[OpenSER-Devel] Possible bug in the tm module in the presence of packet loss/branches

[Bogdan-Andrei Iancu]

Hi Maxim,

I was also digging through Figure 5 , but it seams strange to me that 
the UAC cancel scenario is not included in that diagram.

Regards,
Bogdan

Maxim Sobolev wrote:
> Dan Pascu wrote:
>> My issue with what you're proposing is that it tries to modify the 
>> SIP callflow to something no specified in the RFC, to solve a non-SIP 
>> problem. I also do not like the idea that the proxy would keep 
>> retransmitting on a branch after the originator has canceled the call.
>
> Well, the problem is that while it's not specified directly in the 
> RFC, but the current UAC behavior clearly violates 3-way handshake 
> mechanism and leaves window open for UAC is UAS ending up in disjoint 
> states due to 100 Trying loss. We can argue how big that window is 
> (for example on some of my servers I can see about 0.1% of UDP being 
> dropped), but the fact remains.
>
> If you look at the Figure 5 in the RFC 3261 the only way client 
> transaction could move directly from the Calling state to the 
> Terminated state is via Timer B or Transport Err. No other path exist.
>
> Regards,