A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Path Computation Element WG of the IETF.
Title : Inter Stateful Path Computation Element (PCE)
Communication Procedures.
Authors : Stephane Litkowski
Siva Sivabalan
Cheng Li
Haomian Zheng
Filename : draft-ietf-pce-state-sync-00.txt
Pages : 32
Date : 2021-06-28
Abstract:
The Path Computation Element Communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path
computation in response to a Path Computation Client (PCC) request.
The Stateful PCE extensions allow stateful control of Multi-Protocol
Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths
(LSPs) using PCEP.
A Path Computation Client (PCC) can synchronize an LSP state
information to a Stateful Path Computation Element (PCE). The
stateful PCE extension allows a redundancy scenario where a PCC can
have redundant PCEP sessions towards multiple PCEs. In such a case,
a PCC gives control of a LSP to only a single PCE, and only one PCE
is responsible for path computation for this delegated LSP.
There are some use cases, where an inter-PCE stateful communication
can bring additional resiliency in the design, for instance when some
PCC-PCE session fails. The inter-PCE stateful communication may also
provide a faster update of the LSP states when such an event occurs.
Finally, when, in a redundant PCE scenario, there is a need to
compute a set of paths that are part of a group (so there is a
dependency between the paths), there may be some cases where the
computation of all paths in the group is not handled by the same PCE:
this situation is called a split-brain. This split-brain scenario
may lead to computation loops between PCEs or suboptimal path
computation.
This document describes the procedures to allow a stateful
communication between PCEs for various use-cases and also the
procedures to prevent computations loops.
The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-ietf-pce-state-sync/
There is also an htmlized version available at:
https://datatracker.ietf.org/doc/html/draft-ietf-pce-state-sync-00
Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/
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