[asterisk-users] SendText causes Retransmission errors

[Kevin P. Fleming]

On 03/18/2012 08:07 PM, Matt Hamilton wrote:
> Kevin,thanks for your response.
>
> Here is the more detailed Wireshark capture of the SIP traffic between
> phone (10.0.1.57) and Asterisk (10.0.1.103). The numbers between
> parentheses are Request Frames. I don't see an ACK for the 200 OK to the
> INVITE (491) for the dialplan that gives us Retransmission errors
> (without WAIT), but there is also no ACK for the same INVITE for the
> dialplan that works (with WAIT).

> If you still want to take a look at the full packet capture, I'll post it.
>
> Matt
>
> ---------------------------------------------------------------------------------------------
>
> Without WAIT(1) - we get Retransmisson errors
>
> 486 10.0.1.57 10.0.1.103 Request: INVITE sip:8*104_line104 at 10.0.1.103,
> with SDP
> 487 10.0.1.103 10.0.1.57 Status: 401 Unauthorized
> 490 (486) 10.0.1.57 10.0.1.103 Request: ACK sip:8*104_line104 at 10.0.1.103
> 491 10.0.1.57 10.0.1.103 Request: INVITE sip:8*104_line104 at 10.0.1.103,
> with SDP
> 492 10.0.1.103 10.0.1.57 Status: 100 Trying
> 493 10.0.1.103 10.0.1.57 Request: MESSAGE sip:104 at 10.0.1.57:5060
> (text/plain)
> *500 (for 491) 10.0.1.103 10.0.1.57 Status: 200 OK, with SDP*
> 501 10.0.1.103 10.0.1.57 Request: NOTIFY sip:104 at 10.0.1.57:5060
> 502 10.0.1.103 10.0.1.57 Request: CANCEL sip:104 at 10.0.1.57:5060

Why did Asterisk CANCEL the call here?

> *503 (for 493) 10.0.1.57 10.0.1.103 Status: 200 OK*
> 524 (503) 10.0.1.57 10.0.1.103 Request: ACK
> sip:8*104_line104 at 10.0.1.103:5060

This appears to be broken. The listing here claims this ACK is in 
response to the '200 OK' in packet 503, which itself was a final 
response to the MESSAGE request in packet 493. However, MESSAGE requests 
do not use ACK for a three-way handshake like INVITE requests do. In 
addition, this packet is going the wrong direction to be an ACK for 
packet 503, since it's going the same direction as packet 503 did.

Whatever method you used to generate this report seems to be broken. I 
can't tell you exactly how it is broken without seeing the headers in 
the messages, though.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at www.digium.com & www.asterisk.org