On Jul 17, 2007, at 3:53 PM, Dean Anderson wrote:
Geography doesn't matter very much. I don't connect to the people
across
the street. Bandwidth, latency, traffic do matter, but BGP is path
oriented. Hence we analyze flow data to figure out who we are
exchanging traffic with, and reduce costs to those AS's. Maybe BGP got
it wrong on what is important in a routing decision.
But those costs are driven in large part by geography. E.g.,
local loop across the street v. across town, or backbone link
between two routers in the same POP or between two across
the pond from one another, or a packet traveling between two
customers as opposed to between a transit and bi-lateral or
paid interconnection. Just as applicable as propagation delay, for
that matter.
And if you don't have mechanisms to tie geographical
constructs to network transactional information (i.e., flow data
coupled with control plane information beyond crude AS paths
or next hops alone) then you don't have mechanisms to
determine where, what and how optimal - technically and from
a business perspective, those "higher-layer policies" actually are.
Coupling of control and data plane information helps to enable
this analysis, in particular wrt the intra-domain case, and at least
for identifying and scoping costs based on the ingress and
egress points in the local administrative domain.
-danny
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