Subject: [rohc] Statefull SIGCOMP

From: kishore sowdi <[email-masked]>
Date: Wed, 6 Jun 2012 20:02:45 +0800 (SGT)

Hi,
 
I am using SIGCOMP to compress/decompress SIP application messages.

SIP Client is uploading UVDM bytecode in all messages it sends to server (Not stateful).

Message flow:
1) SIP REGISTER from Client to Server
2) 200 OK response from Server to Client for (1).

3) SIP SUBSCRIBE Client to server
4) 200 OK response from Server to Client for (3).

At (2). , SIP Client is stores the state after decompressing 200 OK response.
 (Pasting the packet sniffer(wireshark) logs .. ... shows 3 state create requests in "UDVM Execution Trace")

[-]UDVM execution trace
 no_of_state_create 3
 ### Creating state ###
 Partial state identifier: AEDBAB80652A
 ### Creating state ###
 Partial state identifier: AAA2B32CE212
 ### Creating state ###
 Partial state identifier: 
 
what does partial id signify here during state create ??...

Now, At (4),  Server references the state by giving partial state identifier. (please see below trace pasted)
But, this referred state identifier and state identifier of stored state duirng (2)  do not match. ...Should they match at first place?
Hence SIP Client fails to decompress (4) .

 [-]Signaling Compression
  Returned_feedback item: 03
  Partial state identifier: AEDBAB80652A
  Remaining SigComp message bytes: 280
  ### Accessing state ###
  Partial state identifier: AEDBAB80652A
 
There are two issues:

Issue 1:
In (1) and (2) , SIP client/Server upload UDVM bytecode.
In (3) SIP Client is not suppossed to upload byte code again.... But it is uploading UDVM bytecode with T-Bit set to 1.

Issue 2:
Decompression failure of (4), during state reference.
 
Please suggest solutions to the above issues. and is my understanding of stateful implementation correct?
 
Regards,
Kishore