Internet DRAFT - draft-gundavelli-ipsecme-3gpp-ims-options
draft-gundavelli-ipsecme-3gpp-ims-options
IPSECME WG A. Dodd-Noble
Internet-Draft S. Gundavelli
Intended status: Informational Cisco
Expires: October 25, 2015 J. Korhonen
F. Baboescu
Broadcom Corporation
B. Weis
Cisco
April 23, 2015
3GPP IMS Option for IKEv2
draft-gundavelli-ipsecme-3gpp-ims-options-05.txt
Abstract
This document defines two new configuration attributes for Internet
Key Exchange Protocol version 2 (IKEv2). These attributes can be
used for carrying the IPv4 address and IPv6 address of the Proxy-Call
Session Control Function (P-CSCF). When an IPsec gateway delivers
these attributes to an IPsec client, the IPsec client can obtain the
IPv4 and/or IPv6 address of the P-CSCF server located in the 3GPP
network.
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 October 25, 2015.
Copyright Notice
Copyright (c) 2015 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
Provisions Relating to IETF Documents
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(http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Terminology . . . . . . . . . . . . . . . . . . 4
2.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
3. P_CSCF_IP4_ADDRESS Configuration Attribute . . . . . . . . . . 5
4. P_CSCF_IP6_ADDRESS Configuration Attribute . . . . . . . . . . 5
5. Example Scenario . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
The Third Generation Partnership Project (3GPP) S2b reference point
[TS23402], specified by the 3GPP system architecture defines a
mechanism for allowing a mobile node (MN) attached in an untrusted
non-3GPP IP Access Network to securely connect to a 3GPP network and
access IP services. In this scenario, the mobile node establishes an
IPsec ESP tunnel [RFC4303] to the security gateway called evolved
packet data gateway (ePDG) and which in turn establishes a Proxy
Mobile IPv6 (PMIPv6) [RFC5213] or GPRS Tunneling Protocol (GTP)
[TS23402] tunnel to the packet data gateway (PGW) [TS23402] where the
mobile node's session is anchored.
The below figure shows the interworking option for non-3GPP access
over an untrusted-access network. The mobile access gateway (MAG)
and the local mobility anchor (LMA) functions are defined in
[RFC5213]. The ePDG and PGW functions are defined in [TS23402].
IPsec ESP tunnel is between the MN and the ePDG and PMIP or GTP
tunnel between the ePDG and the PGW.
+------------+
| ePDG |
| +--------+ |
+------+ _----_ | | IPsec | | _----_ +-----+
| MN | _( )_ | | Module | | _( )_ | LMA |
| |<====( Internet )=====| +--------+ |===( Operator )===|(PGW)|
+------+ (_ _) | : | (_Network_) +-----+
'----' | +--------+ | '----'
IPsec Tunnel | | PMIPv6 | | PMIPv6/GTP Tunnel
| | MAG | |
| +--------+ |
+------------+
|<------------ IKEv2/IPsec ------> | <------ PMIPv6/GTP ----->|
Figure 1: Exchange of IPv4 Traffic Offload Selectors
A mobile node in this scenario may potentially need to access the IP
Multimedia Subsystem (IMS) services in the 3GPP network [TS23228] and
[TS24229]. Currently, there are no attributes in IKEv2 [RFC7296]
that can be used for carrying these information elements. In the
absence of these attributes the mobile node needs to be statically
configured with this information and this is proving to be an
operational challenge. Any other approaches such as using DNS, or
DHCP for discovering these functions would result in obtaining
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configuration in the access network and not in the home network.
Given that the above referenced 3GPP interface is primarily for
allowing the mobile node to connect to the 3GPP network through an
untrusted-access network, the access network may not have any
relation with the home network provider and may be unable to deliver
the mobile node's home network configuration.
This specification therefore defines two new IKEv2 attributes
[RFC7296] that allows an IPsec gateway to provide the IPv4 and/or
IPv6 address of the P-CSCF server. These attributes can be exchanged
by IKEv2 peers as part of the configuration payload exchange. The
attributes follow the configuration attribute format defined in
Section 3.15.1 of [RFC7296]. Furthermore, providing the P-CSCF
server address(es) in IKEv2 as standard attribute(s) enables clients
to directly access IMS services behind a VPN gateway without going
through the 3GPP specific interfaces.
2. Conventions and Terminology
2.1. Conventions
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].
2.2. Terminology
All the IKEv2 related terms used in this document are to be
interpreted as defined in [RFC7296] and [RFC5739]. All the mobility
related terms are to interpreted as defined in [RFC5213] and
[RFC5844]. Additionally, this document uses the following terms:
Proxy-Call Session Control Function (P-CSCF)
The P-CSCF is the entry point to the 3GPP IMS (IP Multimedia
Subsystem) and serves as the SIP outbound proxy for the mobile
node. The mobile node performs SIP registration to 3GPP IMS and
initiates SIP sessions via a P-CSCF.
Evolved Packet Data Gateway (ePDG)
Its is a security gateway defined by the 3GPP system architecture.
The protocol interfaces it supports include IKEv2 [RFC7296].
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3. P_CSCF_IP4_ADDRESS Configuration Attribute
The P_CSCF_IP4_ADDRESS configuration attribute is formatted as
follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R| Attribute Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: IPv4 Address of P-CSCF
Reserved (1 bit)
Refer to IKEv2 specification
Attribute Type (15 bits)
<IANA-1>
Length (2 octets)
Length of the IPv4 address field that follows. Possible values
are (0) and (4). A value of (4) indicates the size of the 4-octet
IPv4 address that follows. A value of (0) indicates that its a
empty attribute with zero-length IPv4 address field, primarily
used as a request indicator.
IPv4 Address (4 octets)
An IPv4 address of the P-CSCF server.
The P_CSCF_IP4_ADDRESS configuration attribute provides an IPv4
address of a P-CSCF server within the network. If an instance of an
empty P_CSCF_IP4_ADDRESS attribute with zero-length IPv4 Address
field is included by mobile node, the responder MAY respond with
zero, one or more P_CSCF_IP4_ADDRESS attributes. If several
P_CSCF_IP4_ADDRESS attributes are provided in one IKEv2 message,
there is no implied order among the P_CSCF_IP4_ADDRESS attributes.
However, a system architecture using this specification may be able
to enforce some order at both the peers.
4. P_CSCF_IP6_ADDRESS Configuration Attribute
The P_CSCF_IP6_ADDRESS configuration attribute is formatted as
follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R| Attribute Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| IPv6 Address |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: IPv6 Address of P-CSCF
Reserved (1 bit)
Refer to IKEv2 specification
Attribute Type (15 bits)
<IANA-1>
Length (2 octets)
Length of the IPv6 address field that follows. Possible values
are (0) and (16). A value is (16) indicates the size of the 16-
octet IPv6 address that follows. A value of (0) indicates that
its a empty attribute with zero-length IPv6 address field,
primarily used as a request indicator.
IPv6 Address (16 octets)
An IPv6 address of the P-CSCF server.
The P_CSCF_IP6_ADDRESS configuration attribute provides an IPv6
address of a P-CSCF server within the network. If an instance of an
empty P_CSCF_IP6_ADDRESS attribute with zero-length IPv6 Address
field is included by mobile node, the responder MAY respond with
zero, one or more P_CSCF_IP6_ADDRESS attributes. If several
P_CSCF_IP6_ADDRESS attributes are provided in one IKEv2 message,
there is no implied order among the P_CSCF_IP6_ADDRESS attributes.
However, a system architecture using this specification may be able
to enforce some order at both the peers.
5. Example Scenario
The mobile node MAY request the IP address of an P-CSCF server as
shown below.
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Client Gateway
-------- ---------
HDR(IKE_SA_INIT), SAi1, KEi, Ni -->
<-- HDR(IKE_SA_INIT), SAr1, KEr, Nr, [CERTREQ]
HDR(IKE_AUTH),
SK { IDi, CERT, [CERTREQ], AUTH, [IDr],
CP(CFG_REQUEST) =
{ INTERNAL_IP4_ADDRESS(),
INTERNAL_IP4_DNS(),
P_CSCF_IP4_ADDRESS() }, SAi2,
TSi = (0, 0-65535, 0.0.0.0-255.255.255.255),
TSr = (0, 0-65535, 0.0.0.0-255.255.255.255) } -->
<-- HDR(IKE_AUTH),
SK { IDr, CERT, AUTH,
CP(CFG_REPLY) =
{ INTERNAL_IP4_ADDRESS(192.0.2.234),
P_CSCF_IP4_ADDRESS(192.0.2.1),
P_CSCF_IP4_ADDRESS(192.0.2.4),
INTERNAL_IP4_DNS(198.51.100.33) },
SAr2,
TSi = (0, 0-65535, 192.0.2.234-192.0.2.234),
TSr = (0, 0-65535, 0.0.0.0-255.255.255.255) }
Figure 4: P-CSCF Attribute Exchange
6. IANA Considerations
This document requires the following two IANA actions.
o Action-1: This specification defines a new IKEv2 attribute for
carrying the IPv4 address of P-CSCF server. This attribute is
defined in Section 3. The Type value for this Attribute needs to
be assigned from the IKEv2 Configuration Payload Attribute Types
namespace defined in [RFC7296].
o Action-2: This specification defines a new IKEv2 attribute for
carrying the IPv6 address of P-CSCF server. This attribute is
defined in Section 4. The Type value for this Attribute needs to
be assigned from the IKEv2 Configuration Payload Attribute Types
namespace defined in [RFC7296].
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7. Security Considerations
This document is an extension to IKEv2 [RFC7296] and therefore it
inherits all the security properties of IKEv2.
The two new IKEv2 attributes defined in this specification are for
carrying the IPv4 and IPv6 address of the P-CSCF server. These
attributes can be exchanged by IKE peers as part of the configuration
payload and the currently defined IKEv2 security framework provides
the needed integrity and privacy protection for these attributes.
Therefore this specification does not introduce any new security
vulnerabilities.
8. Acknowledgements
The Authors would like to specially thank Tero Kivinen for the
detailed reviews. Authors would also like to thank Vojislav Vucetic,
Heather Sze, Sebastian Speicher, Maulik Vaidya, Ivo Sedlacek,
Pierrick Siete and Hui Deng for all the discussions related to this
topic.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, December 2005.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, October 2014.
9.2. Informative References
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC5739] Eronen, P., Laganier, J., and C. Madson, "IPv6
Configuration in Internet Key Exchange Protocol Version 2
(IKEv2)", RFC 5739, February 2010.
[RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", RFC 5844, May 2010.
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[TS23228] 3GPP, "Service requirements for the Internet Protocol (IP)
multimedia core network subsystem (IMS); Stage 1", 2014.
[TS23402] 3GPP, "Architecture enhancements for non-3GPP accesses",
2014.
[TS24229] 3GPP, "IP multimedia call control protocol based on
Session Initiation Protocol (SIP) and Session Description
Protocol (SDP); Stage 3", 2014.
Authors' Addresses
Aeneas Noble
Cisco
30 International Pl
TEWKSBURY, MASSACHUSETTS 95134
USA
Email: noblea@cisco.com
Sri Gundavelli
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
Email: sgundave@cisco.com
Jouni Korhonen
Broadcom Corporation
Porkkalankatu 24
Helsinki FIN-00180
Finland
Email: jouni.nospam@gmail.com
Florin Baboescu
Broadcom Corporation
100 Mathilda Place
Sunnyvale, CA 94086
USA
Email: baboescu@broadcom.com>
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Brian Weis
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
Email: bew@cisco.com
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