layer to a higher (sub-)layer, which were addressed to a multicast address at this sub-layer. For a MAC layer protocol, this includes both Group and Functional addresses. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 2 } ifInBroadcastPkts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The number of packets, delivered by this sub-layer to a higher (sub-)layer, which were addressed to a broadcast address at this sub-layer. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 3 } ifOutMulticastPkts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of packets that higher-level protocols requested be transmitted, and which were addressed to a multicast address at this sub-layer, including those that were discarded or not sent. For a MAC layer protocol, this includes both Group and Functional addresses. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of McCloghrie & Kastenholz [Page 43]
Internet Draft Interfaces Group MIB October 1999 ifCounterDiscontinuityTime." ::= { ifXEntry 4 } ifOutBroadcastPkts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of packets that higher-level protocols requested be transmitted, and which were addressed to a broadcast address at this sub-layer, including those that were discarded or not sent. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 5 } -- -- High Capacity Counter objects. These objects are all -- 64 bit versions of the "basic" ifTable counters. These -- objects all have the same basic semantics as their 32-bit -- counterparts, however, their syntax has been extended -- to 64 bits. -- ifHCInOctets OBJECT-TYPE SYNTAX Counter64 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of octets received on the interface, including framing characters. This object is a 64-bit version of ifInOctets. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 6 } ifHCInUcastPkts OBJECT-TYPE SYNTAX Counter64 MAX-ACCESS read-only McCloghrie & Kastenholz [Page 44]
Internet Draft Interfaces Group MIB October 1999 STATUS current DESCRIPTION "The number of packets, delivered by this sub-layer to a higher (sub-)layer, which were not addressed to a multicast or broadcast address at this sub-layer. This object is a 64-bit version of ifInUcastPkts. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 7 } ifHCInMulticastPkts OBJECT-TYPE SYNTAX Counter64 MAX-ACCESS read-only STATUS current DESCRIPTION "The number of packets, delivered by this sub-layer to a higher (sub-)layer, which were addressed to a multicast address at this sub-layer. For a MAC layer protocol, this includes both Group and Functional addresses. This object is a 64-bit version of ifInMulticastPkts. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 8 } ifHCInBroadcastPkts OBJECT-TYPE SYNTAX Counter64 MAX-ACCESS read-only STATUS current DESCRIPTION "The number of packets, delivered by this sub-layer to a higher (sub-)layer, which were addressed to a broadcast address at this sub-layer. This object is a 64-bit version of ifInBroadcastPkts. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 9 } McCloghrie & Kastenholz [Page 45]
Internet Draft Interfaces Group MIB October 1999 ifHCOutOctets OBJECT-TYPE SYNTAX Counter64 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of octets transmitted out of the interface, including framing characters. This object is a 64-bit version of ifOutOctets. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 10 } ifHCOutUcastPkts OBJECT-TYPE SYNTAX Counter64 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of packets that higher-level protocols requested be transmitted, and which were not addressed to a multicast or broadcast address at this sub-layer, including those that were discarded or not sent. This object is a 64-bit version of ifOutUcastPkts. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 11 } ifHCOutMulticastPkts OBJECT-TYPE SYNTAX Counter64 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of packets that higher-level protocols requested be transmitted, and which were addressed to a multicast address at this sub-layer, including those that were discarded or not sent. For a MAC layer protocol, this includes both Group and Functional addresses. This object is a 64-bit version of ifOutMulticastPkts. Discontinuities in the value of this counter can occur at McCloghrie & Kastenholz [Page 46]
Internet Draft Interfaces Group MIB October 1999 re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 12 } ifHCOutBroadcastPkts OBJECT-TYPE SYNTAX Counter64 MAX-ACCESS read-only STATUS current DESCRIPTION "The total number of packets that higher-level protocols requested be transmitted, and which were addressed to a broadcast address at this sub-layer, including those that were discarded or not sent. This object is a 64-bit version of ifOutBroadcastPkts. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime." ::= { ifXEntry 13 } ifLinkUpDownTrapEnable OBJECT-TYPE SYNTAX INTEGER { enabled(1), disabled(2) } MAX-ACCESS read-write STATUS current DESCRIPTION "Indicates whether linkUp/linkDown traps should be generated for this interface. By default, this object should have the value enabled(1) for interfaces which do not operate on 'top' of any other interface (as defined in the ifStackTable), and disabled(2) otherwise." ::= { ifXEntry 14 } ifHighSpeed OBJECT-TYPE SYNTAX Gauge32 MAX-ACCESS read-only STATUS current DESCRIPTION "An estimate of the interface's current bandwidth in units of 1,000,000 bits per second. If this object reports a value of `n' then the speed of the interface is somewhere in the range of `n-500,000' to `n+499,999'. For interfaces McCloghrie & Kastenholz [Page 47]
Internet Draft Interfaces Group MIB October 1999 which do not vary in bandwidth or for those where no accurate estimation can be made, this object should contain the nominal bandwidth. For a sub-layer which has no concept of bandwidth, this object should be zero." ::= { ifXEntry 15 } ifPromiscuousMode OBJECT-TYPE SYNTAX TruthValue MAX-ACCESS read-write STATUS current DESCRIPTION "This object has a value of false(2) if this interface only accepts packets/frames that are addressed to this station. This object has a value of true(1) when the station accepts all packets/frames transmitted on the media. The value true(1) is only legal on certain types of media. If legal, setting this object to a value of true(1) may require the interface to be reset before becoming effective. The value of ifPromiscuousMode does not affect the reception of broadcast and multicast packets/frames by the interface." ::= { ifXEntry 16 } ifConnectorPresent OBJECT-TYPE SYNTAX TruthValue MAX-ACCESS read-only STATUS current DESCRIPTION "This object has the value 'true(1)' if the interface sublayer has a physical connector and the value 'false(2)' otherwise." ::= { ifXEntry 17 } ifAlias OBJECT-TYPE SYNTAX DisplayString (SIZE(0..64)) MAX-ACCESS read-write STATUS current DESCRIPTION "This object is an 'alias' name for the interface as specified by a network manager, and provides a non-volatile 'handle' for the interface. On the first instantiation of an interface, the value of ifAlias associated with that interface is the zero-length string. As and when a value is written into an instance of McCloghrie & Kastenholz [Page 48]
Internet Draft Interfaces Group MIB October 1999 ifAlias through a network management set operation, then the agent must retain the supplied value in the ifAlias instance associated with the same interface for as long as that interface remains instantiated, including across all re- initializations/reboots of the network management system, including those which result in a change of the interface's ifIndex value. An example of the value which a network manager might store in this object for a WAN interface is the (Telco's) circuit number/identifier of the interface. Some agents may support write-access only for interfaces having particular values of ifType. An agent which supports write access to this object is required to keep the value in non-volatile storage, but it may limit the length of new values depending on how much storage is already occupied by the current values for other interfaces." ::= { ifXEntry 18 } ifCounterDiscontinuityTime OBJECT-TYPE SYNTAX TimeStamp MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime on the most recent occasion at which any one or more of this interface's counters suffered a discontinuity. The relevant counters are the specific instances associated with this interface of any Counter32 or Counter64 object contained in the ifTable or ifXTable. If no such discontinuities have occurred since the last re- initialization of the local management subsystem, then this object contains a zero value." ::= { ifXEntry 19 } McCloghrie & Kastenholz [Page 49]
Internet Draft Interfaces Group MIB October 1999 -- The Interface Stack Group -- -- Implementation of this group is optional, but strongly recommended -- for all systems -- ifStackTable OBJECT-TYPE SYNTAX SEQUENCE OF IfStackEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "The table containing information on the relationships between the multiple sub-layers of network interfaces. In particular, it contains information on which sub-layers run 'on top of' which other sub-layers, where each sub-layer corresponds to a conceptual row in the ifTable. For example, when the sub-layer with ifIndex value x runs over the sub-layer with ifIndex value y, then this table contains: ifStackStatus.x.y=active For each ifIndex value, I, which identifies an active interface, there are always at least two instantiated rows in this table associated with I. For one of these rows, I is the value of ifStackHigherLayer; for the other, I is the value of ifStackLowerLayer. (If I is not involved in multiplexing, then these are the only two rows associated with I.) For example, two rows exist even for an interface which has no others stacked on top or below it: ifStackStatus.0.x=active ifStackStatus.x.0=active " ::= { ifMIBObjects 2 } ifStackEntry OBJECT-TYPE SYNTAX IfStackEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Information on a particular relationship between two sub- layers, specifying that one sub-layer runs on 'top' of the McCloghrie & Kastenholz [Page 50]
Internet Draft Interfaces Group MIB October 1999 other sub-layer. Each sub-layer corresponds to a conceptual row in the ifTable." INDEX { ifStackHigherLayer, ifStackLowerLayer } ::= { ifStackTable 1 } IfStackEntry ::= SEQUENCE { ifStackHigherLayer InterfaceIndexOrZero, ifStackLowerLayer InterfaceIndexOrZero, ifStackStatus RowStatus } ifStackHigherLayer OBJECT-TYPE SYNTAX InterfaceIndexOrZero MAX-ACCESS not-accessible STATUS current DESCRIPTION "The value of ifIndex corresponding to the higher sub-layer of the relationship, i.e., the sub-layer which runs on 'top' of the sub-layer identified by the corresponding instance of ifStackLowerLayer. If there is no higher sub-layer (below the internetwork layer), then this object has the value 0." ::= { ifStackEntry 1 } ifStackLowerLayer OBJECT-TYPE SYNTAX InterfaceIndexOrZero MAX-ACCESS not-accessible STATUS current DESCRIPTION "The value of ifIndex corresponding to the lower sub-layer of the relationship, i.e., the sub-layer which runs 'below' the sub-layer identified by the corresponding instance of ifStackHigherLayer. If there is no lower sub-layer, then this object has the value 0." ::= { ifStackEntry 2 } ifStackStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION McCloghrie & Kastenholz [Page 51]
Internet Draft Interfaces Group MIB October 1999 "The status of the relationship between two sub-layers. Changing the value of this object from 'active' to 'notInService' or 'destroy' will likely have consequences up and down the interface stack. Thus, write access to this object is likely to be inappropriate for some types of interfaces, and many implementations will choose not to support write-access for any type of interface." ::= { ifStackEntry 3 } ifStackLastChange OBJECT-TYPE SYNTAX TimeTicks MAX-ACCESS read-only STATUS current DESCRIPTION "The value of sysUpTime at the time of the last change of the (whole) interface stack. A change of the interface stack is defined to be any creation, deletion, or change in value of any instance of ifStackStatus. If the interface stack has been unchanged since the last re-initialization of the local network management subsystem, then this object contains a zero value." ::= { ifMIBObjects 6 } -- Generic Receive Address Table -- -- This group of objects is mandatory for all types of -- interfaces which can receive packets/frames addressed to -- more than one address. -- -- This table replaces the ifExtnsRcvAddr table. The main -- difference is that this table makes use of the RowStatus -- textual convention, while ifExtnsRcvAddr did not. ifRcvAddressTable OBJECT-TYPE SYNTAX SEQUENCE OF IfRcvAddressEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "This table contains an entry for each address (broadcast, multicast, or uni-cast) for which the system will receive packets/frames on a particular interface, except as follows: - for an interface operating in promiscuous mode, entries McCloghrie & Kastenholz [Page 52]
Internet Draft Interfaces Group MIB October 1999 are only required for those addresses for which the system would receive frames were it not operating in promiscuous mode. - for 802.5 functional addresses, only one entry is required, for the address which has the functional address bit ANDed with the bit mask of all functional addresses for which the interface will accept frames. A system is normally able to use any unicast address which corresponds to an entry in this table as a source address." ::= { ifMIBObjects 4 } ifRcvAddressEntry OBJECT-TYPE SYNTAX IfRcvAddressEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A list of objects identifying an address for which the system will accept packets/frames on the particular interface identified by the index value ifIndex." INDEX { ifIndex, ifRcvAddressAddress } ::= { ifRcvAddressTable 1 } IfRcvAddressEntry ::= SEQUENCE { ifRcvAddressAddress PhysAddress, ifRcvAddressStatus RowStatus, ifRcvAddressType INTEGER } ifRcvAddressAddress OBJECT-TYPE SYNTAX PhysAddress MAX-ACCESS not-accessible STATUS current DESCRIPTION "An address for which the system will accept packets/frames on this entry's interface." ::= { ifRcvAddressEntry 1 } ifRcvAddressStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION McCloghrie & Kastenholz [Page 53]
Internet Draft Interfaces Group MIB October 1999 "This object is used to create and delete rows in the ifRcvAddressTable." ::= { ifRcvAddressEntry 2 } ifRcvAddressType OBJECT-TYPE SYNTAX INTEGER { other(1), volatile(2), nonVolatile(3) } MAX-ACCESS read-create STATUS current DESCRIPTION "This object has the value nonVolatile(3) for those entries in the table which are valid and will not be deleted by the next restart of the managed system. Entries having the value volatile(2) are valid and exist, but have not been saved, so that will not exist after the next restart of the managed system. Entries having the value other(1) are valid and exist but are not classified as to whether they will continue to exist after the next restart." DEFVAL { volatile } ::= { ifRcvAddressEntry 3 } McCloghrie & Kastenholz [Page 54]
Internet Draft Interfaces Group MIB October 1999 -- definition of interface-related traps. linkDown NOTIFICATION-TYPE OBJECTS { ifIndex, ifAdminStatus, ifOperStatus } STATUS current DESCRIPTION "A linkDown trap signifies that the SNMP entity, acting in an agent role, has detected that the ifOperStatus object for one of its communication links is about to enter the down state from some other state (but not from the notPresent state). This other state is indicated by the included value of ifOperStatus." ::= { snmpTraps 3 } linkUp NOTIFICATION-TYPE OBJECTS { ifIndex, ifAdminStatus, ifOperStatus } STATUS current DESCRIPTION "A linkUp trap signifies that the SNMP entity, acting in an agent role, has detected that the ifOperStatus object for one of its communication links left the down state and transitioned into some other state (but not into the notPresent state). This other state is indicated by the included value of ifOperStatus." ::= { snmpTraps 4 } McCloghrie & Kastenholz [Page 55]
Internet Draft Interfaces Group MIB October 1999 -- conformance information ifConformance OBJECT IDENTIFIER ::= { ifMIB 2 } ifGroups OBJECT IDENTIFIER ::= { ifConformance 1 } ifCompliances OBJECT IDENTIFIER ::= { ifConformance 2 } -- compliance statements ifCompliance3 MODULE-COMPLIANCE STATUS current DESCRIPTION "The compliance statement for SNMP entities which have network interfaces." MODULE -- this module MANDATORY-GROUPS { ifGeneralInformationGroup, linkUpDownNotificationsGroup, ifCounterDiscontinuityGroup } -- The groups: -- ifFixedLengthGroup -- ifHCFixedLengthGroup -- ifPacketGroup -- ifHCPacketGroup -- ifVHCPacketGroup -- are mutually exclusive; at most one of these groups is implemented -- for a particular interface GROUP ifFixedLengthGroup DESCRIPTION "This group is mandatory for those network interfaces which are character-oriented or transmit data in fixed-length transmission units, and for which the value of the corresponding instance of ifSpeed is less than or equal to 20,000,000 bits/second." GROUP ifHCFixedLengthGroup DESCRIPTION "This group is mandatory for those network interfaces which are character-oriented or transmit data in fixed-length transmission units, and for which the value of the corresponding instance of ifSpeed is greater than 20,000,000 bits/second." McCloghrie & Kastenholz [Page 56]
Internet Draft Interfaces Group MIB October 1999 GROUP ifPacketGroup DESCRIPTION "This group is mandatory for those network interfaces which are packet-oriented, and for which the value of the corresponding instance of ifSpeed is less than or equal to 20,000,000 bits/second." GROUP ifHCPacketGroup DESCRIPTION "This group is mandatory only for those network interfaces which are packet-oriented and for which the value of the corresponding instance of ifSpeed is greater than 20,000,000 bits/second but less than or equal to 650,000,000 bits/second." GROUP ifVHCPacketGroup DESCRIPTION "This group is mandatory only for those network interfaces which are packet-oriented and for which the value of the corresponding instance of ifSpeed is greater than 650,000,000 bits/second." GROUP ifRcvAddressGroup DESCRIPTION "The applicability of this group MUST be defined by the media-specific MIBs. Media-specific MIBs must define the exact meaning, use, and semantics of the addresses in this group." OBJECT ifLinkUpDownTrapEnable MIN-ACCESS read-only DESCRIPTION "Write access is not required." OBJECT ifPromiscuousMode MIN-ACCESS read-only DESCRIPTION "Write access is not required." OBJECT ifAdminStatus SYNTAX INTEGER { up(1), down(2) } MIN-ACCESS read-only DESCRIPTION "Write access is not required, nor is support for the value testing(3)." McCloghrie & Kastenholz [Page 57]
Internet Draft Interfaces Group MIB October 1999 OBJECT ifAlias MIN-ACCESS read-only DESCRIPTION "Write access is not required." ::= { ifCompliances 3 } McCloghrie & Kastenholz [Page 58]
Internet Draft Interfaces Group MIB October 1999 -- units of conformance ifGeneralInformationGroup OBJECT-GROUP OBJECTS { ifIndex, ifDescr, ifType, ifSpeed, ifPhysAddress, ifAdminStatus, ifOperStatus, ifLastChange, ifLinkUpDownTrapEnable, ifConnectorPresent, ifHighSpeed, ifName, ifNumber, ifAlias, ifTableLastChange } STATUS current DESCRIPTION "A collection of objects providing information applicable to all network interfaces." ::= { ifGroups 10 } -- the following five groups are mutually exclusive; at most -- one of these groups is implemented for any interface ifFixedLengthGroup OBJECT-GROUP OBJECTS { ifInOctets, ifOutOctets, ifInUnknownProtos, ifInErrors, ifOutErrors } STATUS current DESCRIPTION "A collection of objects providing information specific to non-high speed (non-high speed interfaces transmit and receive at speeds less than or equal to 20,000,000 bits/second) character-oriented or fixed-length-transmission network interfaces." ::= { ifGroups 2 } ifHCFixedLengthGroup OBJECT-GROUP OBJECTS { ifHCInOctets, ifHCOutOctets, ifInOctets, ifOutOctets, ifInUnknownProtos, ifInErrors, ifOutErrors } STATUS current DESCRIPTION "A collection of objects providing information specific to high speed (greater than 20,000,000 bits/second) character- oriented or fixed-length-transmission network interfaces." ::= { ifGroups 3 } ifPacketGroup OBJECT-GROUP OBJECTS { ifInOctets, ifOutOctets, ifInUnknownProtos, ifInErrors, ifOutErrors, ifMtu, ifInUcastPkts, ifInMulticastPkts, ifInBroadcastPkts, ifInDiscards, McCloghrie & Kastenholz [Page 59]
Internet Draft Interfaces Group MIB October 1999 ifOutUcastPkts, ifOutMulticastPkts, ifOutBroadcastPkts, ifOutDiscards, ifPromiscuousMode } STATUS current DESCRIPTION "A collection of objects providing information specific to non-high speed (non-high speed interfaces transmit and receive at speeds less than or equal to 20,000,000 bits/second) packet-oriented network interfaces." ::= { ifGroups 4 } ifHCPacketGroup OBJECT-GROUP OBJECTS { ifHCInOctets, ifHCOutOctets, ifInOctets, ifOutOctets, ifInUnknownProtos, ifInErrors, ifOutErrors, ifMtu, ifInUcastPkts, ifInMulticastPkts, ifInBroadcastPkts, ifInDiscards, ifOutUcastPkts, ifOutMulticastPkts, ifOutBroadcastPkts, ifOutDiscards, ifPromiscuousMode } STATUS current DESCRIPTION "A collection of objects providing information specific to high speed (greater than 20,000,000 bits/second but less than or equal to 650,000,000 bits/second) packet-oriented network interfaces." ::= { ifGroups 5 } ifVHCPacketGroup OBJECT-GROUP OBJECTS { ifHCInUcastPkts, ifHCInMulticastPkts, ifHCInBroadcastPkts, ifHCOutUcastPkts, ifHCOutMulticastPkts, ifHCOutBroadcastPkts, ifHCInOctets, ifHCOutOctets, ifInOctets, ifOutOctets, ifInUnknownProtos, ifInErrors, ifOutErrors, ifMtu, ifInUcastPkts, ifInMulticastPkts, ifInBroadcastPkts, ifInDiscards, ifOutUcastPkts, ifOutMulticastPkts, ifOutBroadcastPkts, ifOutDiscards, ifPromiscuousMode } STATUS current DESCRIPTION "A collection of objects providing information specific to higher speed (greater than 650,000,000 bits/second) packet- oriented network interfaces." McCloghrie & Kastenholz [Page 60]
Internet Draft Interfaces Group MIB October 1999 ::= { ifGroups 6 } ifRcvAddressGroup OBJECT-GROUP OBJECTS { ifRcvAddressStatus, ifRcvAddressType } STATUS current DESCRIPTION "A collection of objects providing information on the multiple addresses which an interface receives." ::= { ifGroups 7 } ifStackGroup2 OBJECT-GROUP OBJECTS { ifStackStatus, ifStackLastChange } STATUS current DESCRIPTION "A collection of objects providing information on the layering of MIB-II interfaces." ::= { ifGroups 11 } ifCounterDiscontinuityGroup OBJECT-GROUP OBJECTS { ifCounterDiscontinuityTime } STATUS current DESCRIPTION "A collection of objects providing information specific to interface counter discontinuities." ::= { ifGroups 13 } linkUpDownNotificationsGroup NOTIFICATION-GROUP NOTIFICATIONS { linkUp, linkDown } STATUS current DESCRIPTION "The notifications which indicate specific changes in the value of ifOperStatus." ::= { ifGroups 14 } McCloghrie & Kastenholz [Page 61]
Internet Draft Interfaces Group MIB October 1999 -- Deprecated Definitions - Objects -- -- The Interface Test Table -- -- This group of objects is optional. However, a media-specific -- MIB may make implementation of this group mandatory. -- -- This table replaces the ifExtnsTestTable -- ifTestTable OBJECT-TYPE SYNTAX SEQUENCE OF IfTestEntry MAX-ACCESS not-accessible STATUS deprecated DESCRIPTION "This table contains one entry per interface. It defines objects which allow a network manager to instruct an agent to test an interface for various faults. Tests for an interface are defined in the media-specific MIB for that interface. After invoking a test, the object ifTestResult can be read to determine the outcome. If an agent can not perform the test, ifTestResult is set to so indicate. The object ifTestCode can be used to provide further test- specific or interface-specific (or even enterprise-specific) information concerning the outcome of the test. Only one test can be in progress on each interface at any one time. If one test is in progress when another test is invoked, the second test is rejected. Some agents may reject a test when a prior test is active on another interface. Before starting a test, a manager-station must first obtain 'ownership' of the entry in the ifTestTable for the interface to be tested. This is accomplished with the ifTestId and ifTestStatus objects as follows: try_again: get (ifTestId, ifTestStatus) while (ifTestStatus != notInUse) /* * Loop while a test is running or some other * manager is configuring a test. */ short delay McCloghrie & Kastenholz [Page 62]
Internet Draft Interfaces Group MIB October 1999 get (ifTestId, ifTestStatus) } /* * Is not being used right now -- let's compete * to see who gets it. */ lock_value = ifTestId if ( set(ifTestId = lock_value, ifTestStatus = inUse, ifTestOwner = 'my-IP-address') == FAILURE) /* * Another manager got the ifTestEntry -- go * try again */ goto try_again; /* * I have the lock */ set up any test parameters. /* * This starts the test */ set(ifTestType = test_to_run); wait for test completion by polling ifTestResult when test completes, agent sets ifTestResult agent also sets ifTestStatus = 'notInUse' retrieve any additional test results, and ifTestId if (ifTestId == lock_value+1) results are valid A manager station first retrieves the value of the appropriate ifTestId and ifTestStatus objects, periodically repeating the retrieval if necessary, until the value of ifTestStatus is 'notInUse'. The manager station then tries to set the same ifTestId object to the value it just retrieved, the same ifTestStatus object to 'inUse', and the corresponding ifTestOwner object to a value indicating itself. If the set operation succeeds then the manager has obtained ownership of the ifTestEntry, and the value of the McCloghrie & Kastenholz [Page 63]
Internet Draft Interfaces Group MIB October 1999 ifTestId object is incremented by the agent (per the semantics of TestAndIncr). Failure of the set operation indicates that some other manager has obtained ownership of the ifTestEntry. Once ownership is obtained, any test parameters can be setup, and then the test is initiated by setting ifTestType. On completion of the test, the agent sets ifTestStatus to 'notInUse'. Once this occurs, the manager can retrieve the results. In the (rare) event that the invocation of tests by two network managers were to overlap, then there would be a possibility that the first test's results might be overwritten by the second test's results prior to the first results being read. This unlikely circumstance can be detected by a network manager retrieving ifTestId at the same time as retrieving the test results, and ensuring that the results are for the desired request. If ifTestType is not set within an abnormally long period of time after ownership is obtained, the agent should time-out the manager, and reset the value of the ifTestStatus object back to 'notInUse'. It is suggested that this time-out period be 5 minutes. In general, a management station must not retransmit a request to invoke a test for which it does not receive a response; instead, it properly inspects an agent's MIB to determine if the invocation was successful. Only if the invocation was unsuccessful, is the invocation request retransmitted. Some tests may require the interface to be taken off-line in order to execute them, or may even require the agent to reboot after completion of the test. In these circumstances, communication with the management station invoking the test may be lost until after completion of the test. An agent is not required to support such tests. However, if such tests are supported, then the agent should make every effort to transmit a response to the request which invoked the test prior to losing communication. When the agent is restored to normal service, the results of the test are properly made available in the appropriate objects. Note that this requires that the ifIndex value assigned to an interface must be unchanged even if the test causes a reboot. An agent must reject any test for which it cannot, McCloghrie & Kastenholz [Page 64]
Internet Draft Interfaces Group MIB October 1999 perhaps due to resource constraints, make available at least the minimum amount of information after that test completes." ::= { ifMIBObjects 3 } ifTestEntry OBJECT-TYPE SYNTAX IfTestEntry MAX-ACCESS not-accessible STATUS deprecated DESCRIPTION "An entry containing objects for invoking tests on an interface." AUGMENTS { ifEntry } ::= { ifTestTable 1 } IfTestEntry ::= SEQUENCE { ifTestId TestAndIncr, ifTestStatus INTEGER, ifTestType AutonomousType, ifTestResult INTEGER, ifTestCode OBJECT IDENTIFIER, ifTestOwner OwnerString } ifTestId OBJECT-TYPE SYNTAX TestAndIncr MAX-ACCESS read-write STATUS deprecated DESCRIPTION "This object identifies the current invocation of the interface's test." ::= { ifTestEntry 1 } ifTestStatus OBJECT-TYPE SYNTAX INTEGER { notInUse(1), inUse(2) } MAX-ACCESS read-write STATUS deprecated DESCRIPTION "This object indicates whether or not some manager currently has the necessary 'ownership' required to invoke a test on this interface. A write to this object is only successful when it changes its value from 'notInUse(1)' to 'inUse(2)'. After completion of a test, the agent resets the value back to 'notInUse(1)'." McCloghrie & Kastenholz [Page 65]
Internet Draft Interfaces Group MIB October 1999 ::= { ifTestEntry 2 } ifTestType OBJECT-TYPE SYNTAX AutonomousType MAX-ACCESS read-write STATUS deprecated DESCRIPTION "A control variable used to start and stop operator- initiated interface tests. Most OBJECT IDENTIFIER values assigned to tests are defined elsewhere, in association with specific types of interface. However, this document assigns a value for a full-duplex loopback test, and defines the special meanings of the subject identifier: noTest OBJECT IDENTIFIER ::= { 0 0 } When the value noTest is written to this object, no action is taken unless a test is in progress, in which case the test is aborted. Writing any other value to this object is only valid when no test is currently in progress, in which case the indicated test is initiated. When read, this object always returns the most recent value that ifTestType was set to. If it has not been set since the last initialization of the network management subsystem on the agent, a value of noTest is returned." ::= { ifTestEntry 3 } ifTestResult OBJECT-TYPE SYNTAX INTEGER { none(1), -- no test yet requested success(2), inProgress(3), notSupported(4), unAbleToRun(5), -- due to state of system aborted(6), failed(7) } MAX-ACCESS read-only STATUS deprecated DESCRIPTION "This object contains the result of the most recently requested test, or the value none(1) if no tests have been requested since the last reset. Note that this facility provides no provision for saving the results of one test McCloghrie & Kastenholz [Page 66]
Internet Draft Interfaces Group MIB October 1999 when starting another, as could be required if used by multiple managers concurrently." ::= { ifTestEntry 4 } ifTestCode OBJECT-TYPE SYNTAX OBJECT IDENTIFIER MAX-ACCESS read-only STATUS deprecated DESCRIPTION "This object contains a code which contains more specific information on the test result, for example an error-code after a failed test. Error codes and other values this object may take are specific to the type of interface and/or test. The value may have the semantics of either the AutonomousType or InstancePointer textual conventions as defined in RFC 2579. The identifier: testCodeUnknown OBJECT IDENTIFIER ::= { 0 0 } is defined for use if no additional result code is available." ::= { ifTestEntry 5 } ifTestOwner OBJECT-TYPE SYNTAX OwnerString MAX-ACCESS read-write STATUS deprecated DESCRIPTION "The entity which currently has the 'ownership' required to invoke a test on this interface." ::= { ifTestEntry 6 } McCloghrie & Kastenholz [Page 67]
Internet Draft Interfaces Group MIB October 1999 -- Deprecated Definitions - Groups ifGeneralGroup OBJECT-GROUP OBJECTS { ifDescr, ifType, ifSpeed, ifPhysAddress, ifAdminStatus, ifOperStatus, ifLastChange, ifLinkUpDownTrapEnable, ifConnectorPresent, ifHighSpeed, ifName } STATUS deprecated DESCRIPTION "A collection of objects deprecated in favour of ifGeneralInformationGroup." ::= { ifGroups 1 } ifTestGroup OBJECT-GROUP OBJECTS { ifTestId, ifTestStatus, ifTestType, ifTestResult, ifTestCode, ifTestOwner } STATUS deprecated DESCRIPTION "A collection of objects providing the ability to invoke tests on an interface." ::= { ifGroups 8 } ifStackGroup OBJECT-GROUP OBJECTS { ifStackStatus } STATUS deprecated DESCRIPTION "The previous collection of objects providing information on the layering of MIB-II interfaces." ::= { ifGroups 9 } ifOldObjectsGroup OBJECT-GROUP OBJECTS { ifInNUcastPkts, ifOutNUcastPkts, ifOutQLen, ifSpecific } STATUS deprecated DESCRIPTION "The collection of objects deprecated from the original MIB- II interfaces group." ::= { ifGroups 12 } McCloghrie & Kastenholz [Page 68]
Internet Draft Interfaces Group MIB October 1999 -- Deprecated Definitions - Compliance ifCompliance MODULE-COMPLIANCE STATUS deprecated DESCRIPTION "A compliance statement defined in a previous version of this MIB module, for SNMP entities which have network interfaces." MODULE -- this module MANDATORY-GROUPS { ifGeneralGroup, ifStackGroup } GROUP ifFixedLengthGroup DESCRIPTION "This group is mandatory for all network interfaces which are character-oriented or transmit data in fixed-length transmission units." GROUP ifHCFixedLengthGroup DESCRIPTION "This group is mandatory only for those network interfaces which are character-oriented or transmit data in fixed- length transmission units, and for which the value of the corresponding instance of ifSpeed is greater than 20,000,000 bits/second." GROUP ifPacketGroup DESCRIPTION "This group is mandatory for all network interfaces which are packet-oriented." GROUP ifHCPacketGroup DESCRIPTION "This group is mandatory only for those network interfaces which are packet-oriented and for which the value of the corresponding instance of ifSpeed is greater than 650,000,000 bits/second." GROUP ifTestGroup DESCRIPTION "This group is optional. Media-specific MIBs which require interface tests are strongly encouraged to use this group for invoking tests and reporting results. A medium specific MIB which has mandatory tests may make implementation of this group mandatory." McCloghrie & Kastenholz [Page 69]
Internet Draft Interfaces Group MIB October 1999 GROUP ifRcvAddressGroup DESCRIPTION "The applicability of this group MUST be defined by the media-specific MIBs. Media-specific MIBs must define the exact meaning, use, and semantics of the addresses in this group." OBJECT ifLinkUpDownTrapEnable MIN-ACCESS read-only DESCRIPTION "Write access is not required." OBJECT ifPromiscuousMode MIN-ACCESS read-only DESCRIPTION "Write access is not required." OBJECT ifStackStatus SYNTAX INTEGER { active(1) } -- subset of RowStatus MIN-ACCESS read-only DESCRIPTION "Write access is not required, and only one of the six enumerated values for the RowStatus textual convention need be supported, specifically: active(1)." OBJECT ifAdminStatus SYNTAX INTEGER { up(1), down(2) } MIN-ACCESS read-only DESCRIPTION "Write access is not required, nor is support for the value testing(3)." ::= { ifCompliances 1 } ifCompliance2 MODULE-COMPLIANCE STATUS deprecated DESCRIPTION "A compliance statement defined in a previous version of this MIB module, for SNMP entities which have network interfaces." MODULE -- this module MANDATORY-GROUPS { ifGeneralInformationGroup, ifStackGroup2, ifCounterDiscontinuityGroup } GROUP ifFixedLengthGroup McCloghrie & Kastenholz [Page 70]
Internet Draft Interfaces Group MIB October 1999 DESCRIPTION "This group is mandatory for all network interfaces which are character-oriented or transmit data in fixed-length transmission units." GROUP ifHCFixedLengthGroup DESCRIPTION "This group is mandatory only for those network interfaces which are character-oriented or transmit data in fixed- length transmission units, and for which the value of the corresponding instance of ifSpeed is greater than 20,000,000 bits/second." GROUP ifPacketGroup DESCRIPTION "This group is mandatory for all network interfaces which are packet-oriented." GROUP ifHCPacketGroup DESCRIPTION "This group is mandatory only for those network interfaces which are packet-oriented and for which the value of the corresponding instance of ifSpeed is greater than 650,000,000 bits/second." GROUP ifRcvAddressGroup DESCRIPTION "The applicability of this group MUST be defined by the media-specific MIBs. Media-specific MIBs must define the exact meaning, use, and semantics of the addresses in this group." OBJECT ifLinkUpDownTrapEnable MIN-ACCESS read-only DESCRIPTION "Write access is not required." OBJECT ifPromiscuousMode MIN-ACCESS read-only DESCRIPTION "Write access is not required." OBJECT ifStackStatus SYNTAX INTEGER { active(1) } -- subset of RowStatus MIN-ACCESS read-only McCloghrie & Kastenholz [Page 71]
Internet Draft Interfaces Group MIB October 1999 DESCRIPTION "Write access is not required, and only one of the six enumerated values for the RowStatus textual convention need be supported, specifically: active(1)." OBJECT ifAdminStatus SYNTAX INTEGER { up(1), down(2) } MIN-ACCESS read-only DESCRIPTION "Write access is not required, nor is support for the value testing(3)." OBJECT ifAlias MIN-ACCESS read-only DESCRIPTION "Write access is not required." ::= { ifCompliances 2 } END McCloghrie & Kastenholz [Page 72]
Internet Draft Interfaces Group MIB October 1999 7. Acknowledgements This memo has been produced by the IETF's Interfaces MIB working-group. The original proposal evolved from conversations and discussions with many people, including at least the following: Fred Baker, Ted Brunner, Chuck Davin, Jeremy Greene, Marshall Rose, Kaj Tesink, and Dean Throop. 8. References [1] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for Describing SNMP Management Frameworks", RFC 2571, Cabletron Systems, Inc., BMC Software, Inc., IBM T. J. Watson Research, April 1999. [2] Rose, M., and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based Internets", STD 16, RFC 1155, Performance Systems International, Hughes LAN Systems, May 1990. [3] Rose, M., and K. McCloghrie, "Concise MIB Definitions", STD 16, RFC 1212, Performance Systems International, Hughes LAN Systems, March 1991. [4] M. Rose, "A Convention for Defining Traps for use with the SNMP", RFC 1215, Performance Systems International, March 1991. [5] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999. [6] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999. [7] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M. and S. Waldbusser, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999. [8] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network Management Protocol", STD 15, RFC 1157, SNMP Research, Performance Systems International, Performance Systems International, MIT Laboratory for Computer Science, May 1990. McCloghrie & Kastenholz [Page 73]
Internet Draft Interfaces Group MIB October 1999 [9] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901, SNMP Research, Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc., International Network Services, January 1996. [10] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Transport Mappings for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1906, SNMP Research, Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc., International Network Services, January 1996. [11] Case, J., Harrington D., Presuhn R., and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", RFC 2572, SNMP Research, Inc., Cabletron Systems, Inc., BMC Software, Inc., IBM T. J. Watson Research, January 1998. [12] Blumenthal, U., and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", RFC 2574, IBM T. J. Watson Research, January 1998. [13] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Protocol Operations for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1905, SNMP Research, Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc., International Network Services, January 1996. [14] Levi, D., Meyer, P., and B. Stewart, "SMPv3 Applications", RFC 2573, SNMP Research, Inc., Secure Computing Corporation, Cisco Systems, January 1998. [15] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access Control Model (VACM) for the Simple Network Management Protocol (SNMP)", RFC 2575, IBM T. J. Watson Research, BMC Software, Inc., Cisco Systems, Inc., January 1998. [16] S. Bradner, "Key words for use in RFCs to Indicate Requirements Levels", RFC 2119, Harvard University, March 1997. [17] McCloghrie, K., and M. Rose, "Management Information Base for Network Management of TCP/IP-based internets - MIB-II", RFC 1213, Hughes LAN Systems, Performance Systems International, March 1991. [18] J. Postel, "Internet Protocol", RFC 791, Information Sciences Institute, USC, September 1981. McCloghrie & Kastenholz [Page 74]
Internet Draft Interfaces Group MIB October 1999 [19] K. McCloghrie, "Extensions to the Generic-Interface MIB", RFC 1229, Hughes LAN Systems, May 1991. [20] ATM Forum Technical Committee, "LAN Emulation Client Management: Version 1.0 Specification", af-lane-0044.000, ATM Forum, September 1995. [21] B. Stewart, "Definitions of Managed Objects for Character Stream Devices using SMIv2", RFC 1658, Xyplex Inc., July 1994. [22] Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction to Version 3 of the Internet-standard Network Management Framework", RFC 2570, April 1999. McCloghrie & Kastenholz [Page 75]
Internet Draft Interfaces Group MIB October 1999 9. Security Considerations There are a number of management objects defined in this MIB that have a MAX-ACCESS clause of read-write and/or read-create. Such objects may be considered sensitive or vulnerable in some network environments. The support for SET operations in a non-secure environment without proper protection can have a negative effect on network operations. In particular, write-able objects allow an administrator to control the interfaces and to perform tests on the interfaces, and unauthorized access to these could cause a denial of service, or in combination with other (e.g., physical) security breaches, could cause unauthorized connectivity to a device. SNMPv1 by itself is not a secure environment. Even if the network itself is secure (for example by using IPSec), even then, there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB. It is recommended that the implementers consider the security features as provided by the SNMPv3 framework. Specifically, the use of the User- based Security Model RFC 2574 [12] and the View- based Access Control Model RFC 2575 [15] is recommended. It is then a customer/user responsibility to ensure that the SNMP entity giving access to an instance of this MIB, is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them. 10. Authors' Addresses Keith McCloghrie Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 Phone: 408-526-5260 Email: kzm@cisco.com" Frank Kastenholz Argon Networks 25 Porter Rd Littleton Ma 01460 McCloghrie & Kastenholz [Page 76]
Internet Draft Interfaces Group MIB October 1999 Phone: (508)685-4000 Email: kasten@argon.com McCloghrie & Kastenholz [Page 77]
Internet Draft Interfaces Group MIB October 1999 11. Changes from RFC 2233 Added linkUpDownNotificationsGroup. Changed the status of the definition of OwnerString in this MIB to be deprecated, because it is only used by ifTestOwner, which is now deprecated, and because other MIBs should import OwnerString from RFC 1757 or its successors. Added ifCompliance3 as a replacement for ifCompliance2 to omit the ifStackGroup2 group, and add linkUpDownNotificationsGroup. Also, corrected the omission of ifVHCPacketGroup, and typos in the DESCRIPTIONs of ifHCPacketGroup and ifFixedLengthGroup. Obsoleted ifCompliance2. Modified syntax of ifStackHigherLayer and ifStackLowerLayer to be InterfaceIndexOrZero. Added requirement that media-specific MIB designers specify any special conditions concerning the counting of framing characters in ifInOctets and ifOutOctets. Corrected a typo in the DESCRIPTION of the linkUp notification. Modified the introductory SNMP Network Management Framework boilerplate text. McCloghrie & Kastenholz [Page 78]
Internet Draft Interfaces Group MIB October 1999 12. Notice on Intellectual Property The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards- related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. 13. Full Copyright Statement Copyright (C) The Internet Society (1999). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK McCloghrie & Kastenholz [Page 79]
Internet Draft Interfaces Group MIB October 1999 FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." McCloghrie & Kastenholz [Page 80]
Internet Draft Interfaces Group MIB October 1999 Table of Contents 1 Introduction .................................................... 2 2 The SNMP Network Management Framework ........................... 2 3 Experience with the Interfaces Group ............................ 3 3.1 Clarifications/Revisions ...................................... 4 3.1.1 Interface Sub-Layers ........................................ 4 3.1.2 Guidance on Defining Sub-layers ............................. 7 3.1.3 Virtual Circuits ............................................ 8 3.1.4 Bit, Character, and Fixed-Length Interfaces ................. 9 3.1.5 Interface Numbering ......................................... 11 3.1.6 Counter Size ................................................ 15 3.1.7 Interface Speed ............................................. 17 3.1.8 Multicast/Broadcast Counters ................................ 18 3.1.9 Trap Enable ................................................. 19 3.1.10 Addition of New ifType values .............................. 19 3.1.11 InterfaceIndex Textual Convention .......................... 19 3.1.12 New states for IfOperStatus ................................ 20 3.1.13 IfAdminStatus and IfOperStatus ............................. 21 3.1.14 IfOperStatus in an Interface Stack ......................... 22 3.1.15 Traps ...................................................... 22 3.1.16 ifSpecific ................................................. 24 3.1.17 Creation/Deletion of Interfaces ............................ 24 3.1.18 All Values Must be Known ................................... 25 4 Media-Specific MIB Applicability ................................ 27 5 Overview ........................................................ 28 6 Interfaces Group Definitions .................................... 29 7 Acknowledgements ................................................ 73 8 References ...................................................... 73 9 Security Considerations ......................................... 76 10 Authors' Addresses ............................................. 76 11 Changes from RFC 2233 .......................................... 78 12 Notice on Intellectual Property ................................ 79 13 Full Copyright Statement ....................................... 79 McCloghrie & Kastenholz [Page 81]
