Subject: [Idr] [Errata Held for Document Update] RFC4271 (6498)

From: RFC Errata System <[email-masked]>
Date: Mon, 29 Mar 2021 10:30:14 -0700 (PDT)

The following errata report has been held for document update 
for RFC4271, "A Border Gateway Protocol 4 (BGP-4)". 

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You may review the report below and at:
https://www.rfc-editor.org/errata/eid6498

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Status: Held for Document Update
Type: Technical

Reported by: Graham Paasch <[email-masked]>
Date Reported: 2021-03-27
Held by: Alvaro Retana (IESG)

Section: 5.1.5

Original Text
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LOCAL_PREF is a well-known attribute that SHALL be included in all UPDATE messages that a given BGP speaker sends to other internal peers. 

Corrected Text
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LOCAL_PREF is a well-known discretionary attribute that SHALL be included in all UPDATE messages that a given BGP speaker sends to other internal peers. 

Notes
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It is unclear from the text to which of the four path attribute categories LOCAL_PREF belongs. There was even submitted an errata to create a fifth category for this attribute, but it is clear from the definition of the categories, that this attribute is well known discretionary. All routers must be capable of sending or receiving the LOCAL_PREF attribute, however it is up to a routers discretion whether to include that attribute in an UPDATE message.

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[Verifier notes.]

This is a valid report.  The terminology in rfc4271 is not ideal, so using "discretionary" with a required action can cause significant confusion, even if that is the correct term for this attribute.  A future version of this RFC should consider updating/cleaning up the terminology.

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RFC4271 (draft-ietf-idr-bgp4-26)
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Title               : A Border Gateway Protocol 4 (BGP-4)
Publication Date    : January 2006
Author(s)           : Y. Rekhter, Ed., T. Li, Ed., S. Hares, Ed.
Category            : DRAFT STANDARD
Source              : Inter-Domain Routing
Area                : Routing
Stream              : IETF
Verifying Party     : IESG