From volkerh@bell-labs.com Thu Aug 20 06:52:38 2009 Return-Path: X-Original-To: sip-overload@core3.amsl.com Delivered-To: sip-overload@core3.amsl.com Received: from localhost (localhost [127.0.0.1]) by core3.amsl.com (Postfix) with ESMTP id 633FE3A6B78; Thu, 20 Aug 2009 06:52:38 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -2.599 X-Spam-Level: X-Spam-Status: No, score=-2.599 tagged_above=-999 required=5 tests=[BAYES_00=-2.599] 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 1KwzazV5ThTn; Thu, 20 Aug 2009 06:52:37 -0700 (PDT) Received: from ihemail4.lucent.com (ihemail4.lucent.com [135.245.0.39]) by core3.amsl.com (Postfix) with ESMTP id 6D6B43A695E; Thu, 20 Aug 2009 06:52:36 -0700 (PDT) Received: from ihrh1.emsr.lucent.com (h135-1-218-53.lucent.com [135.1.218.53]) by ihemail4.lucent.com (8.13.8/IER-o) with ESMTP id n7KDqdZf009272; Thu, 20 Aug 2009 08:52:39 -0500 (CDT) Received: from USNAVSXCHHUB02.ndc.alcatel-lucent.com (usnavsxchhub02.ndc.alcatel-lucent.com [135.3.39.111]) by ihrh1.emsr.lucent.com (8.13.8/emsr) with ESMTP id n7KDqc6Y022893; Thu, 20 Aug 2009 08:52:39 -0500 (CDT) Received: from [127.0.0.1] (135.3.63.243) by USNAVSXCHHUB02.ndc.alcatel-lucent.com (135.3.39.111) with Microsoft SMTP Server (TLS) id 8.1.375.2; Thu, 20 Aug 2009 08:52:38 -0500 Message-ID: <4A8D551B.7060308@alcatel-lucent.com> Date: Thu, 20 Aug 2009 09:52:27 -0400 From: Volker Hilt User-Agent: Thunderbird 2.0.0.22 (Windows/20090605) MIME-Version: 1.0 To: DISPATCH , SIP-OVERLOAD Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.57 on 135.245.2.39 Subject: [sip-overload] Revised Charter Proposal for SIP Overload X-BeenThere: sip-overload@ietf.org X-Mailman-Version: 2.1.9 Precedence: list List-Id: SIP Overload List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Aug 2009 13:52:38 -0000 All, below is an revised SIP Overload Control charter proposal. I have received a few comments that are reflected in the new proposal. All comments, thoughts, feedback is very welcome! Thanks, Volker SIP Overload Control WG Charter ------------------------------- As with any network element, a Session Initiation Protocol (SIP) server can suffer from overload when the number of SIP messages it receives exceeds the number of messages it can process. Overload is said to occur when a SIP server does not have sufficient resources to process all incoming SIP messages. These resources can include CPU, memory, network bandwidth, input/output, or disk resources. Overload can pose a serious problem for a network of SIP servers. During periods of overload, the throughput of a network of SIP servers can be significantly degraded. In fact, overload may lead to a situation in which the throughput drops down to zero or a small fraction of the original processing capacity. This is often called congestion collapse. The objective of a SIP overload control mechanism is to enable SIP servers to operate close to their capacity limit during times of overload. The SIP protocol provides a limited mechanism for overload control through its 503 (Service Unavailable) response code and the Retry-After header. However, this mechanism cannot fully prevent overload of a SIP server and it cannot prevent congestion collapse. In fact, its on/off behavior may cause traffic to oscillate and shift between SIP servers and thereby worsen an overload condition. A detailed discussion of the SIP overload problem, the problems with the 503 (Service Unavailable) response code and the Retry-After header and the requirements for a SIP overload control mechanism can be found in RFC5390. The objective of the proposed working group is to develop mechanisms for SIP overload control. Two complementary approaches exist for handling overload situations: - The first mechanism aims at preventing overload in SIP servers by adjusting the incoming load to a level that is acceptable for this server. This mechanism uses implicit and/or explicit feedback to determine when an overload condition occurs in a SIP server and a reduction in load is required. - The second mechanism aims at preventing overload in SIP servers by distributing load control filters to SIP servers that throttle calls based on their destination domain, telephone number prefix or for a specific user. Such filters can be used, for example, to throttle calls to a hotline during a ticket-giveaway event. Specifically, the proposed working group will develop the following deliverables: 1. A document describing key design considerations for a SIP overload control mechanism. 2. A specification for an SIP overload control mechanism based on implicit/explicit feedback. 3. A specification for a SIP load filtering mechanism. From volkerh@bell-labs.com Thu Aug 20 06:59:58 2009 Return-Path: X-Original-To: sip-overload@core3.amsl.com Delivered-To: sip-overload@core3.amsl.com Received: from localhost (localhost [127.0.0.1]) by core3.amsl.com (Postfix) with ESMTP id 1C57128C152 for ; Thu, 20 Aug 2009 06:59:58 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -2.599 X-Spam-Level: X-Spam-Status: No, score=-2.599 tagged_above=-999 required=5 tests=[BAYES_00=-2.599] 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 1Cv63tjdsVbs for ; Thu, 20 Aug 2009 06:59:57 -0700 (PDT) Received: from ihemail1.lucent.com (ihemail1.lucent.com [135.245.0.33]) by core3.amsl.com (Postfix) with ESMTP id 8DDF93A6808 for ; Thu, 20 Aug 2009 06:59:52 -0700 (PDT) Received: from ihrh1.emsr.lucent.com (h135-1-218-53.lucent.com [135.1.218.53]) by ihemail1.lucent.com (8.13.8/IER-o) with ESMTP id n7KDxvaf001650 for ; Thu, 20 Aug 2009 08:59:57 -0500 (CDT) Received: from USNAVSXCHHUB02.ndc.alcatel-lucent.com (usnavsxchhub02.ndc.alcatel-lucent.com [135.3.39.111]) by ihrh1.emsr.lucent.com (8.13.8/emsr) with ESMTP id n7KDxrQK009504 for ; Thu, 20 Aug 2009 08:59:57 -0500 (CDT) Received: from [127.0.0.1] (135.3.63.243) by USNAVSXCHHUB02.ndc.alcatel-lucent.com (135.3.39.111) with Microsoft SMTP Server (TLS) id 8.1.375.2; Thu, 20 Aug 2009 08:59:54 -0500 Message-ID: <4A8D56CE.60803@bell-labs.com> Date: Thu, 20 Aug 2009 09:59:42 -0400 From: Volker Hilt User-Agent: Thunderbird 2.0.0.22 (Windows/20090605) MIME-Version: 1.0 To: "sip-overload@ietf.org" Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.57 on 135.245.2.33 Subject: [sip-overload] Overload Control Related Drafts X-BeenThere: sip-overload@ietf.org X-Mailman-Version: 2.1.9 Precedence: list List-Id: SIP Overload List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Aug 2009 13:59:58 -0000 All, I'd like to bring the following drafts to your attention. These drafts address the different aspects of SIP overload control that are discussed in the charter proposal of the SIP overload control WG. http://tools.ietf.org/html/draft-ietf-sipping-overload-design-02 http://tools.ietf.org/html/draft-hilt-sipping-overload-06 http://tools.ietf.org/html/draft-shen-sipping-load-control-event-package-02 Please send comments on these drafts to this list! Thanks, Volker