6man Working Group M. Boucadair
Internet-Draft D. Binet
Intended status: Standards Track France Telecom
Expires: April 7, 2013 October 4, 2012
IPv6 RA Option for SIP Proxy Server
draft-boucadair-6man-sip-proxy-01
Abstract
This document specifies a new optional extension to IPv6 Router
Advertisement messages to advertise SIP Proxy Server (e.g., P-CSCF)
addresses to IPv6 hosts.
The provisioning of the SIP Proxy Server address is crucial for the
delivery of SIP-based services. Means to ensure reliable delivery of
this information to connecting SIP User Agents is a must.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 7, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. SIP Proxy Server Option . . . . . . . . . . . . . . . . . . . . 4
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Normative References . . . . . . . . . . . . . . . . . . . 5
5.2. Informative References . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
1.1. Needs
Access to SIP-based service offerings (e.g., telephony) relies on the
provisioning of the IP address or FQDN of the outbound SIP Proxy
Server [RFC3261]. Two means have been defined in the past to
provision such information:
1. DHCPv6 SIP options [RFC3319].
2. Dedicated 3GPP PCO to convey the address of the P-CSCF [CORE].
Nevertheless, these means are not sufficient because of the following
reasons:
1. PCO-IE is not mandatory in 3G networks (e.g., PCO information may
not be supported by terminals);
2. DHCPv6 is not required in all 3GPP releases. Moreover, the
support of DHCPv6 client is not mandatory in the IETF IPv6 node
requirements.
3. PCO-IE is not available in non-3GPP networks. This is very
critical when the UE (User Equipment) performs a network
attachment in a non-3GPP network because the user won't have
access to SIP-based services if no alternative means are
supported.
As a conclusion, auto-configuration [RFC4861] is required so that a
SIP UA (User Agent) can learn one or multiple SIP Proxy Servers.
1.2. Scope
This document defines a new ND option called SIP Proxy Server option
that contains the domain name of SIP Proxy Server(s). This option
follows the procedures defined in [RFC4861]. The IPv6 host embedding
a SIP UA can learn a list of SIP Proxy Servers using this option.
This option can be sent along with other options, such as DNS
information [RFC6106], in the same RA message.
The router sending the SIP Proxy Server in RA must be configured with
the Proxy Server information.
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2. SIP Proxy Server Option
The SIP Proxy Server Option contains a domain name representing the
SIP outbound Proxy Server (e.g., SBE, P-CSCF). Figure 1 shows the
format of the SIP Proxy Server Option.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
: SIP Server Domain Name :
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
Where
o Type: To be assigned (RA SIP Proxy Server Option).
o Length is a 8-bit unsigned integer. The length of the option is
in unit of 8 octets.
o Reserved is for future use.
o Lifetime is a 16-bit unsigned integer. Same as in [RFC6106].
o SIP Server Domain Name: The domain names of the SIP outbound proxy
servers for the client to use. The domain names are encoded as
specified Section 3.1 of [RFC1035]. The domain names MUST NOT be
encoded in a compressed form, as described in Section 4.1.4 of
[RFC1035].
Upon receipt of an RA SIP Proxy Server option, the IPv6 host MUST
verify that the option length does not exceed 255 octets [RFC1035].
The IPv6 host MUST verify the FQDN is properly encoded as detailed in
Section 3.1 of [RFC1035].
Once the FQDN conveyed in a SIP Proxy Server RA option is validated,
the included name is passed to the name resolution library (e.g.,
Section 6.1.1 of [RFC1123] or [RFC6055]) to retrieve the
corresponding IP address.
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3. IANA Considerations
This document requests IANA to assign a new option code for:
SIP Proxy Server
4. Security Considerations
The security considerations discussed in [RFC4861] and [RFC3261] must
be taken into account.
This option can be used to inject a fake proxy server which will
discover the security credentials used by legitimate user to connect
to their SIP services. This threat is similar to what is discussed
in [RFC6106].
5. References
5.1. Normative References
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
5.2. Informative References
[CORE] 3GPP 24.008, "3GPP 24.008 -- Mobile radio interface Layer
3 specification; Core network protocols; Stage 3",
December 2008.
[RFC1123] Braden, R., "Requirements for Internet Hosts - Application
and Support", STD 3, RFC 1123, October 1989.
[RFC3319] Schulzrinne, H. and B. Volz, "Dynamic Host Configuration
Protocol (DHCPv6) Options for Session Initiation Protocol
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(SIP) Servers", RFC 3319, July 2003.
[RFC6055] Thaler, D., Klensin, J., and S. Cheshire, "IAB Thoughts on
Encodings for Internationalized Domain Names", RFC 6055,
February 2011.
[RFC6106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
"IPv6 Router Advertisement Options for DNS Configuration",
RFC 6106, November 2010.
Authors' Addresses
Mohamed Boucadair
France Telecom
Rennes, 35000
France
Email: mohamed.boucadair@orange.com
David Binet
France Telecom
Rennes
France
Email: david.binet@orange.com
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