topological closeness....

The only problem that it does not work at all.

Which WWW server is closer to me - one with BGP path

1239 3491 690 1333 (

or one at

1239 1792 (

The second is in China, for God's sake!

There ain't no such thing as global metrics. The only
useful kind of metrics is administrative, and therefore
they cannot reflect any real characteristics of paths.

On a global level, how useful would it be to base the decision
on whether the client address belongs to the the InterNIC block,
APNIC or the european registry ? I can live with exceptions
such as an MCI customer in India gets redirected to the
north american mirror server instead of the one in Singapore
because their address belongs to an InterNIC allocated MCI
block. How often do these exceptions happen ? Where can I
find the association of address blocks and registries ?

We are currently working on mirroring a copule of sites on all
major continents. I understand this approach does not optimize
routing to the web servers within north america.


I don't have any statistics on geographical exceptions, but the allocation
of IPv4 space by the IANA is available at

// Matt Zimmerman Chief of System Management NetRail, Inc.
// (703) 524-4800 [voice] (703) 524-4802 [data] (703) 534-5033 [fax]