[rohc] P-Headers in the static SIP/SDP compression dictionary
Carsten Bormann <cabo@tzi.org> Tue, 16 July 2002 02:46 UTC
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Date: Tue, 16 Jul 2002 04:38:32 +0200
From: Carsten Bormann <cabo@tzi.org>
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Subject: [rohc] P-Headers in the static SIP/SDP compression dictionary
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In preparing draft-ietf-sipping-sigcomp-sip-dictionary-03.txt, there has been some discussion about the best way to handle P-headers. Obviously, P-headers are private, so maybe they should not be part of a static SIP dictionary that all SIP implementations that support compressed signaling have to use. On the other hand, P-headers are likely to be present in many messages exchanged over low-bandwidth cellular links. Not supporting them in the static dictionary increases the size of these messages. So what should we do for -04? Here is a proposal for a compromise position. Instead of bloating the dictionary by including every P-header in sight, we could collect a set of strings likely to turn up in P-headers. Here is my provisional list: [CRLF]P- Access- Associated- Called- Charging- Function- Party- Visited- Network- Adresses:[SP] URI:[SP] ID:[SP] Info:[SP] Vector:[SP] This means that your typical P-header will need 3 to 4 dictionary references instead of one if we just pasted all of them in. This may (depending on the compression algorithm) still be a sizable win. The dictionary size will only increase moderately, in particular since some of these strings are already present in the dictionary. Comments? WG meetings where this could turn up: ROHC, Wed 0900-1130, Room 502 SIP, Wed 1300-1500, Room 301/302 Gruesse, Carsten _______________________________________________ Rohc mailing list Rohc@ietf.org https://www1.ietf.org/mailman/listinfo/rohc
- [rohc] P-Headers in the static SIP/SDP compressio… Carsten Bormann