Return-Path: X-Original-To: sipcore@core3.amsl.com Delivered-To: sipcore@core3.amsl.com Received: from localhost (localhost [127.0.0.1]) by core3.amsl.com (Postfix) with ESMTP id A30843A694C for ; Fri, 29 Oct 2010 10:44:41 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -2.503 X-Spam-Level: X-Spam-Status: No, score=-2.503 tagged_above=-999 required=5 tests=[AWL=0.745, BAYES_00=-2.599, HELO_EQ_FR=0.35, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-1] Received: from mail.ietf.org ([64.170.98.32]) by localhost (core3.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id MGWPkzWg37CX for ; Fri, 29 Oct 2010 10:44:39 -0700 (PDT) Received: from p-mail1.rd.francetelecom.com (p-mail1.rd.francetelecom.com [195.101.245.15]) by core3.amsl.com (Postfix) with ESMTP id E3D493A67FC for ; Fri, 29 Oct 2010 10:44:38 -0700 (PDT) Received: from p-mail1.rd.francetelecom.com (localhost.localdomain [127.0.0.1]) by localhost (Postfix) with SMTP id 775F38B8005; Fri, 29 Oct 2010 19:47:18 +0200 (CEST) Received: from ftrdsmtp2.rd.francetelecom.fr (unknown [10.192.128.47]) by p-mail1.rd.francetelecom.com (Postfix) with ESMTP id 6C9A28B8002; Fri, 29 Oct 2010 19:47:18 +0200 (CEST) Received: from ftrdmel0.rd.francetelecom.fr ([10.192.128.56]) by ftrdsmtp2.rd.francetelecom.fr with Microsoft SMTPSVC(6.0.3790.4675); Fri, 29 Oct 2010 19:46:30 +0200 X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01CB7791.38F68DC2" Date: Fri, 29 Oct 2010 19:46:31 +0200 Message-ID: <9ECCF01B52E7AB408A7EB85352642141020FD443@ftrdmel0.rd.francetelecom.fr> In-Reply-To: <4C7FDBEE.6080305@nostrum.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [sipcore] Bypassing out-of-service intermediate Proxy Thread-Index: ActKwqukakXd2CSyR9G+Afh4w9O9dQsxhaSA References: <9ECCF01B52E7AB408A7EB8535264214101CD7EE2@ftrdmel0.rd.francetelecom.fr> <4C7FDBEE.6080305@nostrum.com> From: To: X-OriginalArrivalTime: 29 Oct 2010 17:46:30.0864 (UTC) FILETIME=[384BB500:01CB7791] Cc: sipcore@ietf.org Subject: Re: [sipcore] Bypassing out-of-service intermediate Proxy X-BeenThere: sipcore@ietf.org X-Mailman-Version: 2.1.9 Precedence: list List-Id: SIP Core Working Group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 29 Oct 2010 17:44:42 -0000 This is a multi-part message in MIME format. ------_=_NextPart_001_01CB7791.38F68DC2 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks for this answer. =20 I understand that the intention of this text in RFC 3261 is to fail over = to an alternate server that serves the same function. Though, it's not = explicitly stated. =20 However, I did not find any text in RFC 3261 that would make forbidden = failing over to a proxy further down the path. Moreover, I did not see = any problem to such behaviour. =20 Youssef=20 ________________________________ De : Adam Roach [mailto:adam@nostrum.com]=20 Envoy=E9 : jeudi 2 septembre 2010 19:17 =C0 : CHADLI Youssef RD-CORE-ISS Cc : sipcore@ietf.org Objet : Re: [sipcore] Bypassing out-of-service intermediate Proxy [as participant] This is talking about failing over to an alternate server that serves = the same function, not a proxy further down the path. This is a bit = clearer if you look at section 4.3 of RFC 3263. Trying to fail "around" the server by going to the next network element = in the route would *not* be compliant with RFC 3261 behavior. /a On 9/2/10 11:56 AM, youssef.chadli@orange-ftgroup.com wrote:=20 Hi all,=20 I have a question regarding routeing of SIP requests and usage of = ROUTE.=20 When a proxy or UA fails to send a SIP request to the next hop (because = this latter is not reachable) is it allowed to bypass this hop and send = the request to the hop whose URI is next in ROUTE header. According to section 21.5.4 of RFC 3261, this proxy behaviour seems = allowed. See text in bold below:=20 Any opinions on this?=20 21.5.4 503 Service Unavailable=20 The server is temporarily unable to process the request due to a = temporary overloading or maintenance of the server. The server MAY = indicate when the client should retry the request in a Retry-After = header field. If no Retry-After is given, the client MUST act as if it = had received a 500 (Server Internal Error) response. A client (proxy or UAC) receiving a 503 (Service Unavailable) SHOULD = attempt to forward the request to an alternate server. It SHOULD NOT = forward any other requests to that server for the duration specified in = the Retry-After header field, if present. Servers MAY refuse the connection or drop the request instead of = responding with 503 (Service Unavailable).=20 Youssef CHADLI=20 Orange Labs=20 =09 _______________________________________________ sipcore mailing list sipcore@ietf.org https://www.ietf.org/mailman/listinfo/sipcore ------_=_NextPart_001_01CB7791.38F68DC2 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Bypassing out-of-service intermediate Proxy

Thanks=20 for this answer.

 

I=20 understand that the intention of this text in RFC 3261 is to fail = over to=20 an alternate server that serves the same function. Though, it's not = explicitly=20 stated.

 

However,=20 I did not find any text in RFC 3261 that would make forbidden failing = over=20 to a proxy further down the path. =20 Moreover, I did not see any problem to such=20 behaviour.

 

Youssef 
De : Adam Roach = [mailto:adam@nostrum.com]=20
Envoy=E9 : jeudi 2 septembre 2010 = 19:17
=C0 : CHADLI=20 Youssef RD-CORE-ISS
Cc : = sipcore@ietf.org
Objet :=20 Re: [sipcore] Bypassing out-of-service intermediate = Proxy

[as participant]

This is talking about failing over to = an=20 alternate server that serves the same function, not a proxy further down = the=20 path. This is a bit clearer if you look at section 4.3 of RFC=20 3263.

Trying to fail "around" the server by going to the next = network=20 element in the route would *not* be compliant with RFC 3261=20 behavior.

/a

On 9/2/10 11:56 AM, youssef.chadli@orange-f= tgroup.com=20 wrote:=20

Hi = all,

I have a question = regarding=20 routeing of SIP requests and usage of ROUTE.

When a proxy or UA = fails to send a=20 SIP request to the next hop (because this latter is not reachable) is = it=20 allowed to bypass this hop and send the request to the hop whose URI = is next=20 in ROUTE header.

According to section = 21.5.4 of RFC=20 3261, this proxy behaviour seems allowed. See text in bold=20 below:

Any opinions on=20 this?

21.5.4 503 = Service=20 Unavailable


The = server is=20 temporarily unable to process the request due to a temporary = overloading or=20 maintenance of the server.  The server MAY indicate when the = client=20 should retry the request in a Retry-After header field.  If no=20 Retry-After is given, the client MUST act as if it had received a 500 = (Server=20 Internal Error) response.

A client = (proxy or UAC)=20 receiving a 503 (Service Unavailable) SHOULD attempt to forward the request to an alternate=20 server.  It SHOULD = NOT forward=20 any other requests to that server for the duration specified in the=20 Retry-After header field, if present.

Servers = MAY refuse the=20 connection or drop the request instead of responding with 503 (Service = Unavailable).


Youssef = CHADLI=20
Orange Labs=20 




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