On 29 Nov 2007, at 22:05, Eduardo Ascenco Reis wrote:
Although the BGP data is around one month old and the original
focus was on Brazilian AS and IP prefixes, the general analysis
covers all Regional Internet Registries (RIRs).
[...]
The methodology shows a good efficiency (around 40%) reducing BGP
table size, but the estimated number of affect prefixes are also
high (around 30%).
This is an interesting piece of work, and highlights an interesting
model (40% table size saving hurts 30% of traffic.)
I have a couple of thoughts:
from the text:
Although representing less than 1% of all suboptimal and
unreachable prefixes, /20 prefixes call attention because of their
mask size to be expected as normal. In this experiment all /20
affected prefixes are from 2 RIPE CIDR (62/8 and 212/7) with /19
longest prefix, which data could eventually be used by RIPE to
reviews these CIDR policy allocations. This is only one use example
of applications that can be derived from analysis like this one.
Do you still have the lab setup ? Could you work out what happens to
the routing table and traffic routing if you permit one deaggregation
per rir prefix ? I.e. This /19 is permitted to become two /20s, but
it is not permitted to become four /21. My desire would be to see
the resolved routing table look almost as trim as your 40% saving,
but a significant amount of traffic routed as intended by the
originating network.
Lastly, perhaps another comment for your recommendations and
conclusions section could be that traffic is hurt most in this model
for networks who deaggregate most. Lets encourage people who read
this document to infer that aggregating their prefixes would improve
their reach in the post 250k routing table world.
Andy
