Network Working Group K. Leung
Internet-Draft A. Patel
Expires: August 5, 2005 Cisco Systems
G. Tsirtsis
Flarion Technologies
E. Klovning
Birdstep Technology ASA
February 2005
Cisco Mobile IPv4 Host Configuration Extensions
draft-leung-cisco-mip4-host-config-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
An IP device requires basic host configuration to be able to
communicate. For example, the IP address on the interface and the
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DNS server for a hostname to IP address lookup. This information is
configured statically or obtained dynamically using Dynamic Host
Configuration Protocol (DHCP) or Point-to- Point Protocol/IP Control
Protocol (PPP/IPCP). However, both DHCP and PPP/IPCP provides host
configuration based on the access network. In Mobile IPv4, the
registration process boots up a Mobile Node at an access network,
also known as foreign network. The information to configure the host
needs to be based on the home network. This document describes the
Mobile IPv4 extensions used to provide the base host configuration in
the Registration Request and Reply messages.
The content is provided for informational purpose only.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Host Configuration Extensions Summary . . . . . . . . . . . . 5
4. Host Configuration Extensions . . . . . . . . . . . . . . . . 6
4.1 Host Configuration Request Extension . . . . . . . . . . . 6
4.2 Home Network Prefix Extension . . . . . . . . . . . . . . 7
4.3 DNS Server Extension . . . . . . . . . . . . . . . . . . . 7
4.4 DHCP Server Extension . . . . . . . . . . . . . . . . . . 8
4.5 DHCP Client ID Extension . . . . . . . . . . . . . . . . . 9
4.6 Default Gateway Extension . . . . . . . . . . . . . . . . 9
4.7 DNS Suffix Extension . . . . . . . . . . . . . . . . . . . 10
4.8 Configuration URL Extension . . . . . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . 15
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1. Introduction
An IPv4 device requires some basic configuration to communicate with
other nodes. Typically, it has an IP address for an interface and
DNS server's IP address to resolve the peer's hostname to an IP
address. DHCP [RFC2131] and PPP/IPCP [RFC1332] provides host
configuration information on the access network interface, but this
is inadequate. However, in Mobile IPv4 [RFC3344], a Mobile Node has
a virtual network interface on the home network, anchored by the Home
Agent. The IP address, home subnet prefix, default gateway, and home
network's DNS servers are essential in the boot up of a network
interface. In some cases, these are the only information needed by
the Mobile Node.
The Mobile IPv4 registration process provides the mechanism for a
Mobile Node to boot up on a foreign network. Upon the successful
registration, the Mobile Node can communicate with the Correspondent
Node. The need to provide an efficient method to obtain the host
configuration exists. If the Mobile Node is a DHCP client, it can
obtain configuration parameters from the DHCP server in the home
network after the initial registration.
This document introduces the Cisco vendor specific extensions
[RFC3115] to provide the means for a Mobile Node to download some
fundamental configuration associated with the home network via the
Home Agent. These extensions provide information for home subnet
prefix, DNS server, DHCP server, DHCP client identifier, default
gateway, DNS suffix, and configuration URL.
The home subnet prefix allows the Mobile Node to set up the subnet
mask on the virtual interface properly. The default gateway may be
the Home Agent's address, but at times, that address is the tunnel
endpoint on a virtual interface and not on the home subnet. In this
case, the extension provides the Home Agent's address or another
appropriate address to satisfy the network interface configuration on
the Mobile Node.
The DNS server's IP address and DNS suffix are based on the home
administrative domain.
The DHCP client ID and DHCP server's IP address provides information
for the Mobile Node to renew its home address with the DHCP server
when the Mobile Node returns home and the Home Agent is no longer
maintaining the home address of the Mobile Node
The configuration URL provides a convenient mechanism to download
additional configuration parameters of the Mobile Nodes from a
centralized repository.
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2. Terminology
The keywords "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.
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3. Host Configuration Extensions Summary
The following Cisco vendor specific extensions provide the host
configuration for a Mobile Node.
o Host Configuration Request
* Request for host configuration information from the Mobile Node
to the Home Agent.
o Home Network Prefix
* The subnet prefix on the home network.
o Default Gateway
* The default gateway's IP address on the home network.
o DNS Server
* The DNS server's IP address in the home network.
o DNS Suffix
* The DNS suffix for hostname resolution in the home network.
o DHCP Client ID
* The DHCP Client-ID used to obtain the IP address. When the
Mobile Node returns home and is responsible for managing its
own address, if the home address was assigned using DHCP
server, this options maps to the client identifier option as
defined in section 9.14 of [RFC2132] and referenced in
[RFC2131].
o DHCP Server
* The DHCP server's IP address in the home network.
o Configuration URL
* The URL for the Moible Node to download configuration
parameters from a server.
When the Mobile Node needs to obtain its host configuration, the Host
Configuration Request VSE is appended to the Registration Request.
This VSE indicates to the Home Agent that either all or selected host
configuration VSEs need to be appended to the Registration Reply.
The VSEs are authenticated as part of the registration message using
any of the authentication mechanism defined for Mobile IP ([RFC3344],
[RFC3012]).
This message MAY contain extensions defined in Mobile IP, including
vendor specific extensions [RFC3115].
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4. Host Configuration Extensions
The host configuration extensions are based on normal vendor specific
extension type which is skippable during registration processing.
The format is shown below. The Vendor-NVSE-Value contains the
subtype fields.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor/Org-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-NVSE-Type | Vendor-NVSE-Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: 134
Length:
Indicates the length (in bytes) of the data field within this
extension, excluding the Type and Length fields.
Reserved:
Reserved for future use. To be set to 0 while sending, ignored
on reception.
Vendor-NVSE-Type:
9 (cisco)
Vendor-NVSE-Value:
Format is shown below for each subtype.
4.1 Host Configuration Request Extension
This format of the Host Configuration Request extension is shown
below.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type | Selector |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sub-Type:
0
Selector:
0 indicates all host configuration available to the HA is
requested by the Mobile Node.
4.2 Home Network Prefix Extension
This format of the Home Network Prefix extension is shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type | Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sub-Type:
1
Prefix Length:
The number of bits in the home subnet prefix.
4.3 DNS Server Extension
This format of the DNS Server extension is shown below.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type | Primary DNS Server
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . | Secondary DNS Server
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sub Type:
2
Primary DNS Server:
The IP address of the primary DNS server.
Secondary DNS Server:
The IP address of the secondary DNS server.
4.4 DHCP Server Extension
This format of the DHCP Server extension is shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type | DHCP Server
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sub-Type:
3
DHCP Server:
The IP address of the DHCP server.
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4.5 DHCP Client ID Extension
This format of the DHCP client id extension is shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type | Client ID . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sub-Type:
4
Client ID:
DHCP servers use this value to index their database of address
bindings. This value is expected to be unique for all clients
in an administrative domain. The size of field is between 2
and 255 octets.
4.6 Default Gateway Extension
This format of the Default Gateway extension is shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type | Default Gateway
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sub-Type:
5
Default Gateway:
The IP address of the default gateway for the Mobile Node on
the home network.
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4.7 DNS Suffix Extension
This format of the DNS Suffix extension is shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type | DNS Suffix . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sub-Type:
6
DNS Suffix:
The DNS suffix to be appended to the name of Mobile Node when
completing its fully qualified domain name (FQDN). The size of
field is between 1 and 246 octets.
4.8 Configuration URL Extension
This format of the Configuration URL extension is shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type | URL String . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sub-Type:
7
URL String:
The Mobile Node can retrieve configuration parameters via the
URL. The URL is atmost 246 bytes in length.
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5. Security Considerations
The host configuration extensions follow the same rules for Mobile IP
extensions in registration messages. See the Security Considerations
section in RFC 3344.
The Configuration URL extension may trigger the Mobile Node to
download the configuration parameters from a server. The protection
of the data transfer is outside the scope of this document. Possible
options include encryption of data before transfer or using HTTPS.
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6. IANA Considerations
This is an information draft. No IANA actions required.
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7. Acknowledgements
The authors would like to acknowledge Jayshree Bharatia, Kuntal
Chowdhury, Avi Lior, and Lila Madour for their contributions to
Mobile IPv4 Extension for Configuration Options Exchange draft,
draft-bharatia-mobileip-gen-mipv4-ext-02.txt.
8. References
[RFC1332] McGregor, G., "The PPP Internet Protocol Control Protocol
(IPCP)", RFC 1332, May 1992.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
[RFC3012] Perkins, C. and P. Calhoun, "Mobile IPv4
Challenge/Response Extensions", RFC 3012, November 2000.
[RFC3115] Dommety, G. and K. Leung, "Mobile IP
Vendor/Organization-Specific Extensions", RFC 3115, April
2001.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
Authors' Addresses
Kent Leung
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Phone: +1 408-526-5030
Email: kleung@cisco.com
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Alpesh Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Phone: +1 408-853-9580
Email: alpesh@cisco.com
George Tsirtsis
Flarion Technologies
Bedminster One
135 Route 202/206 South
Bedminster, NJ 07921
US
Phone: +1 908-947-7059
Email: g.tsirtsis@flarion.com
Espen Klovning
Birdstep Technology ASA
Bryggegata 7
Oslo, 0250
Norway
Phone: +47 95 20 26 29
Email: espen@birdstep.com
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