Cogent and Google no longer peered via IPv6

Frank Bulk frnkblk at
Wed May 4 19:15:49 CEST 2011

I misinterpreted our upstream networking guy's response -- we get 15169 via Sprint.  So that's consistent with your experience.

Any way to find out when Google de-peered with Cogent?  I'm sure Renesys has that kind of data.


-----Original Message-----
From: Tore Anderson [mailto:tore.anderson at] 
Sent: Wednesday, May 04, 2011 8:30 AM
To: frnkblk at
Cc: 'Martin Millnert'; 'Phil Benchoff'; ipv6-ops at
Subject: Re: Cogent and Google no longer peered via IPv6

* Frank Bulk

> Yes, we're receiving 15169 from Cogent.

Hi Frank,

In Oslo we don't:

tore at cr2> show route aspath-regex 174.*15169.* table inet6.0 all

inet6.0: 5570 destinations, 11272 routes (5569 active, 0 holddown, 1 hidden)

tore at cr2>

Traceroutes from all PoPs available at
<> to's
IPv6 address all result in a !H error. Where do you take transit from
them from?

I opened a ticket with them about it and so far I've only gotten a
boiler-plate answer that does not at all shed any light on the
situation, considering that they used to carry those routes before.

So either there's some kind of technical problem going on, or one
network depeered the other. Considering that Cogent seems unable or
unwilling to give a clear answer, I have my suspicions...

* eu-support at

> You have enquired with Cogent Support about missing routes in the
> IPv6 routing table provided to you by Cogent as part of your Internet
> service. We understand your concerns and would like to provide you
> with additional information on the matter.
> As you know, the Internet is made up of tens of thousands of networks
> which must be interconnected, either by means of direct peering
> between individual networks, or by connection to upstream transit
> providers.  For IPv4 routes, the Internet follows these
> interconnection rules and enables transit providers (such as Cogent)
> to provide a full global IPv4 routing table to their customers. IPv6
> interconnection, on the other hand, has not yet reached this level of
> maturity.
> Like other providers, Cogent is actively expanding its IPV6 routing
> table.  This is not always easy due to the fact that certain networks
> do not announce the IPV6 routes of their customers to their upstream
> providers. Hence such IPv6 routes are not visible to the entire
> Internet.  As a result, no network in the world can claim to provide
> a full global routing table to its customers. Cogent remains
> confident that IPv6 interconnection will gradually attain the same
> level of maturity as IPV4. In the mean time, Cogent is continuously
> working on improving global IPv6 connectivity by adding new IPv6
> routes to its network on a daily basis and collaborating with the
> Internet carriers' community to achieve ubiquitous IPv6 coverage
> Cogent Support remains at your disposal for any subsequent questions
> you may have.

Tore Anderson
Redpill Linpro AS -
Tel: +47 21 54 41 27

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