H323 Call Failure

Answered Question
Jul 16th, 2009
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I have an issue making 2 or more calls within a short space of time between two phones, one native IP behind a CME running 7.0.0.1 and the other behind a 2811 router with a basic H323 voice gateway configuration. The (edited) configs for each end are attached.


The first call from one phone to the other (or using csim) goes through fine.


However, once the call is ended, if a subsequent call is made within a minute or two afterwards to the same phone (or a phone via the same destination gateway), the call fails and I get the following debug output from h225/h245.


*Jul 16 09:01:49.052: h323chan_chn_process_read_socket: fd=2 of type CONNECTED has data


*Jul 16 09:01:49.052: h323chan_recvdata: recv failure on fd=2: errno=254 errstr=Connection reset by peerh323chan_chn_close: Calls[1] Exist on socketfd=2 Owner[2]


*Jul 16 09:01:49.052: h323chan_close: TCP connection from fd=2 closed



Anybody have any ideas? I've run out and as I write this am seconds away from banging my head against my desk.




Correct Answer by Nicholas Matthews about 7 years 9 months ago

You may want to try this command on the routers:


voice service voip

h323

no h245 simultaneous-connection-handle


It sounds like there is a device in your network (read: firewall) that may be incorrectly handling the TCP requests between your routers.


My suspicion is if you put 'session protocol sip' on the dial peers this would work, since it would be UDP by default.


You may also want to try lowering the TCP timeouts for H323 and try taking the firewall out of the equation for testing purposes.



-nick


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Correct Answer
Nicholas Matthews Thu, 07/16/2009 - 08:39
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You may want to try this command on the routers:


voice service voip

h323

no h245 simultaneous-connection-handle


It sounds like there is a device in your network (read: firewall) that may be incorrectly handling the TCP requests between your routers.


My suspicion is if you put 'session protocol sip' on the dial peers this would work, since it would be UDP by default.


You may also want to try lowering the TCP timeouts for H323 and try taking the firewall out of the equation for testing purposes.



-nick


duncan_watson Thu, 07/16/2009 - 18:49
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Nick,


The 'session protocol sip' command fixed it. Many thanks.


If you have a second, could you please explain your above answer, 'since it would be UDP by default' in a little more detail?



Many thanks again,

Duncan


Nicholas Matthews Thu, 07/16/2009 - 19:32
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Hi Duncan,


H323 uses TCP port 1720.


SIP uses UDP and TCP port 5060.


By default on the gateway, it will use UDP for SIP.


I think your problem was TCP socket related, so using SIP because it is UDP would probably fix the problem. Technically, you're hiding it, but it's up to you whether or not you would like to track down the problem.



Glad I could help.


-nick

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