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Versions: 00 01 02 03                                                   
Draft               PTOPO Discovery Protocol and MIB          March 1998


                    <draft-ietf-ptopomib-pdp-02.txt>
              Physical Topology Discovery Protocol and MIB


                              2 March 1998


                              Andy Bierman
                           Cisco Systems Inc.
                           abierman@cisco.com


                            Keith McCloghrie
                           Cisco Systems Inc.
                             kzm@cisco.com





                          Status of this Memo


This document is an Internet-Draft.  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.''

To learn the current status of any Internet-Draft, please check the
``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow
Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe),
ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).


1.  Introduction

This memo defines an experimental protocol, and an experimental portion
of the Management Information Base (MIB) for use with network management
protocols in the Internet community.  In particular, it describes a
physical topology discovery protocol and managed objects used for





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managing the protocol.


2.  The SNMP Network Management Framework

The SNMP Network Management Framework presently consists of three major
components.  They are:

o    the SMI, described in RFC 1902 [RFC1902], - the mechanisms used for
     describing and naming objects for the purpose of management.

o    the MIB-II, STD 17, RFC 1213 [RFC1213], - the core set of managed
     objects for the Internet suite of protocols.

o    the protocol, RFC 1157 [RFC1157] and/or RFC 1905 [RFC1905], - the
     protocol for accessing managed information.

Textual conventions are defined in RFC 1903 [RFC1903], and conformance
statements are defined in RFC 1904 [RFC1904].

The Framework permits new objects to be defined for the purpose of
experimentation and evaluation.

This memo specifies a MIB module that is compliant to the SNMPv2 SMI.  A
semantically identical MIB conforming to the SNMPv1 SMI can be produced
through the appropriate translation.


2.1.  Object Definitions

Managed objects are accessed via a virtual information store, termed the
Management Information Base or MIB.  Objects in the MIB are defined
using the subset of Abstract Syntax Notation One (ASN.1) defined in the
SMI.  In particular, each object type is named by an OBJECT IDENTIFIER,
an administratively assigned name.  The object type together with an
object instance serves to uniquely identify a specific instantiation of
the object.  For human convenience, we often use a textual string,
termed the descriptor, to refer to the object type.


3.  Overview

There is a need for a standardized way of representing the physical
network connections pertaining to a given management domain.  A
standardized discovery mechanism is also required to increase the





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likelihood of multi-vendor interoperability of such physical topology
management information.

This document specifies a discovery protocol, suitable for use with the
Physical Topology MIB [PTOPO].


3.1.  Terms

Some terms are used throughout this document:

SNMP Agent
     This term refers to an SNMP agent co-located with a particular PDP
     Agent. Specifically, it refers to the SNMP Agent providing PDP MIB,
     Entity MIB, Interfaces MIB, and possibly PTOPO MIB support for a
     particular chassis.

PDP Agent
     This term refers to a software entity which implements the PTOPO
     Discovery Protocol for a particular chassis.


3.2.  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 or Interfaces MIB can be
used as the 'reference-point' for a connection component identifier.


3.3.  Relationship to the Physical Topology MIB

The Physical Topology MIB [PTOPO] allows a PDP Agent to expose learned
physical topology information, using a standard MIB.  PDP is intended to
fully support the PTOPO MIB.


3.4.  Relationship to Entity MIB

The Entity MIB [RFC2037] allows the physical component inventory and
hierarchy to be identified.  The chassis identifier strings passed in
PDP messages identify entPhysicalTable entries, and implementation of





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the entPhysicalTable and entPhysicalXTable (found in 'Entity MIB
Extensions for Persistent Component Identification' [ENTITY-EXT]) are
required for SNMP agents which also implement the PDP MIB.


3.5.  Relationship to Interfaces MIB

The Interfaces MIB provides a standard mechanism for managing network
interfaces. The port identifier strings passed in PDP messages identify
ifTable (or entPhysicalTable) entries, and implementation of the ifTable
and ifXTable [RFC2233] are required for SNMP agents which also implement
the PDP MIB, for the ports which are represented in the Interfaces MIB.


4.  PTOPO Discovery Protocol

This section defines a discovery protocol, suitable for supporting the
data requirements of the PTOPO MIB.

The PTOPO Discovery Protocol (PDP) is a media independent protocol
intended to be run on routers, bridges, access servers, switches,
repeaters, etc., allowing a PDP agent to learn SNMP reachability and
connection endpoint information from adjacent devices.

PDP runs on various media that support Subnetwork Access Protocol
(SNAP), and runs over the data-link layer only, allowing two systems
running different network layer protocols can learn about each other.

Each device configured with an active PDP Agent sends periodic messages
to a multicast MAC address on all physical interfaces enabled for PDP
transmission, and listens for PDP messages on the same set on
interfaces. Each PDP message contains information identifying the source
port as a PTOPO connection endpoint identifier. It also contains at
least one network address which can be used by an NMS to reach an SNMP
agent on the device (via the indicated source port).  Each PDP message
contains a configurable time-to-live value, which tells the recipient
PDP agent when to discard each element of learned topology information.


4.1.  Frame Encapsulation

The following open issues are under consideration by the working group:

     An EtherType value must be selected to identify PDP messages
     transmitted over DIX Ethernet, and IEEE 802.3,802.5 media types





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     (using LLC/SNAP encapsulation).

     A multicast MAC address must be selected for the destination
     address (DA) field in PDP messages transmitted over DIX Ethernet,
     IEEE 802.3, and IEEE 802.5 media types.


4.2.  PDP Forwarding

If at all possible, PDP agents are not supposed to forward PDP messages
received on any port.   However, some devices, such as repeaters, cannot
examine each frame received on an interface or port.  Such a device will
allow PDP messages to be retransmitted on one or more local ports, and
will transmit its own PDP messages on those ports as well.  These agents
are termed 'forwarding' PDP agents.

PDP agents located on devices which examine each frame before
retransmitting it (e.g., routers and bridges), are expected to process
received PDP messages and not retransmit them on any local port. These
agents are termed 'non-forwarding' PDP agents.

An NMS may find physical topology information about the same physical
port, represented by several PTOPO agents.  This may occur for one of
several reasons, including a mixture of forwarding and non-forwarding
PDP agents within a network.


4.3.  PDP Message Format

The basic PDP packet consists of a header, followed by a variable number
of variable bindings in an ASN.1/BER encoded 'VarBindList', as indicated
in Figure 1.

         +------------+--------------------------------------+
         |   header   |        (ASN.1/BER) VarBindList       |
         +------------+--------------------------------------+

                [ Figure 1 -- Basic PDP Message Format ]


4.3.1.  PDP Header Format

The PDP header is a 4 byte header, in network byte order,
 containing 3 fields, as shown in figure 2:






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          0                   1                   2                   3
          0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |      Version  |     Flags     |         Time To Live          |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        [ figure 2 -- PDP Message Format ]

The PDP header contains the following fields:

   - Version
     The PDP protocol version number, set to 0x01 for this version of
     the protocol.

   - Flags
     The PDP flags field provide for future header extensions and keep
     the header word-aligned for easier processing. No flag definition
     bits are defined at this time. This field must be set to zero in
     all version 1 PDP messages.

   - Time to live
     The number of seconds the information in this PDP message should be
     regarded as valid by the recipient. Agents of the PTOPO MIB must
     not return MIB information based on expired PDP messages.  The
     valid range is 0 to 65535 for this field.


4.3.2.  PDP PDU Encoding

Following the PDP header is an SNMP varbind list encoded in ASN.1/BER
[ref. TBD], also referred to as the PDP protocol data unit (PDP-PDU).
The individual MIB instances contained in a PDP PDU are referred to as
PDP data elements.

The standard PDP data elements, defined in the PDP Data MIB, are encoded
as a VarBindList in each PDP message.  This data enables a PDP agent to
implement the PTOPO MIB for connections terminating on the local
chassis.

This section defines the ASN.1 syntax specific to the PDP message.
Refer to the Protocol Operations specification [RFC1905] for a complete
definition of the 'VarBindList' construct.

Note that PDP places no constraints on which MIB instances may be
included in a particular VarBindList.





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PDP-PDU DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY
        FROM SNMPv2-SMI
    VarBindList
        FROM SNMPv2-PDU;

PDPv1-PDU MODULE-IDENTITY
    LAST-UPDATED "9709150000Z"
    ORGANIZATION "IETF PTOPOMIB Working Group"
    CONTACT-INFO
       "PTOPOMIB WG Discussion:
        ptopo@3com.com
        Subscription:
        majordomo@3com.com
          msg body: [un]subscribe ptopomib

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

        Keith McCloghrie
        Cisco Systems Inc.
        170 West Tasman Drive
        San Jose, CA 95134
        408-526-5260
        kzm@cisco.com"
    DESCRIPTION
            "The definition module for version 1 of the PTOPO Discovery
            Protocol PDU syntax."
    ::= { experimental xx }

PDP-PDU ::=
    SEQUENCE {
        pdp-variable-bindings
            VarBindList
    }

END







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4.4.  PDP Data MIB

This section defines the standard data elements which may be contained
in PDP messages.  These elements are defined as MIB objects, but are
only intended to be encoded into PDP PDUs, and not intended to be
instrumented by an SNMP agent.

The MIB defines six standard data elements:

    - Chassis ID
    - Chassis ID Type
    - Port ID
    - Port ID Type
    - Management Address Type
    - Management Address


4.4.1.  Definitions

PDP-DATA-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, OBJECT-TYPE, Integer32
        FROM SNMPv2-SMI
    MODULE-COMPLIANCE, OBJECT-GROUP
        FROM SNMPv2-CONF
    IANAAddrFamily, PtopoGenAddr, PtopoChassisIdType,
    PtopoChassisId, PtopoPortIdType, PtopoPortId
        FROM PTOPO-MIB;


pdpDataMIB MODULE-IDENTITY
    LAST-UPDATED "9709150000Z"
    ORGANIZATION "IETF PTOPOMIB Working Group"
    CONTACT-INFO
       "PTOPOMIB WG Discussion:
        ptopo@3com.com
        Subscription:
        majordomo@3com.com
          msg body: [un]subscribe ptopomib

        Andy Bierman
        Cisco Systems Inc.
        170 West Tasman Drive
        San Jose, CA 95134





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        408-527-3711
        abierman@cisco.com

        Keith McCloghrie
        Cisco Systems Inc.
        170 West Tasman Drive
        San Jose, CA 95134
        408-526-5260
        kzm@cisco.com"
    DESCRIPTION
            "The MIB module for describing PDP data elements."
    ::= { experimental xx }

pdpDataMIBObjects   OBJECT IDENTIFIER ::= { pdpDataMIB 1 }

-- MIB groups
pdpDataElements     OBJECT IDENTIFIER ::= { pdpDataMIBObjects 1 }

--
--  ***********************************************************
--
--              P D P    D A T A    E L E M E N T S
--
--  ***********************************************************
--


pdpChassisIdType OBJECT-TYPE
    SYNTAX      PtopoChassisIdType
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "This object identifies the type of chassis component
            identifier contained in the pdpChassisId object, within a
            given PDP message."
    ::= { pdpDataElements 1 }

pdpChassisId OBJECT-TYPE
    SYNTAX      PtopoChassisId
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "This object identifies the chassis component of the
            particular connection endpoint identifier containing the PDP
            agent transmitting PDP messages.





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            If the chassis ID is unknown for the entry, then this object
            will contain an empty string."
    ::= { pdpDataElements 2 }

pdpPortIdType OBJECT-TYPE
    SYNTAX      PtopoPortIdType
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "This object identifies the type of port component
            identifier contained in the pdpPortId object, within a given
            PDP message."
    ::= { pdpDataElements 3 }

pdpPortId OBJECT-TYPE
    SYNTAX      PtopoPortId
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "This object identifies the port component of a particular
            connection endpoint identifier, associated with the port
            chosen for transmission of a given PDP message.

            For PDP agents contained within repeaters or concentrators,
            this object may identify the backplane component chosen for
            transmission of a given PDP message, instead of a specific
            port component (attached to the identified backplane).

            If the port ID is unknown for the entry, then this object
            will contain an empty string."
    ::= { pdpDataElements 4 }

pdpMgmtAddrType OBJECT-TYPE
    SYNTAX      IANAAddrFamily
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "This object identifies the type of network address
            contained in the pdpMgmtAddr object, within a given PDP
            message."
    ::= { pdpDataElements 5 }

pdpMgmtAddr OBJECT-TYPE
    SYNTAX      PtopoGenAddr
    MAX-ACCESS  read-only





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    STATUS      current
    DESCRIPTION
            "This object identifies a particular network address,
            associated with an SNMP agent which contains additional
            information pertaining to the connection endpoint identified
            in a given PDP message.

            If a management address is unknown for the endpoint
            described in a given PDP message, then this object will
            contain an empty string."
    ::= { pdpDataElements 6 }



-- conformance information
pdpDataConformance OBJECT IDENTIFIER ::= { pdpDataMIB 2 }

pdpDataCompliances OBJECT IDENTIFIER ::= { pdpDataConformance 1 }
pdpDataGroups      OBJECT IDENTIFIER ::= { pdpDataConformance 2 }

-- compliance statements

pdpDataCompliance MODULE-COMPLIANCE
   STATUS  current
    DESCRIPTION
            "The compliance statement for entities which implement the
            PTOPO Discovery Protocol."
    MODULE  -- this module
        MANDATORY-GROUPS { pdpPtopoDataGroup }

    ::= { pdpDataCompliances 1 }

-- MIB groupings

pdpPtopoDataGroup    OBJECT-GROUP
    OBJECTS {
        pdpChassisIdType,
        pdpChassisId,
        pdpPortIdType,
        pdpPortId,
        pdpMgmtAddrType,
        pdpMgmtAddr
    }
    STATUS  current
    DESCRIPTION





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            "The collection of objects which identify connection
            endpoint data elements, as used in the PTOPO Discovery
            Protocol, and represented in the PTOPO MIB.

            This group is mandatory for agents which implement the PTOPO
            Discovery Protocol."
    ::= { pdpDataGroups 1 }

END


4.5.  Protocol Operation

An active PDP Agent must perform the following tasks:

   - transmit PDP messages
   - process received PDP messages
   - maintain an instance of the PDP MIB
   - maintain an instance of the PTOPO MIB
   - maintain appropriate ifEntry and/or entPhysicalEntry instances
   - implement ifAlias and/or entPhysicalAlias MIB objects


4.5.1.  Protocol Initialization

Upon system reinitialization, the following tasks are performed by the
PDP agent:

     Non-volatile configuration for the PDP MIB is retrieved if
     applicable, otherwise appropriate default values are assigned to
     all PDP configuration variables.

     If pdpAdminStatus is equal to 'disabled(2)', then PDP
     initialization is terminated (until such time that the
     pdpAdminStatus object is set to 'enabled(1)'), otherwise continue.

     Internal (implementation-specific) data structures are initialized.
     such that appropriate local physical topology information and PDP
     transmission parameters are set.


4.5.2.  Message Encoding

This section does not assume a particular buffering strategy, and such
details are omitted.





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4.5.2.1.  Header Fields

The version field is set to one (0x01).

The flags field is set to zero (0x00).

The time-to-live field is set to the value obtained by the following
formula:

TTL = min(65535, (pdpMessageTxInterval * pdpMessageTxHoldMultiplier))


4.5.2.2.  VarBindList

Each message must contain one instance of each of the six mandatory
PDP-PDU data elements, defined in the PDP Data MIB.  Additional data
elements may be added as maximum frame size permits.

ASN.1/BER encoding is defined in [TBD], and is outside the scope of this
document.


4.5.3.  Message Transmission

An active PDP agent must transmit a PDP message out each appropriate
port, once each message interval, as determined by the
pdpMessageTxInterval MIB object. Messages transmitted on repeater
devices may be sent for each repeater backplane, once per message
interval. Actual transmission intervals should be jittered to prevent
synchronization effects.

Note that the agent must suppress the transmission of multiple PDP
messages during a single message interval, in the event message
transmission cannot be restricted to a single port, but rather a group
of ports (e.g., a repeater device).

In this case, a single port in the port group should be selected (in an
implementation-specific manner) to represent the port group. Note that
an agent is encouraged to represent port groups as 'backplanes', in the
entPhysicalTable of the Entity MIB, rather than individual ports in
either the Entity MIB or Interfaces MIB.

Regarding the transmission of a single PDP message, for the indicated
physical interface contained in the local system:






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     The PDP agent checks for the existence of a pdpSuppressEntry for
     the port.  If an entry exists then this port is skipped, otherwise
     continue.

     The PDP message is encapsulated as appropriate for the port.

     The MAC header is filled in with appropriate SA and DA and
     EtherType fields.  (Ignoring LLC/SNAP details).

     The frame is transmitted or passed to a lower layer for
     transmission.

     The pdpStatsOutPkts counter is incremented for the indicated local
     port.


4.5.4.  Received Message Processing

An active PDP agent must process PDP messages received on each
appropriate port, as such messages arrive.

The following sections refer to the reception of a single PDP message,
for the indicated physical interface contained in the local system:


4.5.4.1.  Header Fields

The PDP message and the chassis/port indices associated with the
receiving port are retrieved.

The PDP version and flags field are checked.  The version should equal
one (0x01) and the flags should equal zero (0x00).  If not, the
pdpStatsInErrors counter for the receiving port is incremented and
processing is terminated; otherwise continue.


4.5.4.2.  VarBindList

The ASN.1/BER portion of the message is decoded.  (Such parsing
techniques are beyond the scope of this document.) If this portion of
the PDP message is not properly encoded, as defined in the PDP Data MIB,
then the pdpStatsInErrors counter for the receiving port is incremented,
and processing is terminated; otherwise continue.

The list of data elements is examined. The agent must skip and ignore





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PDU data elements unknown to the agent.  If any of the mandatory data
elements are missing, then the pdpStatsInErrors counter for the
receiving port is incremented, and processing is terminated; otherwise
continue.

The pdpStatsInGoodPkts counter is incremented for the receiving port.


4.5.4.3.  PTOPO MIB Update

If the time-to-live field in the PDP message header is zero then execute
this interface shutdown procedure, described below.  Processing of the
PDP message is now complete.

If the time-to-live field is non-zero, then the appropriate
ptopoConnEntry is found or created, based on the data elements included
in the PDP message. If the indicated entry is dynamic (i.e.,
ptopoConnIsStatic is true), then the current sysUpTime value is stored
in the ptopoConnLastVerifyTime field for the entry.

If a ptopoConnEntry was added then the ptopoConnTabInserts counter is
incremented.

If a ptopoConnEntry of one type was replaced with an entry of a
different type, then the ptopoConnTabReplaces counter is incremented.

If any ptopoConnEntry was added or deleted, or if information other than
the ptopoConnLastVerifyTime changed for any entry due to the processing
of this PDP message, then the ptopoLastChangeTime object is set with the
current sysUpTime, and a ptopoConfigChange trap event is generated. (See
the PTOPO MIB for information on ptopoConfigChange trap generation.)


4.5.5.  Interface Shutdown Procedure

A special procedure exists for the case in which a PDP agent knows a
particular port is about to become non-operational.

Note that the pdpSuppressTable has precedence over these procedures, and
they are only executed if the indicated interface is not specified in
the pdpSuppressTable.

If any entries are deleted as a result of these procedures, the
ptopoConnTabDeletes counter is incremented for each deleted entry.






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4.5.5.1.  PDP Shutdown Transmission

In the event an interface, currently configured with PDP message
transmission enabled, either becomes disabled for PDP activity, or the
interface is administratively disabled, a final PDP message is
transmitted with a time to live value of zero (before the interface is
disabled).

In the event the pdpOperStatus is transitioning to the disabled state,
then this shutdown procedure should be executed for all local
interfaces.


4.5.5.2.  PDP Shutdown Reception

After reception of a valid PDP message with a time-to-live value equal
to zero, the PDP Agent must remove all information in the PTOPO MIB
learned from the particular PDP agent, which is associated with the
indicated remote connection endpoint.


5.  PTOPO Discovery Protocol MIB

This section defines the MIB used to configure PDP agent behavior.


5.1.  Definitions

PDP-MIB DEFINITIONS ::= BEGIN

IMPORTS
    MODULE-IDENTITY, OBJECT-TYPE, Integer32, Counter32
        FROM SNMPv2-SMI
    RowStatus
        FROM SNMPv2-TC
    MODULE-COMPLIANCE, OBJECT-GROUP
        FROM SNMPv2-CONF
    PhysicalIndex
        FROM ENTITY-MIB;

pdpMIB MODULE-IDENTITY
    LAST-UPDATED "9707300000Z"
    ORGANIZATION "IETF PTOPOMIB Working Group"
    CONTACT-INFO
       "PTOPOMIB WG Discussion:





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        ptopo@3com.com
        Subscription:
        majordomo@3com.com
          msg body: [un]subscribe ptopomib

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

        Keith McCloghrie
        Cisco Systems Inc.
        170 West Tasman Drive
        San Jose, CA 95134
        408-526-5260
        kzm@cisco.com"
    DESCRIPTION
            "The MIB module for managing the Physical Topology Discovery
            Protocol."
    ::= { experimental xx }

pdpMIBObjects   OBJECT IDENTIFIER ::= { pdpMIB 1 }

-- MIB groups
pdpConfig    OBJECT IDENTIFIER ::= { pdpMIBObjects 1 }
pdpStats     OBJECT IDENTIFIER ::= { pdpMIBObjects 2 }


PdpPortIdType ::=  TEXTUAL-CONVENTION
    STATUS        current
    DESCRIPTION
            "The type of index value used to represent a port component.

            If an object of this type has a value of 'ifIndexType(1)',
            then the associated 'port ID' value represents an ifEntry,
            with the same ifIndex value.

            If an object of this type has a value of
            'entPhysicalIndexType(2)', then the associated 'port ID'
            value represents an entPhysicalEntry, with the same
            entPhysicalIndex value."
    SYNTAX        INTEGER  {
                     ifIndexType(1),





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                     entPhysicalIndexType(2)
                  }

--
--  ***********************************************************
--
--                    P D P    C O N F I G
--
--  ***********************************************************
--
--   The Physical Topology Discovery Protocol Configuration Group

pdpAdminStatus OBJECT-TYPE
    SYNTAX      INTEGER  {
                        enabled(1),
                        disabled(2)
                }
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "The administratively desired status of the the local PDP
            agent.

            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."
    ::= { pdpConfig 1 }

pdpOperStatus OBJECT-TYPE
    SYNTAX      INTEGER  {
                        enabled(1),
                        disabled(2)
                }
    MAX-ACCESS  read-only
    STATUS      current
    DESCRIPTION
            "The current operational status of the local PDP agent."
    ::= { pdpConfig 2 }

pdpMessageTxInterval OBJECT-TYPE
    SYNTAX      Integer32 (5..32768)
    UNITS       "seconds"
    MAX-ACCESS  read-write
    STATUS      current





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    DESCRIPTION
            "The interval at which PDP messages are transmitted on
            behalf of this PDP agent.

            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       { 60 }
    ::= { pdpConfig 3 }

pdpMessageTxHoldMultiplier OBJECT-TYPE
    SYNTAX      Integer32 (2..10)
    MAX-ACCESS  read-write
    STATUS      current
    DESCRIPTION
            "The time-to-live value expressed as a multiple of the
            pdpMessageTxInterval object.  The actual time-to-live value
            used in PDP messages, transmitted on behalf of this PDP
            agent, can be expressed by the following formula:

            TTL = min(65535, (pdpMessageTxInterval * pdpMessageTxHoldMultiplier))

            For example, if the value of pdpMessageTxInterval is '60',
            and the value of pdpMessageTxHoldMultiplier is '3', then the
            value '180' is encoded in the TTL field in the PDP header.

            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        { 3 }
    ::= { pdpConfig 4 }

--
-- PdpSuppressTable:
--   Disable PDP activity on individual local ports

pdpSuppressTable   OBJECT-TYPE
    SYNTAX      SEQUENCE OF PdpSuppressEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "A table controlling PDP message transmission on individual
            interfaces, ports, or backplanes."





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    ::= { pdpConfig 6 }

pdpSuppressEntry   OBJECT-TYPE
    SYNTAX      PdpSuppressEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "PDP message configuration information for a particular
            port.  The port must be contained in the same chassis as the
            PDP agent. PDP messages will not be transmitted or received
            on the indicated port, even if the port is enabled.

            If the agent is capable of storing non-volatile
            configuration, then each active pdpSuppressEntry must be
            re-created after a re-initialization of the management
            system.  An agent should store enough information about the
            associated entPhysicalEntry (e.g., entPhysicalAlias) or
            ifEntry (e.g. ifAlias), to properly re-create the entry,
            even if the pdpSuppressChassisId and/or pdpSuppressPortId
            values change across a system re-initialization."
    INDEX  {
        pdpSuppressChassisId,
        pdpSuppressPortIdType,
        pdpSuppressPortId
    }
    ::= { pdpSuppressTable 1 }

PdpSuppressEntry ::= SEQUENCE {
      pdpSuppressChassisId       PhysicalIndex,
      pdpSuppressPortIdType      PdpPortIdType,
      pdpSuppressPortId          Integer32,
      pdpSuppressRowStatus       RowStatus
}

pdpSuppressChassisId  OBJECT-TYPE
    SYNTAX      PhysicalIndex
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "The entPhysicalIndex value used to identify the chassis
            component associated with this entry. The associated
            entPhysicalEntry must be active, and the associated
            entPhysicalClass object must be equal to 'chassis(3)'."
    ::= { pdpSuppressEntry 1 }






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pdpSuppressPortIdType OBJECT-TYPE
    SYNTAX        PdpPortIdType
    MAX-ACCESS    not-accessible
    STATUS        current
    DESCRIPTION
            "The type of index value contained in the associated
            pdpSuppressPortId object."
    ::= { pdpSuppressEntry 2 }

pdpSuppressPortId    OBJECT-TYPE
    SYNTAX      Integer32  (1..2147483647)
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "The index value used to identify the port component of this
            entry.  The type of index value depends on the
            pdpSuppressPortIdType value for this entry.

            If the associated pdpSuppressPortIdType is equal to
            'ifIndexType(1)', then  this pdpSuppressPortId represents an
            ifEntry with the same ifIndex value.  The associated ifEntry
            must be active, and represent a physical interface on the
            local chassis.

            If the associated pdpSuppressPortIdType is equal to
            'entPhysicalIndexType(2)', then this pdpSuppressPortId
            represents an entPhysicalEntry with the same
            entPhysicalIndex value.  The associated entPhysicalEntry
            must be active, and the associated entPhysicalClass object
            must be equal to 'port(10)' or 'backplane(4)'.

            Note that some devices, such as repeaters, cannot restrict
            frame transmission to a single port, but rather to a group
            of ports.  In such an event, an agent will disable PDP
            activity on all ports in the port group, if any of the
            individual ports in the group are specified in this table."
    ::= { pdpSuppressEntry 3 }

pdpSuppressRowStatus  OBJECT-TYPE
    SYNTAX        RowStatus
    MAX-ACCESS    read-create
    STATUS        current
    DESCRIPTION
            "The status of this entry."
    ::= { pdpSuppressEntry 4 }





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--
--  ***********************************************************
--
--                   P D P    S T A T S
--
--  ***********************************************************
--
-- PDP Stats Group

pdpStatsTable   OBJECT-TYPE
    SYNTAX      SEQUENCE OF PdpStatsEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "A table containing PDP statistics for individual ports.

            Entries are not required to exist in this table while the
            pdpAdminStatus or pdpOperStatus objects are equal to
            'disabled(2)'.

            Entries are not required to exist in this table if a
            corresponding entry (with identical index values) exists in
            the pdpSuppressTable."
    ::= { pdpStats 1 }

pdpStatsEntry   OBJECT-TYPE
    SYNTAX      PdpStatsEntry
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "PDP message statistics for a particular port.  The port
            must be contained in the same chassis as the PDP agent."
    INDEX  {
             pdpStatsChassisId,
             pdpStatsPortIdType,
             pdpStatsPortId
    }
    ::= { pdpStatsTable 1 }

PdpStatsEntry ::= SEQUENCE {
      pdpStatsChassisId       PhysicalIndex,
      pdpStatsPortIdType      PdpPortIdType,
      pdpStatsPortId          Integer32,
      pdpStatsInGoodPkts      Counter32,
      pdpStatsInErrors        Counter32,





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      pdpStatsOutPkts         Counter32
}

pdpStatsChassisId  OBJECT-TYPE
    SYNTAX      PhysicalIndex
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "The entPhysicalIndex value used to identify the chassis
            component associated with this entry. The associated
            entPhysicalEntry must be active, and the associated
            entPhysicalClass object must be equal to 'chassis(3)'."
    ::= { pdpStatsEntry 1 }

pdpStatsPortIdType OBJECT-TYPE
    SYNTAX        PdpPortIdType
    MAX-ACCESS    not-accessible
    STATUS        current
    DESCRIPTION
            "The type of index value contained in the associated
            pdpStatsPortId object."
    ::= { pdpStatsEntry 2 }

pdpStatsPortId    OBJECT-TYPE
    SYNTAX      Integer32  (1..2147483647)
    MAX-ACCESS  not-accessible
    STATUS      current
    DESCRIPTION
            "The index value used to identify the port component of this
            entry.  The type of index value depends on the
            pdpStatsPortType value for this entry.

            If the associated pdpStatsPortIdType is equal to
            'ifIndexType(1)', then  this pdpStatsPortId represents an
            ifEntry with the same ifIndex value.  The associated ifEntry
            must be active, and represent a physical interface on the
            local chassis.

            If the associated pdpStatsPortIdType is equal to
            'entPhysicalIndexType(2)', then this pdpStatsPortId
            represents an entPhysicalEntry with the same
            entPhysicalIndex value.  The associated entPhysicalEntry
            must be active, and the associated entPhysicalClass object
            must be equal to 'port(10)' or 'backplane(4)'."
    ::= { pdpStatsEntry 3 }





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pdpStatsInGoodPkts  OBJECT-TYPE
    SYNTAX        Counter32
    MAX-ACCESS    read-only
    STATUS        current
    DESCRIPTION
            "The number of valid PDP messages received by this PDP agent
            on the indicated port, while this PDP agent is enabled."
    ::= { pdpStatsEntry 4 }

pdpStatsInErrors  OBJECT-TYPE
    SYNTAX        Counter32
    MAX-ACCESS    read-only
    STATUS        current
    DESCRIPTION
            "The number of invalid PDP messages received by this PDP
            agent on the indicated port, while this PDP agent is
            enabled. A PDP message may be invalid for several reasons,
            including:
               - invalid MAC header; length or DA fields
               - invalid PDP header; version or flags fields
               - invalid PDP VarBindList ASN.1/BER encoding
               - invalid or missing PDP VarBindList data elements"
    ::= { pdpStatsEntry 5 }

pdpStatsOutPkts  OBJECT-TYPE
    SYNTAX        Counter32
    MAX-ACCESS    read-only
    STATUS        current
    DESCRIPTION
            "The number of PDP messages transmitted by this PDP agent on
            the indicated port."
    ::= { pdpStatsEntry 6 }


-- conformance information
pdpConformance OBJECT IDENTIFIER ::= { pdpMIB 2 }

pdpCompliances OBJECT IDENTIFIER ::= { pdpConformance 1 }
pdpGroups      OBJECT IDENTIFIER ::= { pdpConformance 2 }

-- compliance statements

pdpCompliance MODULE-COMPLIANCE
   STATUS  current
    DESCRIPTION





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            "The compliance statement for SNMP entities which implement
            the PDP MIB."
    MODULE  -- this module
        MANDATORY-GROUPS { pdpConfigGroup, pdpStatsGroup }

    ::= { pdpCompliances 1 }

-- MIB groupings

pdpConfigGroup    OBJECT-GROUP
    OBJECTS {
        pdpAdminStatus,
        pdpOperStatus,
        pdpMessageTxInterval,
        pdpMessageTxHoldMultiplier,
        pdpSuppressRowStatus
    }
    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to configure the
            PTOPO Discovery Protocol implementation behavior.

            This group is mandatory for agents which implement the PTOPO
            Discovery Protocol."
    ::= { pdpGroups 1 }

pdpStatsGroup    OBJECT-GROUP
    OBJECTS {
        pdpStatsInGoodPkts,
        pdpStatsInErrors,
        pdpStatsOutPkts
    }
    STATUS  current
    DESCRIPTION
            "The collection of objects which are used to represent PTOPO
            Discovery Protocol statistics.

            This group is mandatory for agents which implement the PTOPO
            Discovery Protocol."
    ::= { pdpGroups 2 }

END








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6.  Acknowledgements

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














































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7.  References

[ENTITY-EXT]
     Bierman, A., McCloghrie, K., "Entity MIB Extensions for Persistent
     Component Identification", draft-bierman-entmib-compid-00.txt,
     Cisco Systems, July 1997.

[PTOPO]
     Bierman, A., Jones, K., "Physical Topology MIB", draft-ietf-
     ptopomib-mib-00.txt, Cisco Systems, Bay Networks, July 1997.

[RFC1157]
     Case, J., M. Fedor, M. Schoffstall, J. Davin, "Simple Network
     Management Protocol", RFC 1157, SNMP Research, Performance Systems
     International, MIT Laboratory for Computer Science, May 1990.

[RFC1213]
     McCloghrie, K., and M. Rose, Editors, "Management Information Base
     for Network Management of TCP/IP-based internets: MIB-II", STD 17,
     RFC 1213, Hughes LAN Systems, Performance Systems International,
     March 1991.

[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,
     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, 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, 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, January 1996.

[RFC2037]
     McCloghrie, K., Bierman, A., "Entity MIB using SMIv2", RFC 2037,





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     Cisco Systems, October 1996.

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













































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8.  Security Considerations

This protocol and associated MIB can expose the existence of physical
components, MAC layer addresses, and network layer addresses, pertaining
to devices within a given network.  A network administrator may wish to
restrict access to this management information, using SNMP access
control mechanisms, and restrict PDP message processing to a particular
set of ports, by configuring entries in the pdpSuppressTable.


9.  Authors' Addresses

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

     Keith McCloghrie
     Cisco Systems, Inc.
     170 West Tasman Drive
     San Jose, CA 95134
     Phone: 408-526-5260
     Email: kzm@cisco.com

























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Table of Contents


1 Introduction ....................................................    1
2 The SNMP Network Management Framework ...........................    2
2.1 Object Definitions ............................................    2
3 Overview ........................................................    2
3.1 Terms .........................................................    3
3.2 Persistent Identifiers ........................................    3
3.3 Relationship to the Physical Topology MIB .....................    3
3.4 Relationship to Entity MIB ....................................    3
3.5 Relationship to Interfaces MIB ................................    4
4 PTOPO Discovery Protocol ........................................    4
4.1 Frame Encapsulation ...........................................    4
4.2 PDP Forwarding ................................................    5
4.3 PDP Message Format ............................................    5
4.3.1 PDP Header Format ...........................................    5
4.3.2 PDP PDU Encoding ............................................    6
4.4 PDP Data MIB ..................................................    8
4.4.1 Definitions .................................................    8
4.5 Protocol Operation ............................................   12
4.5.1 Protocol Initialization .....................................   12
4.5.2 Message Encoding ............................................   12
4.5.2.1 Header Fields .............................................   13
4.5.2.2 VarBindList ...............................................   13
4.5.3 Message Transmission ........................................   13
4.5.4 Received Message Processing .................................   14
4.5.4.1 Header Fields .............................................   14
4.5.4.2 VarBindList ...............................................   14
4.5.4.3 PTOPO MIB Update ..........................................   15
4.5.5 Interface Shutdown Procedure ................................   15
4.5.5.1 PDP Shutdown Transmission .................................   16
4.5.5.2 PDP Shutdown Reception ....................................   16
5 PTOPO Discovery Protocol MIB ....................................   16
5.1 Definitions ...................................................   16
6 Acknowledgements ................................................   26
7 References ......................................................   27
8 Security Considerations .........................................   29
9 Authors' Addresses ..............................................   29











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