[Serusers] Can SER 2.0.0-rc1 pstn.cfg file actually work with BYE from PSTN?

Frank Durda IV frank.durda at hypercube-llc.com
Mon Oct 5 21:16:20 CEST 2009


Well, I thought this was working, but after more testing, it is
still exhibiting the problem I had before.   (Some hard-coded
routing I put in was concealing the fact that it isn't
handling this situation when left on its own.)

In the PSTN gateway model, SER still doesn't know how to cope
when a BYE or re-INVITE arrives which has come from the PSTN
gateway, and at best it makes a guess as to which is the right
destination for the messages.  (It usually ends up looping
back to itself.)  In this case with the packets that are
being received, the pstn.cfg example from the documentation
doesn't do the right thing, because loose_route() doesn't get
triggered for the BYE and re-INVITE messages, so SER is on
its own to determine where to forward the messages.

Here is a full example of the messages involved.   In my
earlier word example I said the original call INVITE could
come from four IP addresses, but in real life the number
is more like 200 sources.  It is still the same problem,
be it two source addresses or a million.  Which address
to choose in this situation?

Almost everything is correctly-relayed back to the correct IP
address (66.77.88.99), EXECPT a BYE initiated by the called
network (shown), or a re-INVITE initiated by the called network
(not shown, but requires the same handling as called-network
BYE).   If one can be cured, both should start working.

Key addresses in the example:
Call initiates via asterisk server at 66.77.88.99  CALL SOURCE
SER is 206.33.44.55
PSTN gateway switch is 10.100.20.30  (where BYE comes from)
2.0.0-rc1 (x86_64/freebsd)

I have only included the messages between the SER and PSTN gateway
switch, as that is where the trouble starts.  If the others are
needed, I can get them.


U 2009/10/05 17:44:48.002403 206.33.44.55:5060 -> 10.100.20.30:5060
INVITE sip:9615551212 at 10.100.20.30 SIP/2.0
Record-Route: <sip:206.33.44.55;ftag=as33ea0360;lr=on>
Via: SIP/2.0/UDP 
206.33.44.55;branch=z9hG4bK17e4.1b3604dc0be3614c8a5ba10b15c5c39
b.0
Via: SIP/2.0/UDP 66.77.88.99:5060;branch=z9hG4bK32448737;rport=5060
From: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
To: <sip:9615551212 at 206.33.44.55>
Contact: <sip:3796661000 at 206.33.44.55:5060>
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
CSeq: 102 INVITE
User-Agent: Asterisk PBX
Max-Forwards: 16
Date: Mon, 05 Oct 2009 17:44:47 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY
Supported: replaces
Content-Type: application/sdp
Content-Length: 435

o=root 27275 27275 IN IP4 206.33.44.66
s=session
c=IN IP4 206.33.44.66
t=0 0
m=audio 20366 RTP/AVP 0 3 8 112 5 10 7 97 111
a=rtpmap:0 PCMU/8000
a=rtpmap:3 GSM/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:112 AAL2-G726-32/8000
a=rtpmap:5 DVI4/8000
a=rtpmap:10 L16/8000
a=rtpmap:7 LPC/8000
a=rtpmap:97 iLBC/8000
a=fmtp:97 mode=30
a=rtpmap:111 G726-32/8000
a=silenceSupp:off - - - -
a=ptime:20
a=sendrecv
a=nortpproxy:yes


U 2009/10/05 17:44:48.004815 10.100.20.30:5060 -> 206.33.44.55:5060
SIP/2.0 100 Trying
Record-Route: <sip:206.33.44.55;ftag=as33ea0360;lr=on>
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
CSeq: 102 INVITE
From: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
To: <sip:9615551212 at 206.33.44.55>;tag=000a0283+1+68bb002b+5fee0f2
Via: SIP/2.0/UDP 
206.33.44.55;branch=z9hG4bK17e4.1b3604dc0be3614c8a5ba10b15c5c39
b.0
Via: SIP/2.0/UDP 66.77.88.99:5060;branch=z9hG4bK32448737;rport=5060
Server: DC-SIP/2.0
Supported: timer
Content-Length: 0


U 2009/10/05 17:44:53.956206 10.100.20.30:5060 -> 206.33.44.55:5060
SIP/2.0 183 Session Progress
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
CSeq: 102 INVITE
From: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
To: <sip:9615551212 at 206.33.44.55>;tag=000a0283+1+68bb002b+5fee0f2
Via: SIP/2.0/UDP 
206.33.44.55;branch=z9hG4bK17e4.1b3604dc0be3614c8a5ba10b15c5c39
b.0
Via: SIP/2.0/UDP 66.77.88.99:5060;branch=z9hG4bK32448737;rport=5060
Server: DC-SIP/2.0
Supported: timer
Record-Route: <sip:206.33.44.55;ftag=as33ea0360;lr=on>
Contact: <sip:9615551212 at 10.100.20.30>
Content-Type: application/sdp
Content-Length: 173

v=0
o=- 3463753493 3463753549 IN IP4 10.100.20.30
s=-
c=IN IP4 206.33.99.0
t=0 0
m=audio 34530 RTP/AVP 0
a=sendrecv
a=ptime:20
a=rtpmap:0 PCMU/8000
a=silenceSupp:off - - - -


U 2009/10/05 17:44:54.855199 10.100.20.30:5060 -> 206.33.44.55:5060
SIP/2.0 183 Session Progress
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
CSeq: 102 INVITE
From: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
To: <sip:9615551212 at 206.33.44.55>;tag=000a0283+1+68bb002b+5fee0f2
Via: SIP/2.0/UDP 
206.33.44.55;branch=z9hG4bK17e4.1b3604dc0be3614c8a5ba10b15c5c39
b.0
Via: SIP/2.0/UDP 66.77.88.99:5060;branch=z9hG4bK32448737;rport=5060
Server: DC-SIP/2.0
Supported: timer
Record-Route: <sip:206.33.44.55;ftag=as33ea0360;lr=on>
Contact: <sip:9615551212 at 10.100.20.30>
Content-Type: application/sdp
Content-Length: 173

v=0
o=- 3463753493 3463753549 IN IP4 10.100.20.30
s=-
c=IN IP4 206.33.99.0
t=0 0
m=audio 34530 RTP/AVP 0
a=sendrecv
a=ptime:20
a=rtpmap:0 PCMU/8000
a=silenceSupp:off - - - -


U 2009/10/05 17:44:57.125294 10.100.20.30:5060 -> 206.33.44.55:5060
SIP/2.0 200 OK
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
CSeq: 102 INVITE
From: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
To: <sip:9615551212 at 206.33.44.55>;tag=000a0283+1+68bb002b+5fee0f2
Via: SIP/2.0/UDP 
206.33.44.55;branch=z9hG4bK17e4.1b3604dc0be3614c8a5ba10b15c5c39
b.0
Via: SIP/2.0/UDP 66.77.88.99:5060;branch=z9hG4bK32448737;rport=5060
Server: DC-SIP/2.0
Supported: timer
Record-Route: <sip:206.33.44.55;ftag=as33ea0360;lr=on>
Contact: <sip:9615551212 at 10.100.20.30>
Content-Type: application/sdp
Content-Length: 173

v=0
o=- 3463753493 3463753549 IN IP4 10.100.20.30
s=-
c=IN IP4 206.33.99.0
t=0 0
m=audio 34530 RTP/AVP 0
a=sendrecv
a=ptime:20
a=rtpmap:0 PCMU/8000
a=silenceSupp:off - - - -


U 2009/10/05 17:44:57.187498 206.33.44.55:5060 -> 10.100.20.30:5060
ACK sip:9615551212 at 10.100.20.30:5060 SIP/2.0
Record-Route: <sip:206.33.44.55;ftag=as33ea0360;lr=on>
Via: SIP/2.0/UDP 
206.33.44.55;branch=z9hG4bK17e4.cb89b9e25754fc653a32363a1ba12e5
9.0
Via: SIP/2.0/UDP 66.77.88.99:5060;branch=z9hG4bK6a6bf681;rport=5060
From: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
To: <sip:9615551212 at 206.33.44.55>;tag=000a0283+1+68bb002b+5fee0f2
Contact: <sip:3796661000 at 206.33.44.55:5060>
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
CSeq: 102 ACK
User-Agent: Asterisk PBX
Max-Forwards: 16
Content-Length: 0

So far, everything has worked fine.

And now, the called party hangs up first, so the PSTN switch
send a BYE back to SER (because of the Record-Route used in
the INVITE).  If the Record-Route was absent, the PSTN switch
tries to send the BYE direct to 66.77.88.99 (asterisk server),
cutting SER out of the loop entirely and leaving the rtpproxy
for that call running for a while.


U 2009/10/05 17:45:07.356019 10.100.20.30:5060 -> 206.33.44.55:5060
BYE sip:3796661000 at 206.33.44.55:5060 SIP/2.0
Via: SIP/2.0/UDP 
10.100.20.30;branch=z9hG4bK+ffc8b51a07f0b4336d0443eee0ed0b5e+00
0a0283+1
Max-Forwards: 70
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
From: <sip:9615551212 at 206.33.44.55>;tag=000a0283+1+68bb002b+5fee0f2
To: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
CSeq: 920677113 BYE
Route: <sip:206.33.44.55;ftag=as33ea0360;lr=on>
Supported: timer
Content-Length: 0


So now SER has the BYE but SER doesn't know who to send it on
to - loose_route() isn't triggered.  So the BYE gets sent to the
wrong place, no response, PSTN switch repeats BYE several times
before SER tells it to stop.  The place SER should send the
message (66.77.88.99) is in the To: header, but nowhere else,
and apparently isn't holding onto such details from the
earlier messages.


U 2009/10/05 17:45:07.905334 10.100.20.30:5060 -> 206.33.44.55:5060
BYE sip:3796661000 at 206.33.44.55:5060 SIP/2.0
Via: SIP/2.0/UDP 
10.100.20.30;branch=z9hG4bK+ffc8b51a07f0b4336d0443eee0ed0b5e+00
0a0283+1
Max-Forwards: 70
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
From: <sip:9615551212 at 206.33.44.55>;tag=000a0283+1+68bb002b+5fee0f2
To: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
CSeq: 920677113 BYE
Route: <sip:206.33.44.55;ftag=as33ea0360;lr=on>
Supported: timer
Content-Length: 0

...


U 2009/10/05 17:45:35.038148 10.100.20.30:5060 -> 206.33.44.55:5060
BYE sip:3796661000 at 206.33.44.55:5060 SIP/2.0
Via: SIP/2.0/UDP 
10.100.20.30;branch=z9hG4bK+ffc8b51a07f0b4336d0443eee0ed0b5e+00
0a0283+1
Max-Forwards: 70
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
From: <sip:9615551212 at 206.33.44.55>;tag=000a0283+1+68bb002b+5fee0f2
To: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
CSeq: 920677113 BYE
Route: <sip:206.33.44.55;ftag=as33ea0360;lr=on>
Supported: timer
Content-Length: 0



U 2009/10/05 17:45:37.354456 206.33.44.55:5060 -> 10.100.20.30:5060
SIP/2.0 408 Request Timeout
Via: SIP/2.0/UDP 
10.100.20.30;branch=z9hG4bK+ffc8b51a07f0b4336d0443eee0ed0b5e+00
0a0283+1
Call-ID: 23cfb70d5362a5180aeb5048470591fc at 66.77.88.99
From: <sip:9615551212 at 206.33.44.55>;tag=000a0283+1+68bb002b+5fee0f2
To: "TROUBLESHOOTING 1000" <sip:3796661000 at 66.77.88.99>;tag=as33ea0360
CSeq: 920677113 BYE
Server: SER (2.0.0-rc1 (x86_64/freebsd))
Content-Length: 0


route{
xlog("L_ERR", "MAIN ROUTE \n method:<%rm>   From URI:<%fu> From Tag:<%ft>
 Destination Set:<%ds>  Request's R-URI:<%ru> To URI:<%tu>  Received 
IP:<%Ri> So
urce IP:<%si> Source Port:<%sp> Call ID:<%ci>  Host's Hostname:<%Hn>  
Hosts Doma
inname:<%Hd>  Hosts FQDN <%Hf>  Hosts IP <%Hi>");

#       first do some initial sanity checks

        if (!mf_process_maxfwd_header("10")) {
                sl_reply("483","Too Many Hops");
                break;
        }

        if (msg:len >=  max_len ) {
                sl_reply("513", "Message too big");
                break;
        }

        if (loose_route()) {
                if (src_ip==10.100.20.30) {         #Is it outbound?
                        log(1, "Doing loose_route from PSTN\n");
                } else {
                        log(1, "Doing loose_route to PSTN\n");
                }

                t_relay();
                break;
        }

The rest of main is determining direction if there was
no loose_route() and here is where it suddenly needs
to be told where exactly the BYE message should be sent
because the correct destination is one of many possible
call sources.  Neither of the "Doing loose_route" messages
get displayed when the BYE is handled.

Thanks again for suggestions.



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