Routing problems to 2400:CB00::/32 CLOUDFLARE

Bjoern A. Zeeb bzeeb-lists at
Fri Jun 15 22:30:34 CEST 2012

On 15. Jun 2012, at 16:49 , Daniel Roesen wrote:

> On Fri, Jun 15, 2012 at 09:42:33AM -0700, Tom Paseka wrote:

>> CloudFlare is not the only provider using routing like this, without an
>> aggregate matching the minimum allocation size.
> It's certainly not done on any significant scale, otherwise we would
> have heard more often from such problems here on the list.

I had done it from 2006 to 2008 while still doing a real v6 network at
and ISP.  I hadn't used Gert's (relaxed) BGP filters but done exactly
what a lot of people thankfully seem to do, generated the lists according
to RIR data.  See the bottom of this *old* page:

Back then the difference between routes and received routes had been
significant already, which was the really bad thing.
Of course (as you can see) I had only found one real problem, which
RIPE refused to adjust the data for (as they had done for others it

I'd love to update these filters again and run statistics but I am sure
there are people out there doing it already now and doing a better job.
Otherwise I'd need unfiltered full feeds from a couple of places or use
the dumps provided by some entities for stats.  It had been a shell
script to fetch the data, and about 40 lines of Perl to generate the ruleset
and once in a while the need to add a new block.  I might even still have
a copy somewhere.

As I had said back then:  this ain't be v4 and a big +1 from me for
everyone doing *strict* filtering with IPv6 to stop the silliness at the
"beginning", esp. given RIRs are handing out micro allocations these days
for those who really need them.  Whether some people do or don't need them,
is a totally different (policy) discussion.

/bz, having migrated a /48 v6 network on a friday afternoon to a new
prefix before going to the airport and finished the job only a week later
retiring the old prefix entirely.  You can do it, even with customers
(inhouse or external) and it's not really been painful either.

Bjoern A. Zeeb                                 You have to have visions!
   It does not matter how good you are. It matters what good you do!

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