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Shepherd writeup

1. Summary

Status of administrative actions:
Public IPR Call: 11/12 to 11/19/14
Routing Directorate Review status: Joel Halpern (11/18), QA review completed
(9/4) OPS Directorate status: Reviewer: Warren Kumari (11/16) done Gen-Art
Pre-review: Pending,  10/14 IANA: No early review

Status of people
Type of draft: Proposed Standard.
The document shepherd is Rob Shakir.
The WG Chair responsible: Sue Hares   [John Scudder is co-author]
The responsible Area Director is Alia Atlas.

1. Status

The document describes revisions to the error handling behavior that is defined
in the base BGP-4 specification (RFC4271). The motivation for changes to this
behaviour is to avoid a single erroneous UPDATE message (or attribute within
such a message) impacting an entire BGP-4 session (and hence all the NLRI that
it carries). The document introduces the "treat-as-withdraw" mechanism, which
treats the NLRI received within an erroneous UPDATE message as though they are
withdrawn by the remote neighbor. Additionally an "attribute discard" approach
is introduced. The document evaluates the existing BGP-4 attributes and defines
new error handling behaviours for them. Errors for which the existing BGP-4
error handling behaviour is to be retained are also considered.

There is working group consensus amongst both network operators, and BGP-4
implementors that this mechanism is a useful Standards Track document to
improve the robustness of the BGP-4 protocol, whilst also considering the
correctness of routing information it carries.

2. Review and Consensus

There has been significant debate relating to the balance of different
functionalities required between working group participants which seek to
maintain established sessions (or retain NLRI during their failure), and those
that consider the correctness of the protocol paramount. The document's
intention was originally to address a point failure scenario observed within
the Internet related to optional transitive attributes, but based on wider
operational experience, the working group has extended the scope of the

The behaviours now included within the document have been subject to
significant review over multiple cycles from both protocol experts, network
operators, and protocol implementors contributing to the balance between
approaches having been reached.

Operational requirements for the changes within the document have been
discussed at length - and reviewed with GROW. Whilst there is some appetite for
additional mechanisms for operators to maintain the integrity of their networks
by compromising correctness of the routing information in their network -
especially during catastrophic failures - this document does not reflect these
additional requirements - which are subject to separate proposals to the
working group.

Significant deployment experience has been gained for the changes described in
the document. The shepherd is aware of four shipping commercial implementations
of BGP-4 (Alcatel-Lucent SR OS, Cisco IOS, Cisco IOS XR, Juniper JUNOS), and
one open source implementation (Quagga) have implemented the behaviours
described in the document. The feedback from these implementations has helped
to iterate the contents of the document, and reach consensus within the working

3. Intellectual Property

There have been no IPR disclosures on this document, or its predecessors
(draft-scudder-idr-optional-transitive, draft-chen-ebgp-error-handling).

[TBD: binal pole pending.

4. Other Points

There are no downrefs for this document.

There are no requests on IANA that need consideration.