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SRP527W-U trouble sending fax

paolo liberati
Level 1
Level 1

hi,

we have problem sending faxes with router SRP527W-U firmware 1.2.4 (003).

We found a strange behavior of the router when the  destination media gateway send two closer reinvite packets with two different media ports.

To be more clear I am going to make an example:

The srp527W-U start the sip dialog with the destination media gateway. The media gateway send  the first reinvite which is telling to the sr527w-u that its media port will be the 15868 port udp. The srp527w-u answer  with a 200 ok packet.

After the first 200 ok packet the destination  media gateway decide to change it's media port and send another reinvite  telling to the srp527-w-u that it will change its media port to 15870.

Srp527w-u  answer with another 200 ok packet but it doesn't change the destination  media port and the fax fail after some seconds (about 30 seconds).

After the second 200 ok the srp527w-u should change the destination port and start to send DCS (T.38) packet to the destination media gateway but instead start to send packet to the old media port so that's why the fax at the end fail.

We don't have problem sending faxes with SPA2102 firmware 5.2.12 using the same destination media gateway.

We have applied the same configuration of the SRP527W-U to the SPA2102 but with SPA2102 everything it's working fine.

I have done a couple of trace where it is possible to see what i am telling you (if someone of cisco need this traces i can send it via private message).

I hope that someone of the support staff can troubleshoot this behavior.

thanks in advance for your answer.

1 Reply 1

paolo liberati
Level 1
Level 1

here the trace i have done in LAB:

|Time     | aaa.bbb.ccc.130 (SRP527W-U)| aaa.bbb.ccc.17|||| aaa.bbb.ccc.19|                  

|0.000    |INVITE SDP (g729) ||SIP From: 0211111111 <>0211111111@sip.example.com To:<>0222222222@sip.example.com

|         |(5061)   ------------------>  (5060)   |                   |

|0.002    |         100 Trying|                   |                   |SIP Status

|         |(5061)   <------------------  (5060)   |                   |

|0.147    |         RTP (g729)                    |                   |RTP Num packets:1  Duration:0.000s SSRC:0x69AE7E33

|         |(16460)  <--------------------------------------  (15862)  |

|4.699    |         183 SDP (g729)                |                   |SIP Status

|         |(5061)   <------------------  (5060)   |                   |

|4.737    |         200 OK SDP (g729)               |                   |SIP Status

|         |(5061)   <------------------  (5060)   |                   |

|4.780    |         ACK       |                   |                   |SIP Request

|         |(5061)   ------------------>  (5060)   |                   |

|4.789    |         RTP (g729)                    |                   |RTP Num packets:1  Duration:0.000s SSRC:0x3ADB2A29

|         |(16460)  -------------------------------------->  (15862)  |

|6.973    |         RTP (g711A)                   |                   |RTP Num packets:1  Duration:0.000s SSRC:0x69AE7E33

|         |(16460)  <--------------------------------------  (15862)  |

|9.259    |         INVITE SDP (t38)              |                   |SIP Request

|         |(5061)   <------------------  (5060)   |                   |FIRST REINVITE PORT DECLARATION 15868

|9.319    |         200 OK SDP (t38)              |                   |SIP Status

|         |(5061)   ------------------>  (5060)   |                   |

|9.321    |         ACK       |                   |                   |SIP Request

|         |(5061)   <------------------  (5060)   |                   |

|9.375    |         INVITE SDP (t38)              |                   |SIP Request

|         |(5061)   <------------------  (5060)   |                   |SECOND REINVITE PORT DECLARATION 15870

|9.428    |         200 OK SDP (t38)              |                   |SIP Status

|         |(5061)   ------------------>  (5060)   |                   |

|9.431    |         ACK       |                   |                   |SIP Request

|         |(5061)   <------------------  (5060)   |                   |

|9.457    |         no-signal |                   |                   |t38:t30 Ind:no-signal

|         |(16460)  -------------------------------------->  (15868)  |

|9.793    |         v21-preamble                  |                   |t38:t30 Ind:v21-preamble

|         |(16460)  <--------------------------------------  (15870)  |

|11.269   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  <--------------------------------------  (15870)  |

|11.539   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  <--------------------------------------  (15870)  |

|11.588   |         no-signal |                   |                   |t38:t30 Ind:no-signal

|         |(16460)  <--------------------------------------  (15870)  |

|14.309   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  -------------------------------------->  (15868)  |

|14.628   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  -------------------------------------->  (15868)  |

|14.668   |         no-signal |                   |                   |t38:t30 Ind:no-signal

|         |(16460)  -------------------------------------->  (15868)  |

|14.948   |         v17-14400-long-training       |                   |t38:t30 Ind:v17-14400-long-training

|         |(16460)  -------------------------------------->  (15868)  |

|16.719   |         v21-preamble                  |                   |t38:t30 Ind:v21-preamble

|         |(16460)  <--------------------------------------  (15870)  |

|18.610   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  <--------------------------------------  (15870)  |

|18.880   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  <--------------------------------------  (15870)  |

|18.930   |         no-signal |                   |                   |t38:t30 Ind:no-signal

|         |(16460)  <--------------------------------------  (15870)  |

|21.468   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  -------------------------------------->  (15868)  |

|21.788   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  -------------------------------------->  (15868)  |

|21.828   |         no-signal |                   |                   |t38:t30 Ind:no-signal

|         |(16460)  -------------------------------------->  (15868)  |

|22.108   |         v17-14400-long-training       |                   |t38:t30 Ind:v17-14400-long-training

|         |(16460)  -------------------------------------->  (15868)  |

|24.052   |         v21-preamble                  |                   |t38:t30 Ind:v21-preamble

|         |(16460)  <--------------------------------------  (15870)  |

|25.942   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  <--------------------------------------  (15870)  |

|26.212   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  <--------------------------------------  (15870)  |

|26.262   |         no-signal |                   |                   |t38:t30 Ind:no-signal

|         |(16460)  <--------------------------------------  (15870)  |

|27.200   |         v21-preamble                  |                   |t38:t30 Ind:v21-preamble

|         |(16460)  -------------------------------------->  (15868)  |

|28.798   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  -------------------------------------->  (15868)  |

|29.119   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  -------------------------------------->  (15868)  |

|29.158   |         no-signal |                   |                   |t38:t30 Ind:no-signal

|         |(16460)  -------------------------------------->  (15868)  |

|29.439   |         v17-14400-long-training       |                   |t38:t30 Ind:v17-14400-long-training

|         |(16460)  -------------------------------------->  (15868)  |

|31.383   |         v21-preamble                  |                   |t38:t30 Ind:v21-preamble

|         |(16460)  <--------------------------------------  (15870)  |

|33.268   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  <--------------------------------------  (15870)  |

|33.538   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  <--------------------------------------  (15870)  |

|33.588   |         no-signal |                   |                   |t38:t30 Ind:no-signal

|         |(16460)  <--------------------------------------  (15870)  |

|35.687   |         Ukn (0x00)                    |                   |t38:v21:HDLC:Ukn (0x00)

|         |(16460)  -------------------------------------->  (15868)  |

|35.718   |         no-signal |                   |                   |t38:t30 Ind:no-signal

|         |(16460)  -------------------------------------->  (15868)  |

|37.346   |         BYE       |                   |                   |SIP Request

|         |(5061)   ------------------>  (5060)   |                   |

|37.347   |         200 OK    |                   |                   |SIP Status

|         |(5061)   <------------------  (5060)   |                   |

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