One document matched: draft-das-mipshop-andsf-dhcp-options-04.txt
Differences from draft-das-mipshop-andsf-dhcp-options-03.txt
Internet Engineering Task Force Subir Das
Internet-Draft Telcordia Technologies
Intended status: Proposed Standard Gabor Bajko
Expires: February 02, 2011 Nokia
July 02, 2010
Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Options for
Access Network Discovery and Selection Function(ANDSF) Discovery
draft-das-mipshop-andsf-dhcp-options-04
Status of this Memo
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ANDSF DHCP Options July 2010
Abstract
This document defines new Dynamic Host Configuration Protocol
(DHCPv4 and DHCPv6) options to enable a mobile node to discover
Access Network Discovery and Selection Function (ANDSF) entities
in an IP network. ANDSF is being developed in 3GPP and provides
inter-system mobility policies and access network specific
information to the mobile nodes(MNs).
Table of Contents
1. Introduction .................................................2
2. ANDSF IPv4 address option for DHCPv4..........................3
3. ANDSF IPv6 address option for DHCPv6..........................4
4. Option Usage..................................................5
4.1 Usage of ANDSF Options for DHCPv4.......................5
4.2 Usage of ANDSF Options for DHCPv6.......................6
5. Security Considerations ......................................6
6. IANA Considerations ..........................................6
7. Acknowledgements .............................................7
8. References ...................................................7
8.1 Normative References ....................................7
8.2 Informative References ..................................7
Author's Addresses ..............................................8
(1) Conventions used in this document
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.
(2) Terminology and abbreviations used in this document
ANDSF (Access Network Discovery and Selection Function): An entity
that provides network discovery and selection assistance data to the
user entity (UE) as per operator policy [3GPP TS 23.402].
Access Network: A network that is accessed by the user entity(UE)
3GPP Network: A radio access network specified by Third Generation
Partnership Project
Non-3GPP Network: A radio access network specified outside 3GPP by
Other Projects or Standards Organizations.
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1. Introduction
Access Network Discovery and Selection Function (ANDSF) is being
defined in 3GPP [3GPPTS23.402] to provide necessary network
discovery and selection assistance data to the mobile nodes for
multi-access network scenarios where 3GPP access-network level
solutions are not sufficient for the mobile nodes to perform
network discovery and selection of non-3GPP networks.
The information provided by ANDSF contains inter-system mobility
policies and access network specific data to assist the mobile
node with performing the inter-system handover. This set of
information can either be provisioned in the mobile node by the
home operator, or provided to the mobile node (MN) dynamically by
the ANDSF over the S14 reference point as defined in [3GPPTS23.402].
In 3GPP, the ANDSF is located either in the subscriber's home
operator or visited network and needs to be known to the MN or
discovered by the MN. According to [3GPPTS23.402] the ANDSF is
discovered through interaction with the Domain Name Service function
or the DHCP Server function.
This document defines new DHCPv4 and DHCPv6 options called the ANDSF
IP Address Option and ANDSF Domain List Option, which allow the MN
to locate an ANDSF Server.
2. ANDSF IPv4 Address Option for DHCPv4
This section describes the ANDSF IPv4 Address Option for DHCPv4.
The Option begins with an option code followed by a length and one
or more IP addresses. The option layout is depicted below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Code | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Code
OPTION-IPv4_Address-ANDSF(To Be Assigned) - 1 byte
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Length
An 8-bit field indicating the length of the option
excluding the 'Option Code' and the 'Length' fields
IP Address
IPv4 address(es) of ANDSF Server(s)
If the length is followed by a list of IPv4 addresses indicating
appropriate ANDSF servers available to the MN, servers MUST be
listed in order of preference and the client should process them
in decreasing order of preference. The Option has the following
format:
Code Len IPv4 Address 1 IPv4 Address 2
+-----+----+----+----+----+----+----+----+----
| XX | n |a1 | a2 | a3 | a4 | a1 | ...
+-----+----+----+----+----+----+----+----+----
3. ANDSF IPv6 Address option for DHCPv6
This section describes the ANDSF IPv6 Address Option for DHCPv6.
The Option begins with an option code followed by a length
and one or more IP addresses. The value of the length octet does
not include itself or the option code. The option layout is
depicted below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Code | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Code
OPTION-IPv6_Address-ANDSF (To Be Assigned) - 2 bytes
Length
A 16-bit field indicating the length of the option
excluding the 'Option Code' and the 'Length' fields.
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IP Address
IPv6 address(es) of ANDSF Server(s)
The Option follows the same format (except the Option Code and
Length value) as described in Section 2. The value of the Option
Code and Length are 2-octets and the Length does not include
itself or the Option Code field.
If the length is followed by a list of IPv6 addresses indicating
appropriate ANDSF servers available to the MN, servers MUST be
listed in order of preference and the client should process them in
decreasing order of preference.
4. Option Usage
4.1 Usage of ANDSF Options for DHCPv4
The requesting and sending of the proposed DHCPv4 options follow the
rules for DHCP options in [RFC2131].
4.1.1 Mobile Node behavior
The mobile node performs ANDSF discovery procedure either during
initial association with a network or when the policy and access
network information is required from ANDSF. It may also try to
perform the ANDSF discovery when the network information is outdated
or mobile does not have any ANDSF information.
In order to request an address of a ANDSF Server, the mobile node
(DHCP client) MUST include an ANDSF IPv4 Address Option in the
Parameter Request List(PRL)in the respective DHCP messages as
defined in [RFC2131] and [RFC2132].
If the mobile node receives no address, it may either try another
server or may continue to retransmit the PRL message. However, it
MUST limit the rate at which it retransmits the message and limit
the duration of the time during which it retransmits the message.
4.1.2 DHCP Server behavior
When the DHCP server receives an ANDSF IPv4 Address Option in the
PRL, the DHCP server MUST include the option in its response
messages (as defined in [RFC2131]and [RFC2132])that may contain a
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list of one or more IP addresses of the ANDSF server hosting the
service.
4.2 Usage of ANDSF Options for DHCPv6
The requesting and sending of the proposed DHCPv6 options follow the
rules for DHCP options in [RFC3315].
4.2.1 Mobile node behavior
The mobile node performs ANDSF discovery according to the procedures
described in Section 4.1.1.
In order to discover the address of an ANDSF Server, the mobile
node(DHCP client) MUST include an ANDSF IPv6 Address Option in the
Option Request Option (ORO) in the respective DHCP messages as
defined in [RFC3315].
If the mobile node receives no address, it may either try another
server or may continue to retransmit the ORO message. However, it
MUST limit the rate at which it retransmits the message and limit
the duration of the time during which it retransmits the message.
4.2.2 DHCP Server behavior
When the DHCP Server receives an ANDSF IPv6 Address Option in the
ORO, the DHCP server MUST include the option in its response (as
defined in [RFC3315])that may contain a list of one or more IP
addresses of the ANDSF server hosting the service.
5. Security Considerations
The security considerations in [RFC2131] apply. If an adversary
manages to modify the response from a DHCP server or insert its own
response, an MN could be led to contact a rogue ANDSF Server.
It is recommended to use DHCP authentication option described in
[RFC3118] where available. This will also protect the denial of
service attacks to DHCP servers. [RFC3118] provides mechanisms for
both entity authentication and message authentication.
In deployments where DHCP authentication is not available, 3GPP
specific lower layer security services may be sufficient to protect
DHCP messages. 3GPP ANDSF framework also provides additional
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mechanisms that protect message exchanges between ANDSF client and
server at the higher layer.
6. IANA Considerations
This document defines two new DHCP options as described in Sections
2 and 3.
ANDSF IPv4 Address Option for DHCPv4(OPTION-IPv4_Address-ANDSF) TBA
ANDSF IPv6 Address Option for DHCPv6 (OPTION-IPv6_Address-ANDSF) TBA
7. Acknowledgements
Authors would like to acknowledge the following individuals for
their valuable comments.
Patrick Stuper, Vijay Devarapalli, Jouni Korhonen, and Jari Arkko,
8. References
8.1 Normative References
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, March 1997.
[RFC2132] S. Alexander, Droms, R. ?DHCP Options and BOOTP Vendor
Extensions?, RFC 2132, March 1997
[RFC3315] Droms, R., et al, ?Dynamic Host Configuration Protocol
for IPv6 (DHCPv6), RFC 3315, July 2003
[RFC3118] Authentication for DHCP Messages, Droms et al, June 2001
8.2 Informative References
[3GPP TS23.402] www.3gpp.org/ftp/Specs/html-info/23402.htm
3GPP TS 23.402 V8.8.0 (2009-12): Architecture
enhancements for non-3GPP accesses (Release 8)
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[3GPP Ts 24.302] www.3gpp.org/ftp/Specs/html-info/24302.htm
3GPP TS 24.302 V8.4.1 (2009-12): Access to the 3GPP
Evolved Packet Core (EPC) via non-3GPP access
networks; Stage 3;(Release 8)
Authors' Addresses
Subir Das
Telcordia Technologies Inc.
e-mail: subir(at)research(dot)Telcordia(dot)com
Gabor Bajko
Nokia
e-mail: gabor(dot)bajko(at)nokia(dot)com
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