[Blink] no audio if multiple ip-addresses are active

Saúl Ibarra Corretgé saul at ag-projects.com
Wed Aug 11 09:29:52 CEST 2010


> Here's the differences I see between a working SIP/SDP connection with
> another client, and Blink:
> My vlan IP is, other IPs on interfaces are and
> For the initial invite, X is the other client, B is Blink:
> X: INVITE sip:918007475150 at;transport=udp SIP/2.0
> B: INVITE sip:918007475150 at SIP/2.0

The request line is fine.

> X: Via: SIP/2.0/UDP
> B: Via: SIP/2.0/UDP
> -- this is the first case of the wrong IP address. is
> actually the IP of a vmware interface that's not used for any normal
> traffic.

This is not right. Can you reproduce it always? If so, can you give me 
more details on your network setup so I can reproduce it?

> X: Contact:<sip:432 at;transport=udp>
> B: Contact:<sip:tjrkpxia at>
> -- this is the second incorrect address. is the IP of the
> default route interface. Also 432 is the extension of the client. I'm
> not sure what tjrkpxia is.

Blink currently sends all traffic through the default route, so this is 
expected. If your default route gos through that IP address, it will be 
the one chosen. There is no support for selecting other interfaces.

The contact username is correct, we use a random string so it doesn't 
collide if multiple SIP clients are used at the same time in the same 
machine. The AoR is specified in the REGISTER requests To header.

> Now in SDP:
> X: o=- 8 2 IN IP4
> B: o=- 3490461286 3490461286 IN IP4
> X: c=IN IP4
> B: c=IN IP4
> the a= lines also differ, but I doubt they'd matter.

Even if o and a lines are wrong audio would flow if c line is correct. 
It looks like here we have the same case as in the Contact header: the 
IP for the default route is being used, as expected.

> These both result in a TRYING, and then OK. The only difference in the
> OK is that the VIA sent to blink contains the address
> again:
> X: Via: SIP/2.0/UDP
> B: Via: SIP/2.0/UDP
> I'm not sure how this mailing list is with attachments, but I'll
> include a .txt of the working and non-working SIP connections from
> Wireshark. I deleted the Authorization: headers.

Thanks for sending the traces. Looks like the IP address in Via and 
a=rtcp lines is wrongly calculated. If you are able to reproduce this 
I'd be interested in knowing the details so this can be fixed.


Saúl Ibarra Corretgé
AG Projects

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