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Wont reregister while TCP retransmissions. - Printable Version

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Wont reregister while TCP retransmissions. - btu00 - 08-26-2014 10:22 AM


I have a T41P handset. Whist it is all working there is no problem, However if I break the link to the internet on my router and reconnect it then the TP41 will not reregister for about 15 minutes.

So a wireshark trace shows that the SIP message (I have seen it happen on a sip register and a sip subscribe) starts a TCP retransmission of the packet. (because the wan was broken and no reply was received) . This retransmission happens quickly at first and then slows to about once ever 30 seconds. Other NTP and DNS functions continue to happen around this but no further SIP happens until the TCP retransmission stop, why they stop I do not know, timer expiry or count expiry?? but it takes 12 to 15 minutes then SIP register will happen again and all is ok.

Any Ideas please?


RE: Wont reregister while TCP retransmissions. - Yealink Support - 08-26-2014 02:03 PM

Hi Btu00,

What you mentioned is that,when you reboot the router in your side(so that the wan is broken,then reconnect),the phone would send a lot of TCP retransmissions,during that period,the phone will not register.
I have one doubt that ,in your scenario,the status of the account is from registered to deregistered,and after 15 minutes,the phone is register again ? or,when you break the wan,then you just start to register the account ,and find out that it cannot be registered?

RE: Wont reregister while TCP retransmissions. - btu00 - 08-26-2014 07:07 PM


It looks like the router is resetting the state full firewall table when the wan drops. The result is when the wan restores the tcp retransmission is seen as a invalid packet( not part of an established flow). Problem is only on tcp, udp is ok.

Also if I alter any account settings on the t41p it restarts the register process. GDP syn etc and this immediately works ok. Is there a setting I can alter to reduce the time taken to timeout a failed tcp flow?


RE: Wont reregister while TCP retransmissions. - Coco_Yealink - 09-01-2014 10:38 AM

Hi btu00,

Please try to reduce the value of below setting in the web interface:
Account-Advanced-SIP Registration Retry Timer(0~1800s).
And to see whether the issue will be fixed or not.

[Image: attachment.php?aid=973]

RE: Wont reregister while TCP retransmissions. - JMComstock - 11-19-2015 07:55 AM


I have this same issue and changing the SIP setting, as suggested, does not remedy the problem. You are correct that the router/firewall resets the NAT translations under certain circumstances such as a reboot.

In the log, level 6, the REGISTER attempts to go out and it knows there is an error, but it does not seem willing to reset the socket connection for about 10-15 minutes.

As follows:

Nov 18 22:11:26 SIP [464]: SDL <6+info > [000] REGISTER SIP/2.0^M

Nov 18 22:11:27 SIP [464]: SDL <6+info > [000] Cannot connect socket node / select timeout (1000 ms)
Nov 18 22:11:27 SIP [464]: SDL <6+info > [000] socket node:, socket 15 [pos=0], in progress
Nov 18 22:11:58 SIP [463]: SUA <6+info > [000] App event:[0x8000000a] wParam:(0x0000),lParam:(0x0000) SIP_MSG_UPDATE_ECORE_EVENT
Nov 18 22:11:58 SIP [463]: SUA <6+info > [000] Emb event:[0x00000002] recv
Nov 18 22:11:58 SIP [463]: SUA <3+error > [000] [Server0]: try reg again after (30) s

It tries this over and over for about 10 to 15 minutes.

But it is not until it finally decides to read the socket that it figures out the SOCKET is dead:

Nov 18 22:13:00 SIP [463]: SUA <3+error > [000] [Server0]: try reg again after (30) s

Nov 18 22:13:18 SIP [464]: SDL <3+error > [000] Could not read socket - close it

At that point it re-registers correctly.

Can you see if the developers can close the TCP socket after the first reg failure?

Thanks in advance.