IPv6 martian filtering (some /48s should be permitted) and SiXXS GRH

Mon Nov 1 15:03:06 UTC 2004

On 1 Nov 2004, at 05:40, JP Velders wrote:

> A nice and handy tool to see if something is being propagated and/or
> filtered is the SixXS.net GRH Tool which allows prefix comparison(s):
>
> http://www.sixxs.net/tools/grh/compare/? 
> when=current&format=html&a=2001:503:a83e::/48&b=2001:500::/48
> (not much sense, since the AS's differ ;D)

Jeroen Massar pointed me at GRH after my last post, too. Having tried  
some of the tools therein, I highly recommend them.

F-root has its own ARIN assignment (2001:500::/48) as mentioned before,  
but ISC also has a separate allocation which is used for all its other  
activites: 2001:4f8::/32. Using that same path comparison tool to  
compare propagation of those two prefixes provides a good illustration  
of import filtering problems:

http://www.sixxs.net/tools/grh/compare/?a=2001:500::/48&b=2001:4f8::/32

There are lots of GRH participants who see the /32, but who don't see  
the /48 at all. There are also people who see different paths for each  
advertisement, which suggests that they are not being allowed to  
propagate in the same directions.

(There are also some anycast artificats in there; 2001:500::/48 is  
anycast from various places, and hence shorter paths for 2001:500::/48  
vs. 2001:4f8::/48 are to be expected in some cases.)

   http://www.space.net/~gert/RIPE/ipv6-filters.html

Joe