a question about the economics of peering

batz batsy at vapour.net
Fri Nov 30 18:16:30 UTC 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. 

Reluctant Ninja
Defective Technologies

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