Applicability of MPLS Transport Profile for Ring Topologies
RFC 6974

Approval announcement
Draft of message to be sent after approval:

From: The IESG <iesg-secretary@ietf.org>
To: IETF-Announce <ietf-announce@ietf.org>
Cc: RFC Editor <rfc-editor@rfc-editor.org>,
    mpls mailing list <mpls@ietf.org>,
    mpls chair <mpls-chairs@tools.ietf.org>
Subject: Document Action: 'Applicability of MPLS-TP Linear Protection for Ring Topologies' to Informational RFC (draft-ietf-mpls-tp-ring-protection-06.txt)

The IESG has approved the following document:
- 'Applicability of MPLS-TP Linear Protection for Ring Topologies'
  (draft-ietf-mpls-tp-ring-protection-06.txt) as Informational RFC

This document is the product of the Multiprotocol Label Switching Working
Group.

The IESG contact persons are Adrian Farrel and Stewart Bryant.

A URL of this Internet Draft is:
http://datatracker.ietf.org/doc/draft-ietf-mpls-tp-ring-protection/


Technical Summary

   This document presents an applicability of existing MPLS protection
   mechanisms, both local and end-to-end, to Multi-Protocol Label
   Switching Transport Profile (MPLS-TP) in ring topologies.  This
   document does not propose any new mechanisms or protocols.
   Protection on rings offers a number of opportunities for optimization
   as the protection choices are starkly limited (all traffic traveling
   one way around a ring can only be switched to travel the other way on
   the ring), but also suffers from some complications caused by the
   limitations of the topology.

   Requirements for MPLS-TP protection especially for protection in ring
   topologies are discussed in "Requirements of an MPLS Transport
   Profile" (RFC 5654) and "MPLS Transport Profile (MPLS-TP)
   Survivability Framework" (RFC 6372).  This document shows how MPLS-TP
   linear protection as defined in RFC 6378 can be applied to single
   ring topologies, discusses how most of the requirements are met, and
   describes scenarios in which the function provided by applying linear
   protection in a ring topology falls short of some of the
   requirements.

Working Group Summary

   This document was the subject of considerable debate in the MPLS
   working group. There was some concern about whether this work
   prohibited or devalued the development of specialised protection
   techniques for deployment in ring topologies.

   The document was re-worked to make it clear that it is basically
   an applicability statement showing how linear protection defined 
   in RFC 6378 can be applied to ring topologies, what function can
   be achieved, and what issues remain. It was made clear to the
   working group that specialist ring protection techniques were still
   in scope for the working group provided that they demonstrate 
   improvements over the application of linear protection, and provided
   they can interwork with general protection in the wider MPLS-TP
   network.

   A second WG last call was held and the document gained consensus.

   Please see RFC editor note for a commentary on the number of 
   front-page authors.

Document Quality 

   This an informational document, it describes how the technologies 
   defined in earlier RFCs can be applied to ring topologies. 

   The document has been reviewed needed, the working 
   group last call was brought to the attention of SG15 in 
   ITU-T. 

Personnel 

   Loa Andersson (loa@pi.nu) is the document shepherd 
   Adrian Farrel (Adrian@olddog.co.uk) is the Responsible AD

RFC Editor Note

   Please allow an exception to the normal front-page limit so 
   that all eight named authors can be present.  The WG chair/
   shepherd explains it as follows:

   > Early 2010 we had 5 or 6 different drafts addressing "mpls-tp-
   > ring-protection" from one aspect or another. Most of these
   > drafts had 2 or maybe 3 different authors.
   > 
   > The WG chairs took an initiative to discuss the possibilities to
   > merge all drafts into one. The discussion was partially
   > successful, and all draft but one, were merged into a single
   > document. Texts from all drafts were merged into draft-
   > weingarten-mpls-tp-ring-protection (later to be adopted as
   > the working group draft draft-ietf-mpls-tp-ring-protection.
   > 
   > The number of authors on the first page reflect text
   > contributions made to the drafts that were merged.

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You may rename and reposition Section 1.4 according to your style guide.

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If (and only if) you consider it necessary,  you may consider some of the text as Tables and apply captions as follows...

In Section 3.1 on page 19 "Table x : Backup LSPs for Node Protection"
In Section 3.1.1 on page 20 "Table x : Nodes Traversed by Protection: LSPs"
In Section 3.1.1 on page 21 "Table x : Bandwidth Utilization on Links During Protection"
In Section 3.2.2 on page 25 "Table x : Context Specific Labels for Connected LSPs"