Hello Harshith, Generally, the implementation of size headers in a protocol is present to help in message delineation. In the case of SIP though, message delineation is handled by a blank line at the end of the message consisting of a "\r\n" string. Because of this, message size headers are not required, nor are they defined. That said, a Content-Length header is present because the body of a SIP message could have blank lines including any number of consecutive "\r\n" strings, so the Content-Length header allows a SIP implementation to ignore the next Content-Length bytes of the SIP message before looking for his "\r\n" sequence that states that the full SIP message has been concluded.
In some cases, you can look at the transport protocol's length/size parameter to figure out the size of a SIP message, but this isn't a very reliable method. In the case of UDP, the message might be fragmented over multiple UDP packets, and in the case of TCP/IP, one TCP datagram could contain more than 1 SIP message. Joel Gerber Network Operations Specialist - Telephone Telephone Eastlink [email protected] T: 519.786.1241 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Harshith Mulky Sent: April-20-16 6:16 AM To: [email protected] Subject: [Sip-implementors] Calculating SIP PDU Size Hi, Is there a way to calculate a SIP PDU Message Size? In wireshark, I am able to see total Bytes sent over the wire and I can only see the Content-Length of a SDP message in Application layer How do i calculate the PDU for SIP for a INVITE message like this? INVITE sip:[email protected]:5060 SIP/2.0 Via:SIP/2.0/UDP 64.215.212.60;branch=z9hG4bK-BroadWorks.as1-122.166.57.88V5060-0-602827015-633237880-1253188620813- From:"1st user1"<sip:[email protected];user=phone>;tag=633237880-1253188620813- To:"3rd ont3"<sip:[email protected]> Call-ID:[email protected] CSeq:602827015 INVITE Contact:<sip:as.iop2.broadworks.net> Supported:100rel Allow:ACK,BYE,CANCEL,INVITE,OPTIONS,PRACK,REFER,NOTIFY,UPDATE,INFO Accept:application/sdp,multipart/mixed Max-Forwards:70 Content-Type:application/sdp Content-Length:194 v=0 o=BroadWorks 197190 1 IN IP4 64.215.212.60 s=- c=IN IP4 64.215.212.60 t=0 0 m=audio 5004 RTP/AVP 0 97 a=sendrecv a=rtpmap:0 PCMU/8000/1 a=rtpmap:97 telephone-event/8000 a=ptime:10 Please let me know of some ideas Thanks Harshith _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
