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Re: a question about the economics of peering
- From: Nigel Titley
- Date: Fri Nov 30 17:22:45 2001
> On Fri, 30 Nov 2001, David R. Dick wrote:
> :The problem with this idea is that public exchange points need
> :to be *avoided* when they get too congested. People may start
> :out trying to minimize number of hops, but I think they eventually
> :try to minimize total latency.
> Indeed. The notion of "hopcount" is objectively meaningless.
> You can count hops by physical wires, data segments, network hops,
> AS's or combinations of each (MPLS, GRE, PPP etc).
> He may have been trying to suggest the value of having a low
> latency path to a tier-1 provider, who may have low latency
> across their backbone and through their cores.
> But this is what you get with any good ISP, so I don't understand
> what makes IX's more special than being connected to UUNet,
> Exodus, or any other tier-1. In fact, having a connection to
> a tier-1, who may be at many IX's, would leave you with the benefits
> of diverse paths to other networks, without the premium of
> an IX. Especially considering the tier-1 would be doing traffic
> shaping to minimize latency across the backbone.
> Also, I wonder if you can measure latency reliably over time
> for more than 3 or 4 'hops' out, and relative to a small
> number of destinations, before your results cease to be relative
> to each other? I'm sure there is a principle like this acting
> upon the Internet somehow.
> Without latency measurements for the media you are counting hops in,
> you might as well count sheep. I think the engineer mentioned at the
> beginning of this thread was trying to hoodwink and bamboozle you.
I'm stood to one side up to now, but now this thread is drifting over to
I was the engineer in question, and I was most certainly not trying to
hoodwink or bamboozle. Neither am I an ignorant sales-droid, as someone
else has said. Those of you who know me, as I think that a fair number
of people on this list do, will vouch for my honesty, and my pedigree in
I think Alex misunderstood what I was trying to say, and since we were
shouting at each other down a very bad phone line with a loudspeaking
phone at either end, he's got a certain amount of excuse.
Firstly, I've been designing IP networks since the late 80s, and ISPs
since the early 90s. I'm not "fresh out of cable school" to quote one
correspondant. I've set peering policy for at least 2 large ISPs (BTnet
and Level3 (Europe)). Peering is my field of expertise. I'm on the
council of the LINX, which is the biggest peering point in Europe. I've
also got experience of selling internet services in Europe, and to be
frank, the customers over here have different requirements than over in
the US. The first thing you get asked is "how good is your peering".
They then ask you how much private peering you have, despite the fact
that IXPs in Europe tend to be well run and uncongested.
What I was offering him was a LAN extension service. One of the things
you can use this for is to peer with other customers. It looks like a
direct peering (so you keep customers happy) and it gets the bits from A
to C without passing through (possibly congested and oversubscribed) B.
Its not an oversubscribed service, so you get effectively private line
performance. And the costing is distance independent, which makes it
more like a peering point, in charging terms.
Hope this sets the record straight.
Note that I'm posting this from my home email address, and I'm speaking
on my own behalf, not that of my company.
All the best