IPv6 multihoming

Siraj 'Sid' Rakhada virtualsid at gmail.com
Mon Feb 7 15:43:03 CET 2011

Hi Henrik,

On 04/02/2011 13:48, Henrik Lund Kramshøj wrote:

> with regards to filtering BGP I will probably follow, be inspired by, the great work from Team Cymru
> such as the filtering recommendations from:
> http://www.team-cymru.org/ReadingRoom/Templates/IPv6Routers/xsp-recommendations.html
> combined with the listings from:
> http://www.space.net/~gert/RIPE/ipv6-filters.html
> in essence, you can probably filter a lot of /48 except the ones from "real PI space", micro allocations
> to root servers, internet exchanges etc.

Looking at the above URLs, I see where it mentions that operators should 
filter prefixes longer than /32 - section 5.2 on Gert's filter page. 
This is something I missed on previous readings!

When initially writing an IPv6 addressing plans, I could not find what a 
common filter was, apart from that a /48 was probably fine (from Gert 
Doering's web page, section 5.1).
 From this, I assumed that if someone were to split a /32 PA range into 
/40s, or longer, it would probably be okay, up til /48. In this 
particular scenario, the origin AS would be different for each range.

I now realise that if anyone is using the 'strict' filters, this won't work.

I'm not sure who is filtering prefixes longer than /32 from PA space - 
would operators who do filter PA space that's longer than /32 be willing 
to point it out? If you plan to change your filters to be more strict, 
that would be useful too.

The few operators I've asked seem to have no policy (yet!).

This is really an information gathering exercise, as I'm finding it 
difficult to find out what operators are actually filtering on, or what 
they intend to actually filter on - PA or PI space wise.



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