6to4 DHCP Router Option
draft-andrews-v6ops-6to4-router-option-00

Abstract

Provides a DHCP 6to4 Relay Router option.

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 November 10, 2011.

Copyright Notice

Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

• 1. Introduction
• 2. 6to4 Relay Router Option
• 3. IANA Considerations
• 4. Security Considerations
• 5. References
• Author's Address

1. Introduction

Using 6to4 [RFC 3056] currently requires manual configuration of the relay router or the use of a anycast relay router [RFC 3068]. The latter has a number of well known issues (add reference).

This document attempts to address some of those issues by providing a method for clients to discover the address of a 6to4 relay router. It is expected that the 6to4 relay router will be managed and that it will be topologically close to the client thereby reducing some of the issues with using public anycast relay routers.

Additionally not all IPv4 address allocated to clients are suitable for use with 6to4. Whether they be [RFC 1918] address, or other addresses behind a NAT, or are behind a firewall which blocks 6to4 encapsulted traffic. This document provides a method for the DHCP server operator to signal that the address being returned is not suitable for use with 6to4.

2. 6to4 Relay Router Option

The 6to4 DHCP relay option has code TBD and consists of a single IPv4 address specifing the IPv4 address of the 6to4 relay router. Setting the relay router address to 0.0.0.0 indicates that 6to4 will not work for returned lease address.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      TBD      |       4       |          relay router         ~
   +---------------+---------------+---------------+---------------+
   ~            address            |
   +-------------------------------+
	

3. IANA Considerations

IANA is requested to allocate a DHCP option code point.

4. Security Considerations

A rogue DHCP server advertising this option can cause 6to4 traffic to be redirected anywhere in the world.

Setting the returned address to 0.0.0.0 can be used to deny 6to4 service when it would otherwise work.

5. References

Author's Address