draft-ietf-sipping-sbc-funcs-06.txt   draft-ietf-sipping-sbc-funcs-07.txt 
SIPPING Working Group J. Hautakorpi, Ed. SIPPING Working Group J. Hautakorpi, Ed.
Internet-Draft G. Camarillo Internet-Draft G. Camarillo
Intended status: Informational Ericsson Intended status: Informational Ericsson
Expires: December 18, 2008 R. Penfield Expires: April 26, 2009 R. Penfield
Acme Packet Acme Packet
A. Hawrylyshen A. Hawrylyshen
Ditech Networks Inc. Ditech Networks Inc.
M. Bhatia M. Bhatia
3CLogic 3CLogic
June 16, 2008 October 23, 2008
Requirements from SIP (Session Initiation Protocol) Session Border Requirements from SIP (Session Initiation Protocol) Session Border
Control Deployments Control Deployments
draft-ietf-sipping-sbc-funcs-06.txt draft-ietf-sipping-sbc-funcs-07.txt
Status of this Memo Status of this Memo
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This Internet-Draft will expire on December 18, 2008. This Internet-Draft will expire on April 26, 2009.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
Abstract Abstract
This document describes functions implemented in Session Initiation This document describes functions implemented in Session Initiation
Protocol (SIP) intermediaries known as Session Border Controllers Protocol (SIP) intermediaries known as Session Border Controllers
(SBCs). The goal of this document is to describe the commonly (SBCs). The goal of this document is to describe the commonly
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SBCs are also used to repair protocol messages generated by not- SBCs are also used to repair protocol messages generated by not-
fully-standard compliant or badly implemented clients. Operators may fully-standard compliant or badly implemented clients. Operators may
wish to support protocol repair, if they want to support as many wish to support protocol repair, if they want to support as many
clients as possible. It is noteworthy, that this function affects clients as possible. It is noteworthy, that this function affects
only the signaling component of an SBC, and that the protocol repair only the signaling component of an SBC, and that the protocol repair
function is not the same as protocol conversion (i.e., making function is not the same as protocol conversion (i.e., making
translation between two completely different protocols). translation between two completely different protocols).
3.6.2. Architectural Issues 3.6.2. Architectural Issues
In most cases, this function can be seen as being compatible with SIP In many cases, doing protocol repair for SIP header fields can be
architectural principles, and it does not violate the end-to-end seen as being compatible with SIP architectural principles, and it
model of SIP. The SBC repairing protocol messages behaves as a proxy does not violate the end-to-end model of SIP. The SBC repairing
server that is liberal in what it accepts and strict in what it protocol messages behaves as a proxy server that is liberal in what
sends. However, the protocol repair might have problems with such it accepts and strict in what it sends.
security mechanism that do cryptographical computations to the SIP
messages (e.g., hashing). However, protocol repair may break security mechanism that do
cryptographical computations on SIP header values. Attempting
protocol repair for SIP message bodies (SDP) is incompatible with
Authenticated Identity Management [3] and end-to-end security
mechanisms such as S/MIME.
A similar problem related to increasing complexity, as explained in A similar problem related to increasing complexity, as explained in
Section 3.3.2, also affects protocol repair function. Section 3.3.2, also affects protocol repair function.
3.6.3. Examples 3.6.3. Examples
The SBC can, for example, receive an INVITE message from a relatively The SBC can, for example, receive an INVITE message from a relatively
new SIP UA as illustrated in Figure 13. new SIP UA as illustrated in Figure 13.
INVITE sip:callee@sbchost.example.com INVITE sip:callee@sbchost.example.com
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