[jump-admins] Routing problems to www.eurovision.tv 2400:CB00::/32 CLOUDFLARE

James A. T. Rice admins at jump.net.uk
Fri Jun 15 19:02:17 CEST 2012

Hi Tom,

On Fri, 15 Jun 2012, Tom Paseka wrote:

> CloudFlare operates a discontiguous network and we are unable to announce the /32.

route-views shows you using the same upstreams for each /48, in fact, all 
of the bgp attributes seem identical for each /48 that you announce.

There is no reason why you can't announce a /32 to your upstreams, and 
then steer traffic to your discontiguous sites with /48s (preferably 
tagged with no-export on the /48s).

> The /48 is a valid announcement for the global table.

That's bogus. You could say the same that /32 is a valid announcement for 
IPv4 table. It doesn't help.

> While we understand there are some concerns about de-aggergation

/48 was designed as the size of an 'end user' assignment, so opening 
filters to accept /48 across the v6 space is similar to accepting that 
each end user on the internet can have a place in the global tables. This 
is clearly not plausible.

> aggregation is not possible and we would either be announcing the 
> deaggregated address space from a single assignment, or we'd have 
> multiple assignments for the same purpose, so the impact on the routing 
> table would be the same.

Some level of deaggregation can be seen as reasonable, you could announce 
your /32 as a /36 per site, assuming 16 sites is sufficient and most sites 
will accept this, or a bunch of /40s if 256 sites is required. Even so 
announcing the /32 covering route is desirable too.

Announcing as /48s is a deaggregation ratio of 65536 times. This is 
ridiculous. In the same way that you wouldn't try to announce a IPv4 /16 
as individual IPv4 /32s (which is exactly the same deaggregation amount 
that you are doing here).

> If the full table can not be accepted, I would recommend installing a 
> default route to one or all of your upstreams, otherwise many parts of 
> the global table will not be reachable, not just to CloudFlare. 

That breaks resilience. Lots of the internet would rather have known 
resilience and breakage to places announcing incorrectly, rather than rely 
on defaults.

If you need help with fixing this on your side there is plenty of clue on 
this list. At the moment the ghost route hunter shows you're lacking 
connectivity to many major sites - if others can get it right I'm sure you 
can too.


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