I have a PCAP for a SIP session that has the relative sequence number start at 1509 and then after 6 packets it restarts at zero and then subsequently thinking that everything afterwards is out of sequence. What is value "SET" mean in the Marker column? I see it as set to True in the Packet detail screen in the Marker parameter field. Normally this occurs at the very beginning of the session. Thanks for your help. Eric asked 24 Sep '12, 14:21  EricKnaus |
One Answer:
The Command Sequence number should be increasing in a SIP dialog, so it shouldn't reset, other than after an unregister I suppose. As for "Set" in the marker column that's probably an RTP question. The meaning of the mark bit is defined through RTP profiles. For speech related streams it can mean resumption of speech after silence suppression in G.729B or VAD/CNG in addition to G.711. For video streams it can mark the start of a new video frame. answered 25 Sep '12, 06:43  Jaap ♦ |
