Cogent input

manolo mhernand1 at
Thu Jun 11 14:49:23 UTC 2009

Stephen Kratzer wrote:
> Should have said "And, they have no plans to deploy IPv6 in the immediate 
> future."
> On Thursday 11 June 2009 10:33:25 Stephen Kratzer wrote:
>> We've only recently started using Cogent transit, but it's been stable
>> since its introduction 6 months ago. Turn-up was a bit rocky since we never
>> received engineering details, and engineering was atypical in that two eBGP
>> sessions were established, one just to advertise loopbacks, and another for
>> the actual feed. The biggest issue we have with them is that they don't
>> allow deaggregation. If you've been allocated a prefix of length yy,
>> they'll accept only x.x.x.x/yy, not x.x.x.x/yy le 24. Yes, sometimes
>> deaggregation is necessary or desirable even if only temporarily.
>> And, they have no plans to support IPv6.
>> "Cogent's official stance on IPv6 is that we will deploy IPv6 when it
>> becomes a commercial necessity. We have tested IPv6 and we have our plan
>> for rolling it out, but there are no commercial drivers to spend money
>> to upgrade a network to IPv6 for no real return on investment."
>> Stephen Kratzer
>> Network Engineer
>> CTI Networks, Inc.
>> On Thursday 11 June 2009 09:46:45 Justin Shore wrote:
>>> I'm in search of some information about Cogent, it's past, present and
>>> future.  I've heard bits and pieces about Cogent's past over the years
>>> but by no means have I actively been keeping up.
>>> I'm aware of some (regular?) depeering issues.  The NANOG archives have
>>> given me some additional insight into that (recurring?) problem.  The
>>> reasoning behind the depeering events is a bit fuzzy though.  I would be
>>> interested in people's opinion on whether or not they should be consider
>>> for upstream service based on this particular issue.  Are there any
>>> reasonable mitigation measures available to Cogent downstreams if
>>> (when?) Cogent were to be depeered again?  My understanding is that at
>>> least on previous depeering occasion, the depeering partner simply
>>> null-routed all prefixes being received via Cogent, creating a blackhole
>>> essentially.  I also recall reading that this meant that prefixes being
>>> advertised and received by the depeering partner from other peers would
>>> still end up in the blackhole.  The only solution I would see to this
>>> problem would be to shut down the BGP session with Cogent and rely on a
>>> 2nd upstream.  Are there any other possible steps for mitigation in a
>>> depeering event?
>>> I also know that their bandwidth is extremely cheap.  This of course
>>> creates an issue for technical folks when trying to justify other
>>> upstream options that cost significantly more but also don't have a
>>> damaging history of getting depeered.
>>> Does Cogent still have an issue with depeering?  Are there any
>>> reasonable mitigation measures or should a downstream customer do any
>>> thing in particular to ready themselves for a depeering event?  Does
>>> their low cost outweigh the risks?  What are the specific risks?
>>> Thanks
>>>   Justin
In Europe they have been good and stable most of the time. In the US
well, they are cogent and I have so many bad experiences with them here
I cannot in all honestly recommend them. But if your looking for cheap
bandwidth to complement another provider its not an unreasonable thing
to do as they price point is competitive.


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