Re: Peering versus Transit

[Barney Wolff <barney () databus com>]

> From: Sean Doran <smd () cesium clock org>
> Date: Sun, 29 Sep 1996 23:41:28 -0800
>
> In one hypothetical case, consider a large provider that
> is being dumped upon by another provider which is
> outraged that the large provider consistently refuses to
> peer with them.  This could have the result of pushing
> traffic inbound towards the larger provider over the
> threshold at which the difficulties in buffer management
> become highly noticeable, which leads to some 15% packet
> loss at times for customers of the larger provider trying
> to make use of that exchange point.

(Leaving out the over-the-water case for the moment)

I don't understand.  Let's hypothesize an exchange point at which NSPs
S, M, U all meet and peer, and which also includes N, the new provider
who buys transit from U and somehow (How?  Maybe by peering with M) has
a router on the switching fabric at the exchange point.

Packets from N for S's customers therefore are supposed to flow from
N's router to U's router to S's router, yes?  One day, N decides to
save the double hop through the switching fabric, and puts in a static
route for (some of) S's customers so that packets flow directly from
N's router to S's router.  Certainly this is unauthorized.  But how
has the rate of packets into S's router changed?  Moreover, the return
path is still S->U->N, so there's no reason to expect that the packet
rate through S's router will be different in and out.

All this would be quite different if N pointed default to S, I agree.
It would also be different if for some reason S did not advertise all of
its customer routes to U's router at this particular exchange point.  Is
that actually done, and is this relevant to the over-the-water case?

Barney Wolff  <barney () databus com>
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