R: [Serusers] Retransmission problem

[Zappasodi Daniele]

Many thanks for the reply, it is very useful but it contains bad news because, if is it possible, it is important for me to preserve the possibility to have the SIP proxy and SIP gateway in the same board. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

 

Some other clarification:

1. I have two ethernet interfaces, if I give different IP address to proxy and gateway, can I leave them on the same hardware? 

 

2. If I correctly understand the transaction creation in SER: SER absorbs the retransmission only if already exists a transaction for the original INVITE and SER creates a new transaction for an INVITE only when is invoked the t_relay. Consequently, If a retransmitted INVITE arrives when the elaboration of the original INVITE is still in progress, SER repeats all the elaboration also for the second INVITE.

Do you confirm my description?

I have built a function that in heavy load traffic condition could be slow (it does an external query, something similar to an exec) and it is important that I don't invoke it twice for the same INVITE, so I try to use t_newtran to anticipate the transaction creation before invoking this function.

However, as first step, I will remove the t_newtran, t_forward_nonack_uri and I try again.

 

Thanks again.

 

-----Messaggio originale-----
Da: Greger V. Teigre [mailto:greger at teigre.com]
Inviato: mercoledì 6 settembre 2006 9.19
A: Zappasodi Daniele
Cc: serusers at lists.iptel.org
Oggetto: Re: [Serusers] Retransmission problem


1. DON'T have UA2 and SER on the same server. You are very likely to get problems because SER sees it's own IP address in a message destined for UA2
2. Don't use t_newtran and t_forward_nonack_uri unless you know exactly what you do (and probably not then either)
3. When having problems like that, use a pretested Getting Started config fil ( http://iptel.org/ser/doc/gettingstarted). If you still have the problem, there is something external (like UA2 on same box as SER). Fix it and then compare the logic of your config file with the Getting Started reference config
g-)

Zappasodi Daniele wrote: 

Hello, 

I have a big problem with the retransmissions.

In my tests sometimes the retransmission handler doesn't seem to work properly and it resends the INVITE after receiving a final response. 

Moreover it doesn't respect the time-out (instead wait 1 second it resends the packet after few decimal), but this is a minor item.



An example:

INVITE sip:31203

From 32201



	UA1(32201)  ---> SER ---> UA2(31203)	

INVITE 	UA1 ---> SER ---> UA2	

Trying	UA1 <--- SER

183		UA1 <--- SER <--- UA2

480		UA1 <--- SER <--- UA2

ACK	 	UA1 ---> SER ---> UA2	

...

Other call.



After 0,5 msec SER sends again the first INVITE to UA2:

INVITE 		SER ---> UA2	

183			SER <--- UA2

etc.



In the attached zipped file there are the syslog, the ser config file (only the relevant parts) and the ethereal captures related to this example.





Some additional information:

SER version is 0.9.2, compiled for arm.

In my scenario SER and UA2 are on the same box.

In LAN_capture.cap file there is the message flow between UA1 and SER, in lo_capture.cap between SER and UA2. 



Can someone explain me this behaviour?

Maybe something wrong in my config file? Note that I use t_lookup_request, t_newtran, t_forward_nonack_uri in order to recognize retransmitted INVITE, could it be here the problem?



thanks

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