Subject: [rohc] draft-ietf-rohc-sigcomp-impl-guide-10

From: Magnus Westerlund <[email-masked]>
Date: Thu, 18 Jan 2007 10:11:24 +0100

Hi,

For your information we are doing some tweaking of the SigComp 
implementors guide using RFC-editor notes in the process of resolving 
the discusses placed. Currently the below changes are proposed. If you 
have strong opinion about any of these please respond ASAP.

Cheers

Magnus

First page header:

NEW:

Updates: RFC 3320, RFC 3321, RFC 3485 (once approved)

Title:

OLD:

Implementer's Guide for SigComp

NEW:

Signaling Compression (SigComp) Corrections and Clarifications

Abstract:

OLD:
This document (if approved) clarifies and corrects text in the
following updated RFCs: RFC 3320, RFC 3321, RFC 3485.

NEW:
This document updates the following RFCs: RFC 3320, RFC 3321, RFC 3485.

Section 1:
OLD:

       "in section 3.4" refers to section 3.4 of this document
       "in section RFC-3320:3.4 refers to section 3.4 of RFC 3320 [1]

NEW:
       "in section 3.4" refers to section 3.4 of this document
       "in section RFC3320-3.4" refers to section 3.4 of RFC 3320 [1]

Section 2.1, First paragraph:

OLD:

   SigComp [1] states that the default Decompression Memory Size (DMS)
   is 2K. The UDVM memory size is defined in section RFC3320:7 to be
   (DMS - sizeof (sigcomp_msg)) for messages transported over UDP and
   (DMS / 2) for those transported over TCP.

NEW:

   SigComp [1] states that the default Decompression Memory Size (DMS)
   is 2K. The UDVM memory size is defined in section RFC3320-7 to be
   (DMS - sizeof (sigcomp_msg)) for messages transported over UDP and
   (DMS / 2) for those transported over TCP.

Section 12, final paragraph

OLD:
   These are seen to be relatively low cost bugs as only these 5 strings
   are affected and they are only affected under certain conditions.

NEW:
   This document does not correct the dictionary, as any changes to the
   dictionary itself would be non-backwards-compatible, and require all
   implementations to maintain two different copies of the dictionary.
   Such a cost is far too high for a bug that is trivial to work around
   and has negligible effect on compression ratios.  Instead, we point
   out the flaw so as to allow implementers to avoid any consequent
   problems.  Specifically: if the bytecodes sent to a remote endpoint
   contain instructions that load only a sub-portion of the SIP/SDP
   dictionary, then the input stream provided to those bytecodes cannot
   reference any of these five offsets in the offset table unless the
   corresponding string portion of the dictionary has also been loaded.
   For example, if bytecodes loaded only the first three priorities of
   the dictionary (both string and offset table), use of the offset for
   "send" (at 0x089d) would be valid; however, use of the offset for
   "phone" (at 0x00f2) would not.

Please replace all occurances of "Sigcomp" with "SigComp".

-- 

Magnus Westerlund

IETF Transport Area Director & TSVWG Chair
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