[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