[nycbug-talk] Cogent and Sprint - a signal of things getting Oldschool?

Alex Pilosov alex at pilosoft.com
Fri Oct 31 20:13:59 EDT 2008

On Fri, 31 Oct 2008, Charles Sprickman wrote:

> Nice.
> I've not followed the ups and downs of ISP dramas in a long time, but my
> gut feeling, even before reading the Renesys blog, was "oh, sprint still
> sells internets?".  Personally, I think this hurts Sprint the most.  My
> gut feeling is that they are something of a has-been in this market.
It's complicated. Despite being a "has-been", sprint maintains the "we
will not peer with you" reputation, and is the "hardest to establish
settlement-free peering" carrier. As a result, many people end up using
only Sprint for transit (or, "the only transit we will admit to having"),
so they *can* get other peering (it's a bit complicated - basically, if
your transit is an existing peer, you won't get peering), in effect,
helping Sprint maintain this status.

> One thing that really has me wondering, and again, this is probably an 
> Alex question, is an odd situation I ran into a few years back...  I was 
> toying around with two providers - L3 and HE.  I primarily wanted HE as 
> backup, since L3 was not really soaking us and they generally have their 
> shit together outside of the management/sales/install realms.  No matter 
> how much I prepended our HE announcement, I just could not squash the 
> inbound traffic.  Apparently HE buys transit from Cogent and there are a 
> TON of people that shove all outbound traffic down a Cogent link if they 
> have one.  This is not that much of a surprise (the volume of traffic was 
*snicker* Yes, cogent is the "transit we use for outbound but we won't
admit to it".

The answer, of course, is not prepending it, but setting community flags 
telling HE to not announce this route to cogent, or to depreference your 
route while announcing to cogent, or some such. I don't know the community 
list for HE.

> though), but the thing that puzzled me when I ran a bunch of stuff
> through flow-tools was that I was seeing traffic from 1239 (Sprint)
> coming in through HE via Cogent.  I'm still puzzled as to what that was
> about - from my view, it looked like Sprint jamming traffic down Cogent
> rather than L3 (I'm certain Sprint and L3 peer).
It's complicated without looking at more details. You can't say where it 
*really* came from. What *could* be easily happening is that someone (X) 
only uses Sprint for inbound - so you see them behind Sprint. However, 
X uses everyone else for outbound (including Cogent), who will obviously 
send it toward HE (paying customer).

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