[Nanog] Cogent Router dropping packets

John van Oppen (list account) john-lists at vanoppen.com
Mon Apr 21 18:04:19 CDT 2008

Not sure what you are talking about, cogent is all AS174...    Other
than a few odd routers doing DS3 aggregation I don't think there is any
old PSInet network online (other than the AS number and IP addresses).
Cogent integrated acquisitions quite quickly (I was an aleron customer
and it only took two months from the purchase close for us to move from
AS4200 to 174).

As for the two BGP peer question, they do it anywhere where they have
Ethernet distribution, at least as far I can tell.   That being said, we
don't use them anymore since we could not get them to play-ball on
pricing at larger commits either (I won't buy cogent if they don't at
least match the terms of our cheapest large-network transit provider).

John van Oppen
Spectrum Networks LLC
206.973.8302 (Direct)
206.973.8300 (main office)

-----Original Message-----
From: manolo [mailto:mhernand1 at comcast.net] 
Sent: Monday, April 21, 2008 1:03 PM
To: Joe Greco
Cc: nanog at merit.edu
Subject: Re: [Nanog] Cogent Router dropping packets

I do have to say that the PSI net side of cogent is very good. We use 
them in Europe without many issues. I stay far away from the legacy 
cogent network in US.


Joe Greco wrote:
>> Joe Greco wrote:
>>> For those unfamiliar, Cogent has a system where you set up an EBGP
>>> with the Cogent router you're connected to, for the purposes of
>>> your routes into Cogent.  However, these are typically smaller,
>>> class routers, and do not handle full tables - so you don't get your
>>> from that router.  To get a full table FROM Cogent, you need to set
up an
>>> EBGP multihop session with them, to their nearest full-table router.
>>> believe they actually do all their BGP connections in that manner.
>> Depends on the service you purchase. Fast Ethernet seems to be
>> as eBGP-multihop (the first hop is just a L3 switch), however DS-3 is

>> handled as a single BGP session. I'm not sure if GigE or SONET
>> are handled as multihop or not.
> GigE is, though perhaps not in all cases (we had a client buying
> delivered over gigE, which was definitely multihop).
>> Probably all depends what hardware they have at each POP....
> In part, I'm sure.  There is also a certain benefit to having
> throughout your network, and it sometimes struck me that many of the
> working for Cogent had a bit more than average difficulty dealing with
> unusual situation.  This is not meant harshly, btw.  Generally I like
> Cogent folks, but they (and their products) have their faults, just as
> of the competition does.
> It may also help to remember that there's "legacy" Cogent and then
> PSI/etc.  Perhaps there are some differences as a result.
> The more things you can do using the same template, the less difficult
> is to support.  On the flip side, the less flexible you are ...
> ... JG

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