Re: What is the most standard subnet length on internet

* Patrick W. Gilmore · * Fri Dec 19 23:37:51 2008

On Dec 19, 2008, at 10:48 AM, Joe Greco wrote:
As for routing table size, no router which can handle 10s of Gbps is
at all bothered by the size of the global table,

... as long as it isn't something like a Cisco Catalyst 6509 with
SUP720

and doesn't have a PFC3BXL helping out ...
... or if we conveniently don't classify a Catalyst 65xx as a router

because it was primarily intended as a switch, despite how ISP's
commonly

use them ...
so only edge devices

or stub networks are in danger of needing to filter /24s. And both
of

those can (should?) have something called a "default route", making
it

completely irrelevant whether they hear the /24s anyway.

A more accurate statement is probably that "any router that can handle

10s of Gbps is likely to be available in a configuration that is not
at

all bothered by the current size of the global table, most likely at
some

substantial additional cost."

Good point! I should have said "10s of Gbps and tables associated
with default-free networks".
Or are there lots of people using 6500s without 3BXLs in the DFZ? I
admit I have not audited every router in the DFZ, so perhaps someone
with factual info can help out here.
If not, then we're back to where we started. The DFZ isn't worried
about table size this cycle, and the edges can (should?) have
default. I'm sure that will change in a couple years, but everything
always does.
Oh, and before anyone jumps all over me, I am NOT implying you should
deaggregate and blow up the table. Just that 300K prefixes is the DFZ
is not a reason to start filtering /24s. Today. :)
--
TTFN,
patrick