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The Accumulated IGP Metric Attribute for BGP
RFC 7311

Approval announcement
Draft of message to be sent after approval:


From: The IESG <>
To: IETF-Announce <>
Cc: RFC Editor <>,
    idr mailing list <>,
    idr chair <>
Subject: Protocol Action: 'The Accumulated IGP Metric Attribute for BGP' to Proposed Standard (draft-ietf-idr-aigp-18.txt)

The IESG has approved the following document:
- 'The Accumulated IGP Metric Attribute for BGP'
  (draft-ietf-idr-aigp-18.txt) as Proposed Standard

This document is the product of the Inter-Domain Routing Working Group.

The IESG contact persons are Alia Atlas and Adrian Farrel.

A URL of this Internet Draft is:

Ballot Text

Technical Summary

   Routing protocols that have been designed to run within a single
   administrative domain ("IGPs") generally do so by assigning a metric
   to each link, and then choosing as the installed path between two
   nodes the path for which the total distance (sum of the metric of
   each link along the path) is minimized.  BGP, designed to provide
   routing over a large number of independent administrative domains
   ("autonomous systems"), does not make its path selection decisions
   through the use of a metric.  It is generally recognized that any
   attempt to do so would incur significant scalability problems, as
   well as inter-administration coordination problems.  However, there
   are deployments in which a single administration runs several
   contiguous BGP networks.  In such cases, it can be desirable, within
   that single administrative domain, for BGP to select paths based on a
   metric, just as an IGP would do.  The purpose of this document is to
   provide a specification for doing so.

Working Group Summary

The working actively reviewed this draft considering the following: 

a) error handling with malformed packets or malformed transitive bits,
b) placement of AIGP TLV in the draft;  
c) default setting for AIGP_SESSION on IBGP setting at SHOULD be "enabled"
  (AIGP_SESSION aids flagging the AIGP packets exiting the 
   restricted environment to the wild),  

d) AIGP value is capped at maximum. This value cannot wrap, and
   any attempts to increase it past its maximum is treated as 
   a malformed packet, and  
e) TLV formatting.. 

Document Quality

This  WG draft has been implemented by 3 vendors (including Juniper and Cisco), and seen deployment in ISPs.  The debates around this draft have been resolved by the authors by the -14 draft. Shepherd did editorial pass on the draft, and the authors address the nits that shepherd found. 

Reviewers on the list were interested and complete in their review. The reviewers on the IDR list included long-time experts, newer implementers, deployment
and research.  While additional review is always good, this was a good review. 

IPR LC was done based on two disclosures from cisco:
id #1159, #1160.  No concerns were raised. 

Reviews done: 

Early OPS-IDR review by Ron Bonica resulted in several changes, and Ron Bonica
approving the document.  An Early IANA Review also resulted in changes. No comments were received from an early request for a Routing Directorate review. 
No MIB Doctor review is relevant for this review outside an OPS-DIR review. 

  Shepherd: Susan Hares (WG chair) 
  WG chairs: John Scudder and Susan Hares
  AD: Alia Atlas


RFC Editor Note