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

  • From: Joe Abley
  • Date: Mon Nov 01 10:05:21 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