[ipv6-wg] Multihoming in IPv6 using PA space

[Going out to routing-wg and ipv6-wg, trim as needed in follow-ups]

Before the last IETF meeting there was some discussion about the  
difficulties in multihoming using a prefix out of PA space from an  
ISP in IPv6. Because many ISPs filter at /32 or /35 in IPv6, the /48s  
(or /56s) used for multihoming are often filtered out. After some  
discussion with people from the IETF v6ops wg, I've written the draft  
mentioned below, outlining the problem and proposing a BGP community  
to tag the prefixes used for this so they can be un-filtered as needed.

Feedback from people involved with and/or an interest in IPv6 routing  
is highly appreciated. I'd be happy to discuss the draft in either  
the routing or IPv6 wgs, or talk about it briefly at the end of my  
IPv6 routing tutorial on wednesday morning. And of course one-on-one  
in the hallway.

The -01 with only minor changes should be up soon, or you can find it  
at http://www.muada.com/drafts/draft-van-beijnum-v6ops-pa-mhome- 
community-01.txt

Begin forwarded message:
> A New Internet-Draft is available from the on-line Internet-Drafts
> directories.


> 	Title		: BGP Community for PA Multihoming
> 	Author(s)	: I. van Beijnum
> 	Filename	: draft-van-beijnum-v6ops-pa-mhome-community-00.txt
> 	Pages		: 8
> 	Date		: 2006-9-11

> When an organization wants to connect to the internet using two or  
> more
> Internet Service Providers (multihoming), this is usually done by
> setting up BGP routing between the organization in question and  
> each of
> its ISPs. For this, the multihomed organization needs a block of  
> address space. This can either be a provider independent (PI)  
> address block that belongs to the organization, or a block out of  
> the provider aggregatable (PA) address space of one its ISPs.

> With IPv4, an address block of at least /24 will generally be suitable
> for multihoming, whether its origin is PI or PA. However, until now,
> ISPs were encouraged to only accept /32 prefixes from IPv6 PA space,
> while end-users generally receive a /48. This makes multihoming  
> with PA
> address space in IPv6 very difficult. This memo describes a new
> well-known BGP community attribute for tagging prefixes used for
> multihoming with PA space in order to facilitate filtering, rather  
> than
> filter based on prefix length alone.


> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-van-beijnum-v6ops-pa- 
> mhome-community-00.txt