Internet Engineering Task Force M. Townsley
Internet-Draft O. Troan
Intended status: Informational cisco
Expires: June 9, 2012 December 7, 2011
Basic Requirements for IPv6 Customer Edge Routers - multihoming and
transition
draft-townsley-troan-ipv6-ce-transitioning-00
Abstract
This document specifies general IPv6 multihoming and specific 6rd
transitioning requirements for an IPv6 Customer Edge (CE) router.
Status of this Memo
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1. Introduction
This document defines transitioning and multihoming IPv6 features for
a residential or small office router referred to as an IPv6 CE
router. Typically these routers also support IPv4.
1.1. 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].
2. Terminology
SRIB A Source Address Routing Information Base
containing an entry per delegated prefix.
Each entry points to one or more
Destination Address Routing Tables (DRIB).
DRIB A Destination Address Routing Information
Base used for destination address longest
matching lookups. Each entry points to one
or more next-hops.
3. IPv6 Multi-Prefix Multihoming
A multihomed, multiprefix, IPv6 CE router has multiple WAN interfaces
connecting it to one or more Service Providers. The interfaces may
be "real" or "virtual" in the case of tunneling technology such as
6rd. The CE router receives one or more delegated prefixes, each
associated with one or more WAN interfaces. The CE router has a
single SRIB, and one DRIB associated with each WAN Interface.
WAN interfaces are used to send Ingress traffic from the Internet to
the End-User, and Egress traffic from the End-User network to the
Internet. Ingress traffic may be received on any active interface at
any time. Egress traffic follows a set of rules within the CE in
order to choose the proper WAN interface. This is important not only
in order to choose the best path, but also because the networks that
the CE are connected to typically employ source address verification
mechanisms.
Packets arriving at the CE have an IPv6 source address chosen by the
host [RFC3484]. The SRIB contains an entry for each delegated prefix
with a pointer to one or more DRIBs. A longest matching lookup based
upon the source address of each arriving packet is performed within
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the SRIB to determine the DRIB(s). The egress WAN interface to use
for sending a packet is then chosen by performing a longest matching
lookup within the resulting DRIB(s).
Multihoming requirements:
MH-1: An IPv6 CE router MUST create a separate DRIB for each WAN
interface (real or virtual) and installs a route for the
associated delegated prefix, default route and more specific
routes.
MH-2: An IPv6 CE router MUST create an SRIB containing entries for
associated delegated prefixes. Each entry points to one or
more DRIBs. An entry points to multiple DRIBs only in the
case where an identical delegated prefix is associated with
multiple WAN interfaces.
MH-3: When forwarding a packet from a LAN interface, the CE router
MUST do a longest matching lookup based on the packet's Source
Address in the SRIB. A Destination Address lookup is then
performed in the corresponding DRIB or DRIBs. When there are
multiple equal matches, the route with the lowest cost is
chosen.
4. 6rd Requirements
6RD-1: The IPv6 CE router MUST implement 6rd as defined in
[RFC5969].
6RD-2: The CE MUST support 6rd configuration via the 6rd DHCPv4
Option (212). If the CE router has obtained an IPv4 network
address through some other means (e.g., PPP), it SHOULD use
the DHCPINFORM request message [RFC2131] to request the 6rd
DHCPv4 Option. The IPv6 CE router MAY use other mechanisms
to configure 6rd parameters. Such mechanisms are outside the
scope of this document.
6RD-3: CE routers that support configuration mechanisms (manual,
TR-69, etc.) other than the 6rd DHCPv4 Option 212, SHOULD
support 6rd "hub and spoke" mode. 6rd "hub and spoke" mode
requires all IPv6 traffic to go to the 6rd Border Relay. In
effect, this removes the "direct connect to 6rd" route
defined in Section 7.1.1 of [RFC5969].
6RD sunsetting requirements:
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6RDS-1: Multihoming as defined in section Section 3 MUST be
supported, allowing 6rd and native packets to be sent and
received as long as 6rd configuration is provided by the
ISP.
6RDS-2: By default, the 6rd virtual interface MUST be assigned a
higher routing cost than a native IPv6 interface.
6RDS-3: The IPv6 CE router MUST support that 6rd and native IPv6
delegated prefixes are identical or different, and operate
as defined in the multihoming section.
5. Security Considerations
6. Acknowledgements
7. IANA Considerations
This memo includes no request to IANA.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification",
RFC 5969, August 2010.
8.2. Informative References
[RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC6204] Singh, H., Beebee, W., Donley, C., Stark, B., and O.
Troan, "Basic Requirements for IPv6 Customer Edge
Routers", RFC 6204, April 2011.
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Authors' Addresses
Mark Townsley
cisco
Email:
Ole Troan
cisco
Email:
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