nanog mailing list archives

Re: Internet diameter?


From: Ross Tajvar <ross () tajvar io>
Date: Wed, 21 Nov 2018 23:41:52 -0500

I’m not sure on what use this data, if collected, would be. Latency is
the most important.
It's not operationally useful in any way that I can think of, but it is
interesting (at least to me). It's possible that Bill has something in
mind, though.

[...] which is more meaningful a metric, AS-path or hop count?
Good point. Before we can decide which is more useful, we have to decide
what they would be useful for.
But, I think it's not really feasible to analyze hop count, because you
would have to collect that data with a huge number of traceroutes.
Average/median AS-path length can be estimated by static analysis of BGP
tables from various routers.

Many networks have a large number of routers but the packets don’t stay
in them very long.
It wouldn't be a very good router if the packets hung around for a long
time before leaving :)

On Wed, Nov 21, 2018 at 11:26 PM Ben Cannon <ben () 6by7 net> wrote:

This begs the question, which is more meaningful a metric, AS-path or hop
count?  Many networks have a large number of routers but the packets don’t
stay in them very long.

-Ben.


On Nov 21, 2018, at 8:10 PM, Bryce Wilson <bryce () thenetworknerds ca>
wrote:

I don’t have any hard statistics but I notice that on a majority of ASs on
bgp.he.net, the average AS path length is between 4 and 5. As for the
average number of hops, it clearly depends on what type of traffic and many
ASNs have more than one router. Going on my own experience I would say
between 8 and 10 hops would be the average of non-cached content. If you
included cached content such as cdns and caches then the actual average
might be closer to 5 to 7. This is only an estimate from my own network and
those of my clients so the actual value may be completely different.

As with what others have said, I’m not sure on what use this data, if
collected, would be. Latency is the most important.


Thanks ~ Bryce Wilson, AS202313, EVIX, AS137933




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