Re: [sipcore] Open issues in draft-ietf-sipcore-sip-websocket-09

Iñaki Baz Castillo <ibc@aliax.net> Sun, 16 June 2013 21:15 UTC

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From: Iñaki Baz Castillo <ibc@aliax.net>
Date: Sun, 16 Jun 2013 23:14:58 +0200
Message-ID: <CALiegf=U9fNPcL83TbWPQirNczZ-faHmG1R+AiPVuBLa=pfe6A@mail.gmail.com>
To: Parthasarathi R <partha@parthasarathi.co.in>
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Cc: "SIPCORE (Session Initiation Protocol Core) WG" <sipcore@ietf.org>
Subject: Re: [sipcore] Open issues in draft-ietf-sipcore-sip-websocket-09
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2013/6/16 Parthasarathi R <partha@parthasarathi.co.in>:
> Hi Inaki,
>
> Open Item 2 comment: The current statement states that
>
>      " All SIP elements MUST implement at least one of the following:
>
>       *  Both UDP and TCP transports.
>
>       *  SIP WebSocket transport."
>
> I could not understand how this update resolve the issue in the following scenario:
>
>  SIP UA1 (WS only)----Proxy-----SIP UA2 (UDP/TCP)
>
> Here, the dialog is established with contact details for SIP UA1 & SIP UA2 as follows:
>
> 1) contact: sip:sipua1@example.com;transport=ws
> 2) contact: sip:sipua2@example.com;transport=tcp
>
> In case SIP UA2 wishes to send RE-INVITE towards SIP UA1, how does it possible now as per the current update in Sec 5.2.4 of draft-ietf-sipcore-sip-websocket-09.


Hi Parthasarathi, this subject was heavily discussed during the past
year. It's clear that in 99% or 100% of cases, a SIP WebSocket Client
(i.e. a browser) will not be able to receive incoming WS connections
(it is not a SIP WebSocket Server) and thus, the proxy in your flow
has to perform record-routing, a *standard* mechanism defined in RFC
3261 for making your scenario feasible.

IMHO it is not so hard to assume that when SIP over WebSocket devices
are present, the proxy they connect to must perform record-routing.
The same is true for clients behind NAT.


Regards.


--
Iñaki Baz Castillo
<ibc@aliax.net>