[Serusers] SER and re-INVITE (ACK for 488 msg)

Wed Oct 13 19:04:11 CEST 2004

Thanks for your explanation Bogdan,

but don't you think that the local ACK should be
generated according the RE-INVITE that was sent by SER
instead of the one received by SER?

In this way the local ACK would be the same as if SER
has processed the ACK generated by the endpoint!

Regards,

Chuck.

--- Bogdan-Andrei IANCU <iancu at fokus.fraunhofer.de>
wrote:

> As described in RFC 3261, section 12.2 Requests
> within a Dialog :
> 
> "Requests within a dialog MAY contain Record-Route
> and Contact header 
> fields. However, these requests do not cause the
> dialog's route set to 
> be modified, although they may modify the remote
> target URI."
> 
> As the GW uses for the re-INVITE the route set
> learned via original 
> INVITE (there are 2 Route hdr in your re-INVITE),
> SER follows the same 
> principal and when generating the ACK, instead of
> using the RR from 
> re_INVITE reply, it uses also the Route set from
> RE-INVITE.
> 
> Anyhow, as you can see, the 488 reply doen't mirror
> at all the RR set, 
> since the .18 device knows that is a reply for a
> re-INVITE and the ROUTE 
> set is already established.
> 
> bogdan
> 
> 
> Chuck Ramirez wrote:
> 
> >Hello guys,
> >
> >I'm trying to understand what is happening with SER
> >and re-INVITEs (for T.38 fax). 
> >
> >I have the follwing scenario:
> >
> >
> >ATA -> Session Border(NAT) -> SER -> Cisco Gateway
> >
> >
> >The ATA connects to the Cisco gateway for a voice
> call
> >and when the gateway receives a fax tone is starts
> a
> >re-INVITE to try to negotiate T38 parameters. Then
> ATA
> >responds with 488 Not Supported Here and SER sends
> a
> >ACK back to the ATA before sending 488 to the
> gateway.
> >
> >In this ACK it seems that SER is adding an extra
> route
> >header as the INVITE that was sent to the ATA had
> only
> >one route header. Why SER is adding two route
> headers?
> >
> >
> >I'm attaching ngrep logs to this mail (with some
> >further comments), where:
> >
> >The IP 10.0.0.19 is the Proxy
> >The IP 10.0.0.67 is the gateway
> >The IP 10.0.0.18 is the Session Border (NAT)
> >
> >Thanks in advance,
> >
> >Chuck.
> >
> >
> >		
> >_______________________________
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> >
>
>------------------------------------------------------------------------
> >
> >#
> >U 10.0.0.67:50549 -> 10.0.0.19:5060
> >  INVITE sip:1234 at 10.0.0.19:5060;ftag=2482904200;lr
> SIP/2.0..Via: SIP/2.0/UDP  10.0.0.67:5060..Fro
> >  m:
>
<sip:1234 at proxy.com;user=phone>;tag=48235ADC-1DB8..To:
> <sip:55519 at proxy.com;user=phone>;
> >  tag=2482904200..Date: Thu, 07 Oct 2004 15:42:12
> GMT..Call-ID: 137792672 at 10.0.0.35..Route:
> >   <sip:1234 at 10.0.0.18:5071>,
> <sip:55519 at 10.0.0.18:5071;user=phone>..Supported:
> timer,100rel..Min-
> >  SE:  1800..Cisco-Guid:
>
1053952464-397283801-2441193380-2221309272..User-Agent:
> Cisco-SIPGateway/IOS-12.x..
> >  Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK,
> COMET, REFER, SUBSCRIBE, NOTIFY, INFO..CSeq: 101
> INVITE..
> >  Max-Forwards: 6..Remote-Party-ID:
>
<sip:55519 at 10.0.0.67>;party=calling;screen=no;privacy=off..Timestam
> >  p: 1097163732..Contact:
> <sip:747%23555133280636 at 10.0.0.67:5060>..Expires:
> 180..Allow-Events: telephon
> >  e-event..Content-Type:
> application/sdp..Content-Length:
> 402....v=0..o=CiscoSystemsSIP-GW-UserAgent 8783 11
> >  68 IN IP4 10.0.0.67..s=SIP Call..c=IN IP4
> 10.0.0.67..t=0 0..m=image 18742 udptl t38..c=IN IP4
> 20
> > 
>
0.175.202.67..a=T38FaxVersion:0..a=T38MaxBitRate:14400..a=T38FaxFillBitRemoval:0..a=T38FaxTranscodingMMR:0
> > 
>
..a=T38FaxTranscodingJBIG:0..a=T38FaxRateManagement:transferredTCF..a=T38FaxMaxBuffer:200..a=T38FaxMaxData
> >  gram:72..a=T38FaxUdpEC:t38UDPRedundancy..
> >#
> >U 10.0.0.19:5060 -> 10.0.0.67:5060
> >  SIP/2.0 100 Trying..Via: SIP/2.0/UDP 
> 10.0.0.67:5060..From: <sip:1234 at proxy.com;user=
> >  phone>;tag=48235ADC-1DB8..To:
>
<sip:55519 at proxy.com;user=phone>;tag=2482904200..Call-ID:
> 13
> >  7792672 at 10.0.0.35..CSeq: 101 INVITE..Server:  Sip
> Router..Content-Length: 0....
> >#
> >
> >====The INVITE sent to the ATA has only one route
> header======
> >
> >
> >U 10.0.0.19:5060 -> 10.0.0.18:5071
> >  INVITE sip:1234 at 10.0.0.18:5071
> SIP/2.0..Record-Route:
> <sip:1234 at 10.0.0.19;ftag=48235ADC-1DB8;lr>
> >  ..Via: SIP/2.0/UDP
> 10.0.0.19;branch=z9hG4bK2c09.8631afe3.0..Via:
> SIP/2.0/UDP  10.0.0.67:5060..Fr
> >  om:
>
<sip:1234 at proxy.com;user=phone>;tag=48235ADC-1DB8..To:
> <sip:55519 at proxy.com;user=phone>;
> >  tag=2482904200..Date: Thu, 07 Oct 2004 15:42:12
> GMT..Call-ID: 137792672 at 10.0.0.35..Route
> >  :
> <sip:55519 at 10.0.0.18:5071;user=phone>..Supported:
> timer,100rel..Min-SE:  1800..Cisco-Guid: 10539524
> >  64-397283801-2441193380-2221309272..User-Agent:
> Cisco-SIPGateway/IOS-12.x..Allow: INVITE, OPTIONS,
> BYE, CA
> >  NCEL, ACK, PRACK, COMET, REFER, SUBSCRIBE,
> NOTIFY, INFO..CSeq: 101 INVITE..Max-Forwards:
> 5..Remote-Party-I
> >  D:
>
<sip:55519 at 10.0.0.67>;party=calling;screen=no;privacy=off..Timestamp:
> 1097163732..Contact: <sip:74
> >  7%23555133280636 at 10.0.0.67:5060>..Expires:
> 180..Allow-Events: telephone-event..Content-Type:
> applicat
> >  ion/sdp..Content-Length:
> 402....v=0..o=CiscoSystemsSIP-GW-UserAgent 8783 1168
> IN IP4 10.0.0.67..s=SIP
> >   Call..c=IN IP4 10.0.0.67..t=0 0..m=image 18742
> udptl t38..c=IN IP4 10.0.0.67..a=T38FaxVersion:0
> > 
>
..a=T38MaxBitRate:14400..a=T38FaxFillBitRemoval:0..a=T38FaxTranscodingMMR:0..a=T38FaxTranscodingJBIG:0..a=
> > 
>
T38FaxRateManagement:transferredTCF..a=T38FaxMaxBuffer:200..a=T38FaxMaxDatagram:72..a=T38FaxUdpEC:t38UDPRe
> >  dundancy..
> >#
> >U 10.0.0.18:5071 -> 10.0.0.19:5060
> >  SIP/2.0 488 Not Acceptable Here..Via: SIP/2.0/UDP
> 10.0.0.19;branch=z9hG4bK2c09.8631afe3.0..Via: SIP/2
> >  .0/UDP 10.0.0.67:5060..From:
>
<sip:1234 at proxy.com;user=phone>;tag=48235ADC-1DB8..To:
> <
> > 
>
sip:55519 at proxy.com;user=phone>;tag=2482904200..Call-ID:
> 137792672 at 10.0.0.35..CSeq: 101 IN
> >  VITE..timestamp: 1097163732..server: Cisco ATA
> 186  v3.1.0 atasip (040211A)..warning: Media type
> not avail
> >  able..Allow: ACK, BYE, CANCEL, INVITE, NOTIFY,
> OPTIONS, REFER, REGISTER..Content-Length: 0....
> >#
> >
> >===========The ACK sent to ATA has two route
> headers, and the top route header is the same as the
> R-Uri.
> >===========Is this correct?
> >
> >
> >
> >U 10.0.0.19:5060 -> 10.0.0.18:5071
> >  ACK sip:1234 at 10.0.0.18:5071 SIP/2.0..Via:
> SIP/2.0/UDP
> 10.0.0.19;branch=z9hG4bK2c09.8631afe3.0..F
> >  rom:
>
<sip:1234 at proxy.com;user=phone>;tag=48235ADC-1DB8..Call-ID:
> 137792672 at 10.0.0.35..To:
> > 
>
<sip:55519 at proxy.com;user=phone>;tag=2482904200..CSeq:
> 101 ACK..Route: <sip:1234 at 10.0.0.18:5071>, 
> > 
> <sip:55519 at 10.0.0.18:5071;user=phone>..User-Agent: 
=== message truncated ===

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