[Technical Errata Reported] RFC6724 (6971)

[RFC Errata System <[e-mail]>]

The following errata report has been submitted for RFC6724,
"Default Address Selection for Internet Protocol Version 6 (IPv6)".

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You may review the report below and at:
https://www.rfc-editor.org/errata/eid6971

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Type: Technical
Reported by: Brian Carpenter <[e-mail]>

Section: 2.2

Original Text
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We define the common prefix length CommonPrefixLen(S, D) of a source
address S and a destination address D as the length of the longest
prefix (looking at the most significant, or leftmost, bits) that the
two addresses have in common, up to the length of S's prefix (i.e.,
the portion of the address not including the interface ID).  For
example, CommonPrefixLen(fe80::1, fe80::2) is 64.

Corrected Text
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We define the common prefix length CommonPrefixLen(S, D) of a source
address S and a destination address D as the length of the longest
prefix (looking at the most significant, or leftmost, bits) that the
two addresses have in common, up to the length of S's prefix (i.e.,
for most IPv6 addresses,
the portion of the address not including the interface ID).  For
example, CommonPrefixLen(fe80::1, fe80::2) is 64. For two IPv4-mapped
addresses in ::ffff:0:0/96, CommonPrefixLen() may be up to 128.

Notes
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1) Not all IPv6 address formats have a well-defined interface index.
2) In particular, the original text is inapplicable to IPv4-mapped addresses.
3) N.B.: In practice it seems that some implementations simply do a longest match up to /128 and that works fine.

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RFC6724 (draft-ietf-6man-rfc3484bis-06)
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Title               : Default Address Selection for Internet Protocol Version 6 (IPv6)
Publication Date    : September 2012
Author(s)           : D. Thaler, Ed., R. Draves, A. Matsumoto, T. Chown
Category            : PROPOSED STANDARD
Source              : IPv6 Maintenance
Area                : Internet
Stream              : IETF
Verifying Party     : IESG