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Versions: 00 01 02 03 04 05 rfc2922                        Informational
PTOPOMIB Working Group                                     Andy Bierman
Internet Draft                                       Cisco Systems, Inc.
                                                              Ken Jones
                                                        Nortel Networks
                                                           14 June 2000


                         Physical Topology MIB


                    <draft-ietf-ptopomib-mib-05.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
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The list of current Internet-Drafts can be accessed at
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Distribution of this document is unlimited. Please send comments to the
authors.

1.  Copyright Notice

Copyright (C) The Internet Society (2000).  All Rights Reserved.














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2.  Abstract

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 physical
topology identification and discovery.

3.  Table of Contents

1 Copyright Notice ................................................    1
2 Abstract ........................................................    2
3 Table of Contents ...............................................    2
4 The SNMP Network Management Framework ...........................    2
5 Overview ........................................................    4
5.1 Terms .........................................................    4
5.2 Design Goals ..................................................    5
6 Topology Framework ..............................................    7
6.1 Devices and Topology Agents ...................................    7
6.2 Topology Mechanisms ...........................................    7
6.3 Future Considerations .........................................    8
7 Physical Topology MIB ...........................................    8
7.1 Persistent Identifiers ........................................    8
7.2 Relationship to Entity MIB ....................................    9
7.3 Relationship to Interfaces MIB ................................    9
7.4 Relationship to RMON-2 MIB ....................................   10
7.5 Relationship to Bridge MIB ....................................   10
7.6 Relationship to Repeater MIB ..................................   10
7.7 MIB Structure .................................................   10
7.7.1 ptopoData Group .............................................   10
7.7.2 ptopoGeneral Group ..........................................   11
7.7.3 ptopoConfig Group ...........................................   11
7.8 Physical Topology MIB Definitions .............................   11
8 Intellectual Property ...........................................   30
9 Acknowledgements ................................................   31
10 References .....................................................   31
11 Security Considerations ........................................   33
12 Authors' Addresses .............................................   35
13 Full Copyright Statement .......................................   36

4.  The SNMP Network Management Framework

   The SNMP Management Framework presently consists of five major
   components:







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    o   An overall architecture, described in RFC 2571 [RFC2571].

    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 [RFC1155], STD 16, RFC 1212 [RFC1212] and RFC
        1215 [RFC1215].  The second version, called SMIv2, is described
        in STD 58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and
        STD 58, RFC 2580 [RFC2580].

    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 [RFC1157].  A second version of
        the SNMP message protocol, which is not an Internet standards
        track protocol, is called SNMPv2c and described in RFC 1901
        [RFC1901] and RFC 1906 [RFC1906].  The third version of the
        message protocol is called SNMPv3 and described in RFC 1906
        [RFC1906], RFC 2572 [RFC2572] and RFC 2574 [RFC2574].

    o   Protocol operations for accessing management information.  The
        first set of protocol operations and associated PDU formats is
        described in STD 15, RFC 1157 [RFC1157].  A second set of
        protocol operations and associated PDU formats is described in
        RFC 1905 [RFC1905].

    o   A set of fundamental applications described in RFC 2573
        [RFC2573] and the view-based access control mechanism described
        in RFC 2575 [RFC2575].

   A more detailed introduction to the current SNMP Management Framework
   can be found in RFC 2570 [RFC2570].

   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 (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.





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5.  Overview

There is a need for a standardized means of representing the physical
network connections pertaining to a given management domain.  The
Physical Topology MIB (PTOPO-MIB) provides a standard way to identify
connections between network ports and to discover network addresses of
SNMP agents containing management information associated with each port.

A topology mechanism is used to discover the information required by the
PTOPO-MIB.  There is a need for a standardized topology mechanism to
increase the likelihood of multi-vendor interoperability of such
physical topology management information.  The PTOPO-MIB does not,
however, specify or restrict the discovery mechanism(s) used for an
implementation of the PTOPO-MIB.  Topology mechanisms exist for certain
media types (such as FDDI) and proprietary mechanisms exist for other
media such as shared media Ethernet, switched Ethernet, and Token Ring.
Rather than specifying mechanisms for each type of technology, the
PTOPO-MIB allows co-existence of multiple topology mechanisms. The
required objects of the PTOPO-MIB define the core requirements for any
topology mechanism.

The scope of the physical topology (PTOPO) mechanism is the
identification of connections between two network ports. Network
addresses of SNMP agents containing management information associated
with each port can also be identified.

5.1.  Terms

Some terms are used throughout this document:

Physical Topology
     Physical topology represents the topology model for layer 1 of the
     OSI stack - the physical layer.  Physical topology consists of
     identifying the devices on the network and how they are physically
     interconnected.  By definition of this document, physical topology
     does not imply a physical relationship between ports on the same
     device.  Other means exist for determining these relationships
     (e.g., Entity MIB [RFC2737]). exist for determining these
     relationships Note that physical topology is independent of logical
     topology, which associates ports based on higher layer attributes,
     such as network layer address.

Chassis
     A chassis is a physical component which contains other physical
     components.  It is identified by an entPhysicalEntry with an





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     entPhysicalClass value of 'chassis(3)' and an
     entPhysicalContainedIn value of zero.  A chassis identifier
     consists of a globally unique DisplayString.

Local Chassis
     The particular chassis containing the SNMP agent implementing the
     PTOPO MIB.

Port A port is a physical component which can be connected to another
     port through some medium.  It is identified by an entPhysicalEntry
     with an entPhysicalClass value of 'port(10)'.  A port identifier
     consists of a DisplayString which must be unique within the context
     of the chassis which contains the port.

Connection Endpoint
     A connection endpoint consists of a physical port, which is
     contained within a single physical chassis.

Connection Endpoint Identifier
     A connection endpoint is identified by a globally unique chassis
     identifier and a port identifier unique within the associated
     chassis.

Connection
     A connection consists of two physical ports, and the attached
     physical medium, configured for the purpose of transferring network
     traffic between the ports.  A connection is identified by its
     endpoint identifiers.

Non-local Connection
     A connection for which neither endpoint is located on the local
     chassis.

Cloud
     A cloud identifies a portion of the topology for which insufficient
     information is known to completely infer the interconnection of
     devices that make up that portion of the topology.

5.2.  Design Goals

Several factors influenced the design of this physical topology
function:

   - Simplicity
     The physical topology discovery function should be as simple as





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     possible, exposing only the information needed to identify
     connection endpoints and the SNMP agent(s) associated with each
     connection endpoint.

   - Completeness
     At least one standard discovery protocol capable of supporting the
     standard physical topology MIB must be defined.  Multi-vendor
     interoperability will not be achievable unless a simple and
     extensible discovery protocol is available.  However, the PTOPO MIB
     should not specify or restrict the topology discovery mechanisms an
     agent can use.

   - No Functional Overlap
     Existing standard MIBs should be utilized whenever possible.
     Physical topology information is tightly coupled to functionality
     found in the Interfaces MIB [RFC2233] and Entity MIB [RFC2737].
     New physical topology MIB objects should not duplicate these MIBs.

   - Identifier Stability
     Connection endpoint identifiers must be persistent (i.e. stable
     across device reboots). Dynamic primary key objects like ifIndex
     and entPhysicalIndex are not suitable for table indices in a
     physical topology MIB that is replicated and distributed throughout
     a managed system.

   - Identifier Flexibility
     Persistent string-based component identifiers should be supported
     from many sources. Chassis identifiers may be found in the Entity
     MIB [RFC2737], and port identifiers may be found in the Interfaces
     MIB [RFC2233] or Entity MIB [RFC2737].

   - Partial Topology Support
     Physical topology data for remote components may only be partially
     available to an agent.  An enumerated INTEGER hierarchy of
     component identifier types allows for incomplete physical
     connection identifier information to be substituted with secondary
     information such as unicast source MAC address or network address
     associated with a particular port.  A PTOPO Agent maintains
     information derived from the 'best' source of information for each
     connection.  If a 'better' identifier source is detected, the PTOPO
     entries are updated accordingly.  It is an implementation specific
     matter whether a PTOPO agent replaces 'old' entries or retains
     them, however an agent must remove information known to be
     incorrect.






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   - Low Polling Impact
     Physical topology polling should be minimized through techniques
     such as TimeFiltered data tables (from RMON-2 [RFC2021]), and last-
     change notifications.

6.  Topology Framework

This section describes the physical topology framework in detail.

6.1.  Devices and Topology Agents

The network devices, along with their physical connectivity, make up the
physical topology. Some of these devices (but maybe not all) provide
management agents that report their local physical topology information
to a manager via the physical topology MIB.

These devices include communication infrastructure devices, such as
hubs, switches, and routers, as well as 'leaf' devices such as
workstations, printers, and servers.  Generally, user data passes
through infrastructure devices while leaf devices are sources and sinks
of data.  Both types of devices may implement the physical topology MIB,
although implementation within leaf devices is much less critical.

Each managed device collects physical topology information from the
network, based on the topology mechanism(s) it is configured to use.
The data represents this agent's local view of the physical network.
Part of the topology data collected must include the identification of
other local agents which may contain additional topology information.
The definition of 'local' varies based on the topology mechanism or
mechanisms being used.

6.2.  Topology Mechanisms

A topology mechanism is a means, possibly requiring some sort of
protocol, by which devices determine topology information.  The
{topology mechanism must provide sufficient information to populate the
MIB described later in this document.}

Topology mechanisms can be active or passive.  Active mechanisms require
a device to send and receive topology protocol packets.  These packets
provide the device ID of the source of the packet and may also indicate
out which port the packet was transmitted.  When receiving these
packets, devices typically are required to identify on which port that
packet was received.






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Passive mechanisms take advantage of data on the network to populate the
topology MIB.  By maintaining a list of device identifiers seen on each
port of all devices in a network, it is possible to populate the PTOPO-
MIB.

Many instances of a particular topology mechanism may be in use on a
given network, and many different mechanisms may be employed.  In some
cases, multiple mechanisms may overlap across part of the physical
topology with individual ports supporting more than one topology
mechanism.  In general, this simply allows the port to collect more
robust topology information.  Agents may need to be configured so that
they know which mechanism(s) are in use on any given portion of the
network.

Most topology mechanisms need to be bounded to a subset of the network
to contain their impact on the network and limit the size of topology
tables maintained by the agent. Topology mechanisms are often naturally
bounded by the media on which they run (e.g. FDDI topology mechanism) or
by routers in the network that intentionally block the mechanism from
crossing into other parts of the network.

6.3.  Future Considerations

While the framework presented here is focused on physical topology, it
may well be that the topology mechanisms and MIB described could be
extended to include logical topology information as well.  That is not a
focus of this memo.

7.  Physical Topology MIB

This section describes and defines the Physical Topology MIB.

7.1.  Persistent Identifiers

The PTOPO MIB utilizes non-volatile identifiers to distinguish
individual chassis and port components.  These identifiers are
associated with external objects in order to relate topology information
to the existing managed objects.

In particular, an object from the Entity MIB [RFC2737] or Interfaces MIB
[RFC2233] can be used as the 'reference-point' for a connection
component identifier.

The Physical Topology MIB uses two identifier types pertaining to the
PTOPO MIB:





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   - globally unique chassis identifiers.

   - port identifiers; unique only within the chassis which contains the
     port.

Identifiers are stored as OCTET STRINGs, which are limited to 32 bytes
in length, This supports flexible naming conventions and constrains the
non-volatile storage requirements for an agent.

7.2.  Relationship to Entity MIB

The first version of the Entity MIB [RFC2037] allows the physical
component inventory and hierarchy to be identified.  However, this MIB
does not provide persistent component identifiers, which are required
for the PTOPO MIB.  Therefore, version 2 of the Entity MIB [RFC2737] is
required to support that feature.  Specifically, the entPhysicalAlias
object is utilized as a persistent chassis identifier.

For agents implementing the PTOPO MIB, this new object must be used to
represent the chassis identifier.  Port identifiers can be based on the
entPhysicalAlias object associated with the port, but only if the port
is not represented as an interface in the ifXTable.

Implementation of the entPhysicalGroup [RFC2737] and the
entPhysicalAlias object [RFC2737] are mandatory for SNMP agents which
implement the PTOPO MIB.  No other objects must be implemented from
these MIBs to support the physical topology function.

7.3.  Relationship to Interfaces MIB

The PTOPO MIB requires a persistent identifier for each port.  The
Interfaces MIB [RFC2233] provides a standard mechanism for managing
network interfaces.  Unfortunately, not all ports which may be
represented in the PTOPO MIB are also represented in the Interfaces MIB
(e.g., repeater ports).

For agents which implement the PTOPO MIB, for each port also represented
in the Interfaces MIB, the agent must use the associated ifAlias value
for the port identifier.  For each port not represented in the
Interfaces MIB, the associated entPhysicalAlias value must be used for
the port identifier.  Note that the PTOPO MIB requires only minimal
support from the Interfaces MIB. Specifically, the
'ifGeneralInformationGroup' level of conformance must be provided for
each port also identified in the PTOPO MIB. The agent may choose to
support these objects with read-only access, as specified in the





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conformance section of the Interfaces MIB.

7.4.  Relationship to RMON-2 MIB

The RMON-2 MIB [RFC2021] contains address mapping information which can
be integrated with physical topology information. The physical ports
identified in a physical topology MIB can be related to the MAC and
network layer addresses found in the addressMapTable.

7.5.  Relationship to Bridge MIB

The Bridge MIB [RFC1493] contains information which may relate to
physical ports represented in the ptopoConnTable.  Entries in the
dot1dBasePortTable and dot1dStpPortTable can by related to physical
ports represented in the PTOPO MIB.  Also, bridge port MAC addresses may
be used as chassis and port identifiers in some situations.

7.6.  Relationship to Repeater MIB

The Repeater MIB [RFC2108] contains information which may relate to
physical ports represented in the PTOPO MIB.  Entries in the
rptrPortTable and rptrMonitorPortTable can by related to physical ports
represented in the ptopoConnTable.  Entries in the rptrInfoTable and
rptrMonTable can be related to repeater backplanes possibly represented
in the ptopoConnTable.

7.7.  MIB Structure

The PTOPO MIB contains three MIB object groups:

  - ptopoData
     Exposes physical topology data learned from discovery protocols
     and/or manual configuration.

  - ptopoGeneral
     Contains general information regarding PTOPO MIB status.

  - ptopoConfig
     Contains configuration variables for the PTOPO MIB agent function.

7.7.1.  ptopoData Group

This group contains a single table to identity physical topology data.

The ptopoConnTable contains information about the connections learned or





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configured on behalf of the PTOPO MIB SNMP Agent.

7.7.2.  ptopoGeneral Group

This group contains some scalar objects to report the status of the
PTOPO MIB information currently known to the SNMP Agent. The global last
change time, and table add and delete counters allow an NMS to set
threshold alarms to trigger PTOPO polling.

7.7.3.  ptopoConfig Group

This group contains tables to configure the behavior of the physical
topology function.  The transmission of ptopoLastChange notifications
can be configured using the ptopoConfigTrapInterval scalar MIB object.

7.8.  Physical Topology MIB Definitions

PTOPO-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, OBJECT-TYPE, NOTIFICATION-TYPE,
    Integer32, Counter32, mib-2
        FROM SNMPv2-SMI
    TEXTUAL-CONVENTION, AutonomousType, RowStatus, TimeStamp, TruthValue
        FROM SNMPv2-TC
    MODULE-COMPLIANCE, OBJECT-GROUP, NOTIFICATION-GROUP
        FROM SNMPv2-CONF
    TimeFilter
        FROM RMON2-MIB
    PhysicalIndex
        FROM ENTITY-MIB
    AddressFamilyNumbers
        FROM IANA-ADDRESS-FAMILY-NUMBERS-MIB;

ptopoMIB MODULE-IDENTITY
    LAST-UPDATED "200002110000Z"
    ORGANIZATION "IETF; PTOPOMIB Working Group"
    CONTACT-INFO
       "PTOPOMIB WG Discussion:
        ptopo@3com.com
        Subscription:
        majordomo@3com.com
          msg body: [un]subscribe ptopomib

        Andy Bierman





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        Cisco Systems Inc.
        170 West Tasman Drive
        San Jose, CA 95134
        408-527-3711
        abierman@cisco.com

        Kendall S. Jones
        Nortel Networks
        4401 Great America Parkway
        Santa Clara, CA 95054
        408-495-7356
        kejones@nortelnetworks.com"
    DESCRIPTION
            "The MIB module for physical topology information."
    REVISION        "200002110000Z"
    DESCRIPTION
            "Initial Version of the Physical Topology MIB.  This version
            published as RFC xxxx (to be assigned by the RFC Editor)."
    ::= { mib-2 xx }

ptopoMIBObjects   OBJECT IDENTIFIER ::= { ptopoMIB 1 }


-- MIB groups
ptopoData         OBJECT IDENTIFIER ::= { ptopoMIBObjects 1 }
ptopoGeneral      OBJECT IDENTIFIER ::= { ptopoMIBObjects 2 }
ptopoConfig       OBJECT IDENTIFIER ::= { ptopoMIBObjects 3 }

-- textual conventions


PtopoGenAddr ::= TEXTUAL-CONVENTION
    STATUS      current
    DESCRIPTION
            "The value of an address."
    SYNTAX      OCTET STRING (SIZE (0..20))

PtopoChassisIdType ::= TEXTUAL-CONVENTION
    STATUS      current
    DESCRIPTION
            "This TC describes the source of a chassis identifier.

            The enumeration 'chasIdEntPhysicalAlias(1)' represents a
            chassis identifier based on the value of entPhysicalAlias
            for a chassis component (i.e., an entPhysicalClass value of





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            'chassis(3)').

            The enumeration 'chasIdIfAlias(2)' represents a chassis
            identifier based on the value of ifAlias for an interface on
            the containing chassis.

            The enumeration 'chasIdPortEntPhysicalAlias(3)' represents a
            chassis identifier based on the value of entPhysicalAlias
            for a port or backplane component (i.e., entPhysicalClass
            value of 'port(10)' or 'backplane(4)'), within the
            containing chassis.

            The enumeration 'chasIdMacAddress(4)' represents a chassis
            identifier based on the value of a unicast source MAC
            address (encoded in network byte order and IEEE 802.3
            canonical bit order), of a port on the containing chassis.

            The enumeration 'chasIdPtopoGenAddr(5)' represents a chassis
            identifier based on a network address, associated with a
            particular chassis.  The encoded address is actually
            composed of two fields.  The first field is a single octet,
            representing the IANA AddressFamilyNumbers value for the
            specific address type, and the second field is the
            PtopoGenAddr address value."
    SYNTAX      INTEGER {
            chasIdEntPhysicalAlias(1),
            chasIdIfAlias(2),
            chasIdPortEntPhysicalAlias(3),
            chasIdMacAddress(4),
            chasIdPtopoGenAddr(5)
    }

PtopoChassisId ::= TEXTUAL-CONVENTION
    STATUS      current
    DESCRIPTION
            "This TC describes the format of a chassis identifier
            string.  Objects of this type are always used with an
            associated PtopoChassisIdType object, which identifies the
            format of the particular PtopoChassisId object instance.

            If the associated PtopoChassisIdType object has a value of
            'chasIdEntPhysicalAlias(1)', then the octet string
            identifies a particular instance of the entPhysicalAlias
            object for a chassis component (i.e., an entPhysicalClass
            value of 'chassis(3)').





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            If the associated PtopoChassisIdType object has a value of
            'chasIdIfAlias(2)', then the octet string identifies a
            particular instance of the ifAlias object for an interface
            on the containing chassis.

            If the associated PtopoChassisIdType object has a value of
            'chasIdPortEntPhysicalAlias(3)', then the octet string
            identifies a particular instance of the entPhysicalAlias
            object for a port or backplane component within the
            containing chassis.

            If the associated PtopoChassisIdType object has a value of
            'chasIdMacAddress(4)', then this string identifies a
            particular unicast source MAC address (encoded in network
            byte order and IEEE 802.3 canonical bit order), of a port on
            the containing chassis.

            If the associated PtopoChassisIdType object has a value of
            'chasIdPtopoGenAddr(5)', then this string identifies a
            particular network address, encoded in network byte order,
            associated with one or more ports on the containing chassis.
            The first octet contains the IANA Address Family Numbers
            enumeration value for the specific address type, and octets
            2 through N contain the PtopoGenAddr address value in
            network byte order."
    SYNTAX      OCTET STRING (SIZE (1..32))

PtopoPortIdType ::= TEXTUAL-CONVENTION
    STATUS      current
    DESCRIPTION
            "This TC describes the source of a particular type of port
            identifier used in the PTOPO MIB.

            The enumeration 'portIdIfAlias(1)' represents a port
            identifier based on the ifAlias MIB object.

            The enumeration 'portIdPortEntPhysicalAlias(2)' represents a
            port identifier based on the value of entPhysicalAlias for a
            port or backplane component (i.e., entPhysicalClass value of
            'port(10)' or 'backplane(4)'), within the containing
            chassis.

            The enumeration 'portIdMacAddr(3)' represents a port
            identifier based on a unicast source MAC address, which has
            been detected by the agent and associated with a particular





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            port.

            The enumeration 'portIdPtopoGenAddr(4)' represents a port
            identifier based on a network address, detected by the agent
            and associated with a particular port."
    SYNTAX      INTEGER {
            portIdIfAlias(1),
            portIdEntPhysicalAlias(2),
            portIdMacAddr(3),
            portIdPtopoGenAddr(4)
    }

PtopoPortId ::= TEXTUAL-CONVENTION
    STATUS      current
    DESCRIPTION
            "This TC describes the format of a port identifier string.
            Objects of this type are always used with an associated
            PtopoPortIdType object, which identifies the format of the
            particular PtopoPortId object instance.

            If the associated PtopoPortIdType object has a value of
            'portIdIfAlias(1)', then the octet string identifies a
            particular instance of the ifAlias object.

            If the associated PtopoPortIdType object has a value of
            'portIdEntPhysicalAlias(2)', then the octet string
            identifies a particular instance of the entPhysicalAlias
            object for a port component (i.e., entPhysicalClass value of
            'port(10)').

            If the associated PtopoPortIdType object has a value of
            'portIdMacAddr(3)', then this string identifies a particular
            unicast source MAC address associated with the port.

            If the associated PtopoPortIdType object has a value of
            'portIdPtopoGenAddr(4)', then this string identifies a
            network address associated with the port.  The first octet
            contains the IANA AddressFamilyNumbers enumeration value for
            the specific address type, and octets 2 through N contain
            the PtopoGenAddr address value in network byte order."
    SYNTAX      OCTET STRING (SIZE (1..32))


PtopoAddrSeenState ::= TEXTUAL-CONVENTION
    STATUS      current





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    DESCRIPTION
            "This TC describes the state of address detection for a
            particular type of port identifier used in the PTOPO MIB.

            The enumeration 'notUsed(1)' represents an entry for which
            the particular MIB object is not applicable to the remote
            connection endpoint,

            The enumeration 'unknown(2)' represents an entry for which
            the particular address collection state is not known.

            The enumeration 'oneAddr(3)'  represents an entry for which
            exactly one source address (of the type indicated by the
            particular MIB object), has been detected.

            The enumeration 'multiAddr(4)'  represents an entry for
            which more than one source address (of the type indicated by
            the particular MIB object), has been detected.

            An agent is expected to set the initial state of the
            PtopoAddrSeenState to 'notUsed(1)' or 'unknown(2)'.

            Note that the PTOPO MIB does not restrict or specify the
            means in which the PtopoAddrSeenState is known to an agent.
            In particular, an agent may detect this information through
            configuration data, or some means other than directly
            monitoring all port traffic."
    SYNTAX      INTEGER {
            notUsed(1),
            unknown(2),
            oneAddr(3),
            multiAddr(4)
    }

--  ***********************************************************
--
--           P T O P O    D A T A     G R O U P
--
--  ***********************************************************

-- Connection Table

ptopoConnTable OBJECT-TYPE
    SYNTAX      SEQUENCE OF PtopoConnEntry
    MAX-ACCESS  not-accessible





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    STATUS      current
    DESCRIPTION
            "This table contains one or more rows per physical network
            connection known to this agent.  The agent may wish to
            ensure that only one ptopoConnEntry is present for each
            local port, or it may choose to maintain multiple
            ptopoConnEntries for the same local port.

            Entries based on lower numbered identifier types are
            preferred over higher numbered identifier types, i.e., lower
            values of the ptopoConnRemoteChassisType and
            ptopoConnRemotePortType objects."
    ::= { ptopoData 1 }

ptopoConnEntry       OBJECT-TYPE
    SYNTAX      PtopoConnEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "Information about a particular physical network connection.
            Entries may be created and deleted in this table, either
            manually or by the agent, if a physical topology discovery
            process is active."
    INDEX   {
           ptopoConnTimeMark,
           ptopoConnLocalChassis,
           ptopoConnLocalPort,
           ptopoConnIndex
    }
    ::= { ptopoConnTable 1 }

PtopoConnEntry ::= SEQUENCE {
      ptopoConnTimeMark            TimeFilter,
      ptopoConnLocalChassis        PhysicalIndex,
      ptopoConnLocalPort           PhysicalIndex,
      ptopoConnIndex               Integer32,
      ptopoConnRemoteChassisType   PtopoChassisIdType,
      ptopoConnRemoteChassis       PtopoChassisId,
      ptopoConnRemotePortType      PtopoPortIdType,
      ptopoConnRemotePort          PtopoPortId,
      ptopoConnDiscAlgorithm       AutonomousType,
      ptopoConnAgentNetAddrType    AddressFamilyNumbers,
      ptopoConnAgentNetAddr        PtopoGenAddr,
      ptopoConnMultiMacSASeen      PtopoAddrSeenState,
      ptopoConnMultiNetSASeen      PtopoAddrSeenState,





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      ptopoConnIsStatic            TruthValue,
      ptopoConnLastVerifyTime      TimeStamp,
      ptopoConnRowStatus           RowStatus
}

ptopoConnTimeMark  OBJECT-TYPE
    SYNTAX      TimeFilter
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "A TimeFilter for this entry.  See the TimeFilter textual
            convention in RFC 2021 to see how this works."
    ::= { ptopoConnEntry 1 }

ptopoConnLocalChassis  OBJECT-TYPE
    SYNTAX      PhysicalIndex
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "The entPhysicalIndex value used to identify the chassis
            component associated with the local connection endpoint."
    ::= { ptopoConnEntry 2 }

ptopoConnLocalPort     OBJECT-TYPE
    SYNTAX      PhysicalIndex
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "The entPhysicalIndex value used to identify the port
            component associated with the local connection endpoint."
    ::= { ptopoConnEntry 3 }

ptopoConnIndex    OBJECT-TYPE
    SYNTAX      Integer32  (1..2147483647)
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "This object represents an arbitrary local integer value
            used by this agent to identify a particular connection
            instance, unique only for the indicated local connection
            endpoint.

            A particular ptopoConnIndex value may be reused in the event
            an entry is aged out and later re-learned with the same (or
            different) remote chassis and port identifiers.





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            An agent is encouraged to assign monotonically increasing
            index values to new entries, starting with one, after each
            reboot.  It is considered unlikely that the ptopoConnIndex
            will wrap between reboots."
    ::= { ptopoConnEntry 4 }

ptopoConnRemoteChassisType  OBJECT-TYPE
    SYNTAX      PtopoChassisIdType
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The type of encoding used to identify the chassis
            associated with the remote connection endpoint.

            This object may not be modified if the associated
            ptopoConnRowStatus object has a value of active(1)."
    ::= { ptopoConnEntry 5 }

ptopoConnRemoteChassis  OBJECT-TYPE
    SYNTAX      PtopoChassisId
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The string value used to identify the chassis component
            associated with the remote connection endpoint.

            This object may not be modified if the associated
            ptopoConnRowStatus object has a value of active(1)."
    ::= { ptopoConnEntry 6 }

ptopoConnRemotePortType  OBJECT-TYPE
    SYNTAX      PtopoPortIdType
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The type of port identifier encoding used in the associated
            'ptopoConnRemotePort' object.

            This object may not be modified if the associated
            ptopoConnRowStatus object has a value of active(1)."
    ::= { ptopoConnEntry 7 }

ptopoConnRemotePort  OBJECT-TYPE
    SYNTAX      PtopoPortId
    MAX-ACCESS  read-create





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    STATUS      current
    DESCRIPTION
            "The string value used to identify the port component
            associated with the remote connection endpoint.

            This object may not be modified if the associated
            ptopoConnRowStatus object has a value of active(1)."
    ::= { ptopoConnEntry 8 }

ptopoConnDiscAlgorithm OBJECT-TYPE
    SYNTAX      AutonomousType
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "An indication of the algorithm used to discover the
            information contained in this conceptual row.


            A value of ptopoDiscoveryLocal indicates this entry was
            configured by the local agent, without use of a discovery
            protocol.

            A value of { 0 0 } indicates this entry was created manually
            by an NMS via the associated RowStatus object. "
    ::= { ptopoConnEntry 9 }

ptopoConnAgentNetAddrType  OBJECT-TYPE
    SYNTAX      AddressFamilyNumbers
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "This network address type of the associated
            ptopoConnNetAddr object, unless that object contains a zero
            length string.  In such a case, an NMS application should
            ignore any returned value for this object.

            This object may not be modified if the associated
            ptopoConnRowStatus object has a value of active(1)."
    ::= { ptopoConnEntry 10 }

ptopoConnAgentNetAddr  OBJECT-TYPE
    SYNTAX      PtopoGenAddr
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION





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            "This object identifies a network address which may be used
            to reach an SNMP agent entity containing information for the
            chassis and port components represented by the associated
            'ptopoConnRemoteChassis' and 'ptopoConnRemotePort' objects.
            If no such address is known, then this object shall contain
            an empty string.

            This object may not be modified if the associated
            ptopoConnRowStatus object has a value of active(1)."
    ::= { ptopoConnEntry 11 }

ptopoConnMultiMacSASeen  OBJECT-TYPE
    SYNTAX      PtopoAddrSeenState
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "This object indicates if multiple unicast source MAC
            addresses have been detected by the agent from the remote
            connection endpoint, since the creation of this entry.

            If this entry has an associated ptopoConnRemoteChassisType
            and/or ptopoConnRemotePortType value other than
            'portIdMacAddr(3)', then the value 'notUsed(1)' is returned.

            Otherwise, one of the following conditions must be true:

            If the agent has not yet detected any unicast source MAC
            addresses from the remote port, then the value 'unknown(2)'
            is returned.

            If the agent has detected exactly one unicast source MAC
            address from the remote port, then the value 'oneAddr(3)' is
            returned.

            If the agent has detected more than one unicast source MAC
            address from the remote port, then the value 'multiAddr(4)'
            is returned."
    ::= { ptopoConnEntry 12 }

ptopoConnMultiNetSASeen  OBJECT-TYPE
    SYNTAX      PtopoAddrSeenState
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "This object indicates if multiple network layer source





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            addresses have been detected by the agent from the remote
            connection endpoint, since the creation of this entry.

            If this entry has an associated ptopoConnRemoteChassisType
            or ptopoConnRemotePortType value other than
            'portIdGenAddr(4)' then the value 'notUsed(1)' is returned.

            Otherwise, one of the following conditions must be true:

            If the agent has not yet detected any network source
            addresses of the appropriate type from the remote port, then
            the value 'unknown(2)' is returned.

            If the agent has detected exactly one network source address
            of the appropriate type from the remote port, then the value
            'oneAddr(3)' is returned.

            If the agent has detected more than one network source
            address (of the same appropriate type) from the remote port,
            this the value 'multiAddr(4)' is returned."
    ::= { ptopoConnEntry 13 }

ptopoConnIsStatic  OBJECT-TYPE
    SYNTAX      TruthValue
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "This object identifies static ptopoConnEntries.  If this
            object has the value 'true(1)', then this entry is not
            subject to any age-out mechanisms implemented by the agent.

            If this object has the value 'false(2)', then this entry is
            subject to all age-out mechanisms implemented by the agent.

            This object may not be modified if the associated
            ptopoConnRowStatus object has a value of active(1)."
    DEFVAL { false }
    ::= { ptopoConnEntry 14 }

ptopoConnLastVerifyTime  OBJECT-TYPE
    SYNTAX      TimeStamp
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "If the associated value of ptopoConnIsStatic is equal to





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            'false(2)', then this object contains the value of sysUpTime
            at the time the conceptual row was last verified by the
            agent, e.g., via reception of a topology protocol message,
            pertaining to the associated remote chassis and port.

            If the associated value of ptopoConnIsStatic is equal to
            'true(1)', then this object shall contain the value of
            sysUpTime at the time this entry was last activated (i.e.,
            ptopoConnRowStatus set to 'active(1)')."
    ::= { ptopoConnEntry 15 }

ptopoConnRowStatus OBJECT-TYPE
    SYNTAX      RowStatus
    MAX-ACCESS  read-create
    STATUS      current
    DESCRIPTION
            "The status of this conceptual row."
    ::= { ptopoConnEntry 16 }

--  ***********************************************************
--
--           P T O P O    G E N E R A L     G R O U P
--
--  ***********************************************************

-- last change time stamp for the whole MIB

ptopoLastChangeTime OBJECT-TYPE
    SYNTAX      TimeStamp
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The value of sysUpTime at the time a conceptual row is
            created, modified, or deleted in the ptopoConnTable.

            An NMS can use this object to reduce polling of the
            ptopoData group objects."
    ::= { ptopoGeneral 1 }

ptopoConnTabInserts OBJECT-TYPE
    SYNTAX      Counter32
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The number of times an entry has been inserted into the





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            ptopoConnTable."
    ::= { ptopoGeneral 2 }

ptopoConnTabDeletes OBJECT-TYPE
    SYNTAX      Counter32
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The number of times an entry has been deleted from the
            ptopoConnTable."
    ::= { ptopoGeneral 3 }

ptopoConnTabDrops OBJECT-TYPE
    SYNTAX      Counter32
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The number of times an entry would have been added to the
            ptopoConnTable, (e.g., via information learned from a
            topology protocol), but was not because of insufficient
            resources."
    ::= { ptopoGeneral 4 }

ptopoConnTabAgeouts OBJECT-TYPE
    SYNTAX      Counter32
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The number of times an entry has been deleted from the
            ptopoConnTable because the information timeliness interval
            for that entry has expired."
    ::= { ptopoGeneral 5 }

--  ***********************************************************
--
--           P T O P O    C O N F I G     G R O U P
--
--  ***********************************************************

ptopoConfigTrapInterval OBJECT-TYPE
    SYNTAX      Integer32 (0 | 5..3600)
    UNITS       "seconds"
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION





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            "This object controls the transmission of PTOPO
            notifications.

            If this object has a value of zero, then no
            ptopoConfigChange notifications will be transmitted by the
            agent.

            If this object has a non-zero value, then the agent must not
            generate more than one ptopoConfigChange trap-event in the
            indicated period, where a 'trap-event' is the transmission
            of a single notification PDU type to a list of notification
            destinations.  If additional configuration changes occur
            within the indicated throttling period, then these trap-
            events must be suppressed by the agent. An NMS should
            periodically check the value of ptopoLastChangeTime to
            detect any missed ptopoConfigChange trap-events, e.g. due to
            throttling or transmission loss.

            If notification transmission is enabled, the suggested
            default throttling period is 60 seconds, but transmission
            should be disabled by default.

            If the agent is capable of storing non-volatile
            configuration, then the value of this object must be
            restored after a re-initialization of the management
            system."
    DEFVAL { 0 }
    ::= { ptopoConfig 1 }

ptopoConfigMaxHoldTime OBJECT-TYPE
    SYNTAX      Integer32 (1..2147483647)
    UNITS       "seconds"
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "This object specifies the desired time interval for which
            an agent will maintain dynamic ptopoConnEntries.

            After the specified number of seconds since the last time an
            entry was verified, in the absence of new verification
            (e.g., receipt of a topology protocol message), the agent
            shall remove the entry.  Note that entries may not always be
            removed immediately, but may possibly be removed at periodic
            garbage collection intervals.






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            This object only affects dynamic ptopoConnEntries, i.e.  for
            which ptopoConnIsStatic equals 'false(2)'. Static entries
            are not aged out.

            Note that dynamic ptopoConnEntries may also be removed by
            the agent due to the expired timeliness of learned topology
            information (e.g., timeliness interval for a remote port
            expires).  The actual age-out interval for a given entry is
            defined by the following formula:

              age-out-time =
                min(ptopoConfigMaxHoldTime, <entry-specific hold-time>)

            where <entry-specific hold-time> is determined by the
            discovery algorithm, and may be different for each entry."
    DEFVAL { 300 }
    ::= { ptopoConfig 2 }


-- PTOPO MIB Notification Definitions
ptopoMIBNotifications  OBJECT IDENTIFIER ::= { ptopoMIB 2 }
ptopoMIBTrapPrefix     OBJECT IDENTIFIER ::=
      { ptopoMIBNotifications 0 }

ptopoConfigChange NOTIFICATION-TYPE
    OBJECTS       {
             ptopoConnTabInserts,
             ptopoConnTabDeletes,
             ptopoConnTabDrops,
             ptopoConnTabAgeouts
    }
    STATUS        current
    DESCRIPTION
            "A ptopoConfigChange notification is sent when the value of
            ptopoLastChangeTime changes. It can be utilized by an NMS to
            trigger physical topology table maintenance polls.

            Note that transmission of ptopoConfigChange notifications
            are throttled by the agent, as specified by the
            'ptopoConfigTrapInterval' object."
   ::= { ptopoMIBTrapPrefix 1 }


-- PTOPO Registration Points
ptopoRegistrationPoints  OBJECT IDENTIFIER ::= { ptopoMIB 3 }





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-- values used with ptopoConnDiscAlgorithm object
ptopoDiscoveryMechanisms OBJECT IDENTIFIER ::=
      { ptopoRegistrationPoints 1 }

ptopoDiscoveryLocal      OBJECT IDENTIFIER ::=
      { ptopoDiscoveryMechanisms 1 }


-- conformance information
ptopoConformance OBJECT IDENTIFIER ::= { ptopoMIB 4 }

ptopoCompliances OBJECT IDENTIFIER ::= { ptopoConformance 1 }
ptopoGroups      OBJECT IDENTIFIER ::= { ptopoConformance 2 }

-- compliance statements

ptopoCompliance MODULE-COMPLIANCE
   STATUS  current
    DESCRIPTION
            "The compliance statement for SNMP entities which implement
            the PTOPO MIB."
    MODULE  -- this module
        MANDATORY-GROUPS {
              ptopoDataGroup,
              ptopoGeneralGroup,
              ptopoConfigGroup,
              ptopoNotificationsGroup
        }
    ::= { ptopoCompliances 1 }

-- MIB groupings

ptopoDataGroup   OBJECT-GROUP
    OBJECTS {
         ptopoConnRemoteChassisType,
         ptopoConnRemoteChassis,
         ptopoConnRemotePortType,
         ptopoConnRemotePort,
         ptopoConnDiscAlgorithm,
         ptopoConnAgentNetAddrType,
         ptopoConnAgentNetAddr,
         ptopoConnMultiMacSASeen,
         ptopoConnMultiNetSASeen,
         ptopoConnIsStatic,
         ptopoConnLastVerifyTime,





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         ptopoConnRowStatus
    }
    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to represent
            physical topology information for which a single agent
            provides management information.

            This group is mandatory for all implementations of the PTOPO
            MIB."
    ::= { ptopoGroups 1 }

ptopoGeneralGroup    OBJECT-GROUP
    OBJECTS {
         ptopoLastChangeTime,
         ptopoConnTabInserts,
         ptopoConnTabDeletes,
         ptopoConnTabDrops,
         ptopoConnTabAgeouts
    }
    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to report the
            general status of the PTOPO MIB implementation.

            This group is mandatory for all agents which implement the
            PTOPO MIB."
    ::= { ptopoGroups 2 }

ptopoConfigGroup    OBJECT-GROUP
    OBJECTS {
         ptopoConfigTrapInterval,
         ptopoConfigMaxHoldTime
    }
    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to configure the
            PTOPO MIB implementation behavior.

            This group is mandatory for agents which implement the PTOPO
            MIB."
    ::= { ptopoGroups 3 }

ptopoNotificationsGroup NOTIFICATION-GROUP
    NOTIFICATIONS {





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         ptopoConfigChange
    }
    STATUS        current
    DESCRIPTION
            "The collection of notifications used to indicate PTOPO MIB
            data consistency and general status information.

            This group is mandatory for agents which implement the PTOPO
            MIB."
    ::= { ptopoGroups 4 }

END






































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8.  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.

The IETF has been notified of intellectual property rights claimed in
regard to some or all of the specification contained in this document.
For more information consult the online list of claimed rights.

























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9.  Acknowledgements

The PTOPO Discovery Protocol is a product of the IETF PTOPOMIB Working
Group.

10.  References

[RFC1155]   Rose, M., and K. McCloghrie, "Structure and Identification
            of Management Information for TCP/IP-based Internets", STD
            16, RFC 1155, May 1990.

[RFC1157]   Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple
            Network Management Protocol", STD 15, RFC 1157, May 1990.

[RFC1212]   Rose, M., and K. McCloghrie, "Concise MIB Definitions", STD
            16, RFC 1212, March 1991.

[RFC1215]   M. Rose, "A Convention for Defining Traps for use with the
            SNMP", RFC 1215, March 1991.

[RFC1493]   Decker, E., Langille, P., Rijsinghani, A., and K.
            McCloghrie, "Definitions of Managed Objects for Bridges",
            RFC 1493, Cisco Systems, Inc., Digital Equipment
            Corporation, Hughes LAN Systems, Inc., July 1993.

[RFC1700]   Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC
            1700, USC/Information Sciences Institute, October 1994.

[RFC1901]   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.

[RFC1902]   SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M.,
            and S. Waldbusser, "Structure of Management Information for
            version 2 of the Simple Network Management Protocol
            (SNMPv2)", RFC 1902, SNMP Research, Inc., Cisco Systems,
            Inc., Dover Beach Consulting, Inc.,  International Network
            Services, January 1996.

[RFC1903]   SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M.,
            and S. Waldbusser, "Textual Conventions for version 2 of the
            Simple Network Management Protocol (SNMPv2)", RFC 1903, SNMP
            Research, Inc., Cisco Systems, Inc., Dover Beach Consulting,





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            Inc.,  International Network Services, January 1996.

[RFC1904]   SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M.,
            and S. Waldbusser, "Conformance Statements for version 2 of
            the Simple Network Management Protocol (SNMPv2)", RFC 1904,
            SNMP Research, Inc., Cisco Systems, Inc., Dover Beach
            Consulting, Inc.,  International Network Services, January
            1996.

[RFC1905]   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.

[RFC1906]   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.

[RFC2021]   S. Waldbusser, "Remote Network Monitoring MIB (RMON-2)", RFC
            2021, International Network Services, January 1997.

[RFC2037]   McCloghrie, K., and A. Bierman, "Entity MIB using SMIv2",
            RFC 2037, Cisco Systems, October 1996.

[RFC2108]   de Graaf, K., Romascanu, D., McMaster, D., and K.
            McCloghrie, "Definitions of Managed Objects for IEEE 802.3
            Repeater Devices using SMIv2", RFC 2108, 3Com Corporation,
            Madge Networks (Israel) Ltd., Coloma Communications, Cisco
            Systems Inc., February 1997.

[RFC2233]   McCloghrie, K., and F. Kastenholtz, "The Interfaces Group
            MIB using SMIv2", RFC 2233, Cisco Systems, FTP Software,
            November 1997.

[RFC2570]   Case, J., Mundy, R., Partain, D., and B. Stewart,
            "Introduction to Version 3 of the Internet-standard Network
            Management Framework", RFC 2570, April 1999.

[RFC2571]   Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture
            for Describing SNMP Management Frameworks", RFC 2571, April
            1999.





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[RFC2572]   Case, J., Harrington D., Presuhn R., and B. Wijnen, "Message
            Processing and Dispatching for the Simple Network Management
            Protocol (SNMP)", RFC 2572, April 1999.

[RFC2573]   Levi, D., Meyer, P., and B. Stewart, "SNMPv3 Applications",
            RFC 2573, April 1999.

[RFC2574]   Blumenthal, U., and B. Wijnen, "User-based Security Model
            (USM) for version 3 of the Simple Network Management
            Protocol (SNMPv3)", RFC 2574, April 1999.

[RFC2575]   Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based
            Access Control Model (VACM) for the Simple Network
            Management Protocol (SNMP)", RFC 2575, April 1999.

[RFC2578]   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.

[RFC2579]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
            Rose, M., and S. Waldbusser, "Textual Conventions for
            SMIv2", STD 58, RFC 2579, April 1999.

[RFC2580]   McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
            Rose, M., and S. Waldbusser, "Conformance Statements for
            SMIv2", STD 58, RFC 2580, April 1999.

[RFC2737]   McCloghrie, K., and A. Bierman, "Entity MIB (Version 2)",
            RFC 2737, Cisco Systems, December 1999.

11.  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.

There are a number of managed objects in this MIB that may contain
sensitive information. These are:

   read-create objects:
      ptopoConnRemoteChassisType
      ptopoConnRemoteChassis





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      ptopoConnRemotePortType
      ptopoConnRemotePort
      ptopoConnAgentNetAddrType
      ptopoConnAgentNetAddr
      ptopoConnIsStatic
      ptopoConfigTrapInterval
      ptopoConfigMaxHoldTime

   read-only objects:
      ptopoConnDiscAlgorithm
      ptopoConnMultiMacSASeen
      ptopoConnMultiNetSASeen
      ptopoConnLastVerifyTime
      ptopoLastChangeTime

   notifications:
      ptopoConfigChange


These MIB objects expose information about the physical connectivity for
a particular portion of a network.

A network administrator may also wish to inhibit transmission of any
ptopoConfigChange notification by setting the ptopoConfigTrapInterval
object to zero.

It is thus important to control even GET access to these objects and
possibly to even encrypt the values of these object when sending them
over the network via SNMP.  Not all versions of SNMP provide features
for such a secure environment.

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 [RFC2574] and the View- based Access
Control Model RFC 2575 [RFC2575] 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.





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12.  Authors' Addresses

     Andy Bierman
     Cisco Systems
     170 West Tasman Drive
     San Jose, CA USA 95134
     Phone: +1 408-527-3711
     Email: abierman@cisco.com

     Kendall S. Jones
     Nortel Networks
     4401 Great America Parkway
     Santa Clara, CA USA 95054
     Phone: +1 408-495-7356
     Email: kejones@nortelnetworks.com



































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13.  Full Copyright Statement

Copyright (C) The Internet Society (2000).  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 implementation 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
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."
























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