[OpenSIPS-Users] multiple retransmissions on 4XX after ACK

Richard Robson rrobson at greenlightcrm.com
Fri Oct 7 20:46:07 CEST 2016


The ack is from the cp. opensips is sending the 4xx.
I'll try the same on another provider. Thanks for the info

On 7 Oct 2016 18:27, "Newlin, Ben" <Ben.Newlin at inin.com> wrote:

> The most likely cause is that there is something wrong in the format of
> the ACK which is causing the far end to not recognize it as being the ACK
> for that 4XX response. So the far end will continue to retransmit the 4XX
> response. On the OpenSIPS side, these are recognized as retransmissions so
> the previous response is resent without triggering the failure route.
>
>
>
> The reason it happens on 4XX but not on 200 OK is that ACKs within a
> dialog – for 200 OK responses to INVITE or BYE – are actually requests
> themselves and are sent end-to-end just like INVITEs and BYEs. These ACKs
> are constructed following the rules for any request within a dialog [1].
>
>
>
> ACKs to failure responses, however, are transmitted at the transaction
> layer which means in this case they are being generated by OpenSIPS
> directly. Transactional ACKs are not requests and the rules for
> constructing them are different [2]. The most important parts are that the
> Via and Request-URI headers must match those in the initial request exactly.
>
>
>
> I have encountered this problem several times when my manipulations of
> messages in the routing script cause the ACKs to be malformed. I would
> suggest capturing a SIP trace of the failing transaction and verify the ACK
> is constructed properly.
>
>
>
> [1] https://tools.ietf.org/html/rfc3261#section-12.2.1.1
>
> [2] https://tools.ietf.org/html/rfc3261#section-17.1.1.3
>
>
>
> Ben Newlin
>
>
>
> *From: *<users-bounces at lists.opensips.org> on behalf of Richard Robson <
> rrobson at greenlightcrm.com>
> *Organization: *Greenlight Innovation
> *Reply-To: *OpenSIPS users mailling list <users at lists.opensips.org>
> *Date: *Friday, October 7, 2016 at 12:46 PM
> *To: *OpenSIPS users mailling list <users at lists.opensips.org>
> *Subject: *[OpenSIPS-Users] multiple retransmissions on 4XX after ACK
>
>
>
> Hi Guys,
>
>
>
> Not sure if this a problem or normal behaviour or I'm doing something
> wrong.
>
>
>
>
>
> after a 4XX is sent and the ACK recieved I can see 3 retransmissions of
>
> the 4XX message all with corresponding ACKs. Whywould it re transmit
>
> after an ACK
>
>
>
> in the logs in the reply route I only see one. Is there something I
>
> should be doing or is this normal behaviour. It doesnt do it with BYEs
>
>
>
> We are testing with BT next wee and I'd like everything to be shipshape
>
>
>
> this is from the carrier to opensips
>
>
>
> │INVITE sip:441618501059 at gl-sip-03.greenlightcrm.com SIP/2.
>
>               PSTN CARRIER                       OPENSIPS
>
> │Record-Route: <sip:109.239.96.133;lr;ftag=0UUHS0000030000E
>
>            ──────────┬─────────
>
> ──────────┬─────────│01001u1J9XWPK0DDUY6X;did=e7f.7bf9fe87>
>
>                      │        INVITE (SDP) │         │Via: SIP/2.0/UDP
>
> 109.239.96.133:5060;branch=z9hG4bK547c.48
>
>    17:42:38.425641   │ ──────────────────────────> │         │a4d4.0
>
>          +0.004634   │      100 Giving a try │         │Via: SIP/2.0/UDP
>
> 194.145.191.131:5060;branch=z9hG4bK00E0F5
>
>    17:42:38.430275   │ <────────────────────────── │
>
> │0E45333EAEE2FDC3E18D
>
>          +0.105251   │         180 Ringing │         │From:
>
> <sip:01382250029 at 194.145.191.131>;tag=0UUHS000003000
>
>    17:42:38.535526   │ <────────────────────────── │
>
> │1D01001u1J9XWPK0DDUY6X
>
>          +0.128720   │         180 Ringing │         │To:
>
> <sip:441618501059 at 109.239.96.133>
>
>    17:42:38.664246   │ <<<──────────────────────── │         │Call-ID:
>
> 4515e0000ef5-57f7d085-4d7d4603-f256d18-48e7f14 at 12
>
>         +10.118555   │     408 Request Timeout │         │0.0.1
>
>    17:42:48.782801   │ <────────────────────────── │         │CSeq:
>
> 33717 INVITE
>
>          +0.000610   │             ACK │         │Contact:
>
> <sip:194.145.191.131:5060>
>
>    17:42:48.783411   │ ──────────────────────────> │
>
> │Allow-Events: refer
>
>          +0.436750   │     408 Request Timeout │         │Allow: INVITE,
>
> ACK, BYE, CANCEL, OPTIONS, PRACK, INFO, REF
>
>    17:42:49.220161   │ <<<──────────────────────── │         │, NOTIFY,
>
> SUBSCRIBE, UPDATE
>
>          +0.000636   │             ACK │         │Content-Type:
>
> application/sdp
>
>    17:42:49.220797   │ ────────────────────────>>> │
>
> │Max-Forwards: 69
>
>          +1.003961   │     408 Request Timeout │         │Supported:
>
> timer, replaces, histinfo, 100rel
>
>    17:42:50.224758   │ <<<──────────────────────── │
>
> │User-Agent: TELES-SBC
>
>          +0.000705   │             ACK │         │Content-Length:   463
>
>    17:42:50.225463   │ ────────────────────────>>> │         │
>
>          +2.005938   │     408 Request Timeout │         │v=0
>
>    17:42:52.231401   │ <<<──────────────────────── │         │o=-
>
> 1890151066 0 IN IP4 194.145.191.134
>
>          +0.000651   │             ACK │         │s=TELES-SBC
>
>    17:42:52.232052   │ ────────────────────────>>> │         │c=IN IP4
>
> 194.145.191.134
>
>                      │ │         │t=0 0
>
>>
>
>
> Regards,
>
>
>
>
>
> --
>
> Richard Robson
>
> Greenlight Support
>
> 01382 843843
>
> support at greenlightcrm.com
>
>
>
>
>
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