Internet Engineering Task Force (IETF) A. Koushik
Request for Comments: 7420 Brocade Communications, Inc.
Category: Standards Track E. Stephan
ISSN: 2070-1721 Orange
Old Dog Consulting
December 2014 Path Computation Element Communication Protocol (PCEP)
Management Information Base (MIB) Module
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 for modeling of the Path
Computation Element Communication Protocol (PCEP) for communications
between a Path Computation Client (PCC) and a Path Computation
Element (PCE), or between two PCEs.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
The PCE defined in [RFC4655] is an entity that is capable of
computing a network path or route based on a network graph and
applying computational constraints. A PCC may make requests to a PCE
for paths to be computed.
PCEP is the communication protocol between a PCC and PCE and is
defined in [RFC5440]. PCEP interactions include path computation
requests and path computation replies as well as notifications of
specific states related to the use of a PCE in the context of
Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS)
Traffic Engineering (TE).
This memo defines a portion of the MIB for use with network
management protocols in the Internet community. In particular, it
defines a MIB module that can be used to monitor PCEP interactions
between a PCC and a PCE, or between two PCEs.
The scope of this document is to provide a MIB module for the PCEP
base protocol defined in [RFC5440]. Extensions to the PCEP base
protocol are beyond the scope for this document.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this
document are to be interpreted as described in BCP 14 [RFC2119].
This document uses the terminology defined in [RFC4655] and
[RFC5440]. In particular, it uses the following acronyms.
o Path Computation Request (PCReq) message.
o Path Computation Reply (PCRep) message.
o Notification (PCNtf) message.
o Error (PCErr) message.
o Request Parameter (RP) object.
o Synchronization Vector (SVEC) object.
o Explicit Route Object (ERO).
This document uses the term "PCEP entity" to refer to a local PCEP
speaker, "peer" to refer to a remote PCEP speaker, and "PCEP speaker"
where it is not necessary to distinguish between local and remote.
2. The Internet-Standard Management Framework
For a detailed overview of the documents that describe the current
Internet-Standard Management Framework, please refer to section 7 of
RFC 3410 [RFC3410].
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. MIB objects are generally
accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the
Structure of Management Information (SMI). This memo specifies a MIB
module that is compliant to the SMIv2, which is described in STD 58,
RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579], and STD 58, RFC 2580
3. PCEP MIB Module Architecture
The PCEP MIB module contains the following information:
a. PCE and PCC local entity status (see pcePcepEntityTable).
b. PCEP peer information (see pcePcepPeerTable).
c. PCEP session information (see pcePcepSessTable).
d. Notifications to indicate PCEP session changes.
The PCEP MIB module is limited to "read-only" access except for
pcePcepNotificationsMaxRate, which is used to throttle the rate at
which the implementation generates notifications.
The PCEP MIB module may contain status information for multiple
logical local PCEP entities. There are several scenarios in which
there may be more than one local PCEP entity, including the
o A physical router, which is partitioned into multiple virtual
routers, each with its own PCC.
o A PCE device that front ends a cluster of compute resources, each
with a different set of capabilities that are accessed via
different IP addresses.
The pcePcepEntityTable contains one row for each local PCEP entity.
Each row is read-only and contains current status information, plus
the PCEP entity's running configuration.
The pcePcepEntityTable is indexed by pcePcepEntityIndex, which also
acts as the primary index for the other tables in this MIB module.
The pcePcepPeerTable contains one row for each peer that the local
PCEP entity knows about. Each row is read-only and contains
information to identify the peer, the running configuration relating
to that peer, and statistics that track the messages exchanged with
that peer and its response times.
A PCEP speaker is identified by its IP address. If there is a PCEP
speaker in the network that uses multiple IP addresses, then it looks
like multiple distinct peers to the other PCEP speakers in the
The pcePcepPeerTable is indexed first by pcePcepEntityIndex, then by
pcePcepPeerAddrType and pcePcepPeerAddr. This indexing structure
allows each local PCEP entity to report its own set of peers.
Since PCEP sessions can be ephemeral, pcePcepPeerTable tracks a peer
even when no PCEP session currently exists to that peer. The
statistics contained in pcePcepPeerTable are an aggregate of the
statistics for all successive sessions to that peer.
To limit the quantity of information that is stored, an
implementation MAY choose to discard a row from pcePcepPeerTable if
and only if no PCEP session exists to the corresponding peer.
The pcePcepSessTable contains one row for each PCEP session that the
PCEP entity (PCE or PCC) is currently participating in. Each row is
read-only and contains the running configuration that is applied to
the session, plus identifiers and statistics for the session.
The statistics in pcePcepSessTable are semantically different from
those in pcePcepPeerTable since the former applies to the current
session only, whereas the latter is the aggregate for all sessions
that have existed to that peer.
Although it is forbidden per [RFC5440] to have more than one active
PCEP session between a given pair of PCEP entities at any one time,
there is a window during session establishment where the
pcePcepSessTable may contain two rows for a given peer, one
representing a session initiated by the local PCEP entity and one
representing a session initiated by the peer. If either of these
sessions reaches an active state, then the other is discarded.
The pcePcepSessTable is indexed first by pcePcepEntityIndex, then by
pcePcepPeerAddrType and pcePcepPeerAddr, and finally by
pcePcepSessInitiator. This indexing structure allows each local PCEP
entity to report its own set of active sessions. The
pcePcepSessInitiator index allows two rows to exist transiently for a
given peer, as discussed above.
3.4. PCEP Notifications
The PCEP MIB module contains notifications for the following
a. pcePcepSessUp: PCEP session has gone up.
b. pcePcepSessDown: PCEP session has gone down.
c. pcePcepSessLocalOverload: Local PCEP entity has sent an overload
PCNtf on this session.
d. pcePcepSessLocalOverloadClear: Local PCEP entity has sent an
overload-cleared PCNtf on this session.
e. pcePcepSessPeerOverload: Peer has sent an overload PCNtf on this
f. pcePcepSessPeerOverloadClear: Peer has sent an overload-cleared
PCNtf on this session.
3.5. Relationship to Other MIB Modules
The PCEP MIB module imports the following textual conventions from
the INET-ADDRESS-MIB defined in RFC 4001 [RFC4001]:
PCEP relies on existing protocols that have specialized MIB objects
to monitor their own activities. Consequently, this document
considers that the monitoring of underlying protocols is out of scope
of the PCEP MIB module.