Subject: [Technical Errata Reported] RFC8028 (6035)

From: RFC Errata System <[email-masked]>
Date: Tue, 31 Mar 2020 19:25:11 -0700 (PDT)

The following errata report has been submitted for RFC8028,
"First-Hop Router Selection by Hosts in a Multi-Prefix Network".

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You may review the report below and at:
https://www.rfc-editor.org/errata/eid6035

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Type: Technical
Reported by: Fernando Gont <[email-masked]>

Section: 3.1

Original Text
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Corrected Text
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In the context of this document, it is clear that the prefix information becomes more associated with the sending router, than with the link as a whole. As such, the PIO lifetimes should be interpreted to indicate the view of the router sending the Router Advertisement, as opposed to absolute information about a prefix.

For example, if two routers (say, router A and Router B), advertise the prefix 2001:db8::/64 as:

* Router A:
A=1, L=1, PIO: 2001:db8::/64, Valid Lifetime=0, Preferred Lifetime=0

* Router B:
A=1, L=1, PIO: 2001:db8::/64, Valid Lifetime=X, Preferred Lifetime=Z

then, addresses should be configured/maintained with a Valid Lifetime of X, and a Preferred Lifetime of Z. Furthermore, the prefix should be considered on-link with a Valid Lifetime of X. And Router A should be employed as the preferred next hop for packets sourced from the prefix 2001:db8::/64, since it advertises the prefix with a non-zero Valid Lifetime and non-zero Preferred Lifetime (as opposed to Router B).

As long as one router on the local subnet considers a prefix to be Valid (and possibly Preferred), the prefix should be considered Valid (and Preferred, if applicable). Similarly, as long as one router on the local subnet considers the prefix to be on-link and/or usable for auto-configuration, the prefix should be considered as such.

Notes
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This is not a bug in RFC8028, but rather a clarification on what's likely a desired behavior. As such, and if considered appropriate, this errata is meant to be "held for document update".

i would like to thank Fred Baker and Brian Carpenter for taking the time to answer my questions on RF8028.

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RFC8028 (draft-ietf-6man-multi-homed-host-10)
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Title               : First-Hop Router Selection by Hosts in a Multi-Prefix Network
Publication Date    : November 2016
Author(s)           : F. Baker, B. Carpenter
Category            : PROPOSED STANDARD
Source              : IPv6 Maintenance
Area                : Internet
Stream              : IETF
Verifying Party     : IESG