ID Summary: draft-smith-mpls-ldp-restart-00.txt

["Andrew G. Malis" <Andy.Malis@vivacenetworks.com>]

ID Name: 
http://www.ietf.org/internet-drafts/draft-smith-mpls-ldp-restart-00.txt

ID Title: Graceful Restart Mechanism for LDP

- Summary:

  This document proposes a lightweight mechanism that the LDP
  protocol may use to help minimize the impact introduced by
  transient interruptions to an LDP session, with a focus on
  connection preservation for signaled Layer 2 circuits.  A new
LDP
  Cork message request/response mechanism is specified. New
message
  types are defined for the delivery of graceful restart
events.
  Finally, procedures for utilizing this mechanism are
detailed.

  The procedure described in this draft has excellent scaling
  properties: the LDP state is preserved incrementally, such
that
  after an unexpected restart of an LDP session, only the LDP
  activity not already acknowledged during the previous 
session
  needs to be resignaled.  In the case of provisioned Layer
2
  circuits, it is probable that no resignaling will be
necessary.

  The procedure described in this draft is minimally invasive
to
  the LDP state machine and requires no changes to the LDP
  message processing procedures.

- Where does it fit in the Picture of the Sub-IP Area

  This ID fits in the MPLS WG.

- Why is it targeted at this WG

  This draft proposes LDP graceful recovery as a lightweight
fault
  tolerance mechanism for LDP targeted sessions, which is in the
  MPLS WG's current charter.

- Justification

  This draft adds the ability for LDP to gracefully recover
from
  failed LDP or TCP sessions between a pair of LDP peers, with
  bounded recovery time and minimal restoration signaling. It
also
  does not require changes to normal LDP message processing.
This
  draft is especially well-suited for use in conjunction with
  targeted LDP sessions for layer 2 circuits within LSP
tunnels.