[SIPForum-discussion] Invalid SDP line (no '=' delimiter) error !

[Joel Gerber]

I'd have to look up RFC 3264/4566 to see if it is detailed there. I have never seen it in the wild so I assumed it was incorrect. Even if it is valid according to RFC, I believe some element in between your softphone and the SBC is having a hard time parsing some part of the m= line which is the source of your woes.


Joel Gerber
Network Operations Specialist - Telephone
Telephone
Eastlink
Joel.Gerber at corp.eastlink.ca<mailto:%20Joel.Gerber at corp.eastlink.ca>    T: 519.786.1241

From: Badri Ranganathan [mailto:badri at arcatech.com]
Sent: May-28-15 12:48 PM
To: Joel Gerber
Cc: discussion at sipforum.org
Subject: RE: Invalid SDP line (no '=' delimiter) error !

Thanks a lot for the reply joel !

The /1 is the "media port count" in SDP and even works in some of the SBC's like Ericsson SBC. It is not complaining. Only Sonus SBC has given me this problem.
Do you think this field is incorrect ? I have not looked in detail into the SDP, but in the code, I can see that /1 is being described as "media port count"

Thanks,
Badri.




From: Joel Gerber [mailto:Joel.Gerber at corp.eastlink.ca]
Sent: 28 May 2015 17:27
To: Badri Ranganathan
Cc: discussion at sipforum.org<mailto:discussion at sipforum.org>
Subject: RE: Invalid SDP line (no '=' delimiter) error !

>From a cursory glance, I would say the issue is caused from the source.

This is what is sent out:
m=audio 5000/1 RTP/AVP 8 101

The "/1" after the "m=audio 5000" is invalid as far as I know.

Not knowing where the ws_frame4 file was grabbed from makes it hard to describe what happened, but, I would say somewhere between the w_frame52 capture and the ws_frame4 capture there is a SIP ALG, Proxy, B2BUA, or some other sort of SIP device that had an issue parsing the originally sent SDP which caused its parsing engine to generate the messed up SDP body that is seen in the ws_frame4 packet capture file.

It's a perfect illustration of the old adage: "Garbage in, garbage out" :)

Joel Gerber
Network Operations Specialist - Telephone
Telephone
Eastlink
Joel.Gerber at corp.eastlink.ca<mailto:%20Joel.Gerber at corp.eastlink.ca>    T: 519.786.1241

From: discussion-bounces at sipforum.org<mailto:discussion-bounces at sipforum.org> [mailto:discussion-bounces at sipforum.org] On Behalf Of Badri Ranganathan
Sent: May-28-15 9:16 AM
To: discussion at sipforum.org<mailto:discussion at sipforum.org>
Subject: [SIPForum-discussion] Invalid SDP line (no '=' delimiter) error !

Hi all,

I am answering a SIP call made to my softphone. The softphone rings and also sends a 200 OK correctly. But the other end that made the call is seeing a failure in the SDP of the 200 OK packet.


This error is seen in SDP header => Invalid SDP line (no '=' delimiter) error

w.r.t w_frame4_public_ip.pcap It looks like the failure as seen in wireshark is because  line "audio 5000 RTP/AVP 8 101" should really be "m= audio 5000 RTP/AVP 8 101"
so it doesn't see the '=' delimiter.

But if you look at w_frame52_local_ip.pcap, the packets sent from the local IP has the contents correct.

It is only after passing the public IP and at the network premises, that this failure is reported by the Session Border controller.

I am not able to understand why a correctly formed packet sent out is seen "corrupted" at the network end.

Any ideas really appreciated.

Thanks,
Badri.
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