[IPv6]Re: [Errata Held for Document Update] RFC4291 (6596)

[Mark Andrews <[e-mail]>]

This just makes invalid every parser that correctly accepts "::0:0:0:0:0:0:1” today.
Fix the broken parsers, don’t break the working parsers.  

Add a note like.

Note “::” can be used to “compress” just the leading or trailing 16 bits leading to valid
but unusual IPv6 addresses like “::0:0:0:0:0:0:0” and “0:0:0:0:0:0:0::”.

> On 27 Dec 2025, at 13:44, RFC Errata System <[e-mail]> wrote:
> 
> The following errata report has been held for document update 
> for RFC4291, "IP Version 6 Addressing Architecture". 
> 
> --------------------------------------
> You may review the report below and at:
> https://www.rfc-editor.org/errata/eid6596
> 
> --------------------------------------
> Status: Held for Document Update
> Type: Technical
> 
> Reported by: Martin D Kealey <[e-mail]>
> Date Reported: 2021-06-0
> Held by: Erik Kline (IESG)
> 
> Section: 2.2
> 
> Original Text
> -------------
>   2. Due to some methods of allocating certain styles of IPv6
>      addresses, it will be common for addresses to contain long strings
>      of zero bits.  In order to make writing addresses containing zero
>      bits easier, a special syntax is available to compress the zeros.
>      The use of "::" indicates one or more groups of 16 bits of zeros.
>      The "::" can only appear once in an address.  The "::" can also be
>      used to compress leading or trailing zeros in an address.
> 
> Corrected Text
> --------------
> EITHER
> 
>   2. Due to some methods of allocating certain styles of IPv6
>      addresses, it will be common for addresses to contain long strings
>      of zero bits.  In order to make writing addresses containing zero
>      bits easier, a special syntax is available to compress the zeros.
>      The use of "::" indicates one or more "0" pieces, or two or more when
>      leading or trailing. The "::" can only appear once in an address.
> 
> OR
> 
>   2. Due to some methods of allocating certain styles of IPv6
>      addresses, it will be common for addresses to contain long strings
>      of zero bits.  In order to make writing addresses containing zero
>      bits easier, a special syntax is available to compress the zeros.
>      The use of "::" indicates one or more pieces of 16 bits of zeros,
>      or two or more when leading or trailing. The "::" can only appear
>      once in an address.
> 
> 
> Notes
> -----
> 1. The existing wording would permit "::" to be used in leading or trailing position to compress a single 16-bit piece, leading to the conclusion that "::0:0:0:0:0:0:1" is a valid way to write the loopback address, with eight colons.
> 
> Many consumers of textual IPv6 addresses would reject this out of hand as "too many colons", and it seems questionable that such an interpretation was ever intended. Enforcing this on producers would improve interoperability.
> 
> 2. The preceding paragraphs defines "piece", but the undefined term "group" is used in this paragraph, so by changing that term I hope to clarify that this is a textual substitution, necessarily aligned to a multiple of 16 bits.
> 
> I am uncomfortable with the phrasing "pieces of 16 bits of zeros", but I offer it as a single-word change to effect my point (2); I leave it to the discretion of the editor which of my alternatives to adopt.
> 
> --->8 INT AD notes 8<---
> 
> Readers of this RFC and this erratum are directed to RFC 5952, specifically section 4.*.
> 
> --------------------------------------
> RFC4291 (draft-ietf-ipv6-addr-arch-v4-04)
> --------------------------------------
> Title               : IP Version 6 Addressing Architecture
> Publication Date    : February 2006
> Author(s)           : R. Hinden, S. Deering
> Category            : DRAFT STANDARD
> Source              : IP Version 6 Working Group
> Stream              : IETF
> Verifying Party     : IESG
> 
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Mark Andrews, ISC
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