[RoHCv1.2.0] RoHC Packet Builders and Decoders

Asked by Orville Andrade on 2009-10-23

Hi All,

I find something erroneous in the way 'Generic Extension header List' field in the IR & IR-Dyn Compressed Headers is built for IPv4 Headers and RTP Headers.

Although RoHCv1.2.0 does not support List Compression at the moment for IPv4 extension headers and RTP CSRC list; in the case of IPv4 'Dynamic part' (Section 5.7.7.4 of RFC3095) & RTP 'Dynamic part' (Section5.7.7.6 of RFC3095) the 'Generic Extension Header List' field should be packed with 1byte of 'zero' as this field is mandatory and not optional. This is inferred from the packet notation guidelines provided in (Section 5.2 of RFC3095).

Without this single byte addition I think that the IR & IR-Dyn do not conform to completely to RFC3095. Is my understanding correct.

--
Regards,
Orville Andrade

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Last query:
2009-10-23
Last reply:
2009-11-14
Launchpad Janitor (janitor) said : #1

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

Open the question again because it requires further analysis from the ROHC Team.

Hi !

Again, you're right ;-) The clarification is in the RFC 4815 (the RFC3095 is not really clear on this):

5.1. CSRC List Items in RTP Dynamic Chain

   RFC 3095-Section 5.7.7.6 defines the static and dynamic parts of the
   RTP header. This section indicates a 'Generic CSRC list' field in
   the dynamic chain, which has a variable length (see RFC 3095-Section
   5.8.6). This field is always at least one octet in size, even if the
   list is empty (as opposed to the CSRC list in the uncompressed RTP
   header, which is not present when the RTP CC field is set to 0).

Thank you again for the bug report. Do you expect to submit a patch to solve this ?

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