[36585] in North American Network Operators' Group
Re: Getting a "portable" /19 or /20
daemon@ATHENA.MIT.EDU (Sean M. Doran)
Wed Apr 11 00:40:12 2001
To: gmaxwell@martin.fl.us, msa@samurai.sfo.dead-dog.com
Cc: nanog@merit.edu
Message-Id: <20010411023812.C79E3C7910@cesium.clock.org>
Date: Tue, 10 Apr 2001 19:38:12 -0700 (PDT)
From: smd@clock.org (Sean M. Doran)
Errors-To: owner-nanog-outgoing@merit.edu
Greg Maxwell <gmaxwell@martin.fl.us> writes:
| > Aggregation buys time, that's it. Aggregation does not make the
| > current routing methods any more scalable.
|
| In IPv4 yes, because you can't have perfect aggregation, too much network
| multihoming and old prefixes and it's to painful to change address blocks.
|
| In IPv6, if implimented right aggregation provides for virtually limitless
| scalability for unicast traffic.
Perfectly aggregated networks are star-shaped.
Any more complicated topology cannot be perfectly aggregated.
In real networks, aggregation at best follows a "reasonable"
trade-off between optimizing and stabilizing route selection.
Not everyone will agree on what is a "reasonable" balance.
Result: some people unhappy about suboptimal routing ("my packets
to my neighbour across the street go through another country") and
some people unhappy about too-great dynamicism ("damn, time to upgrade
to a faster processor, more memory, faster memory, etc etc etc").
This is a result of the CIDR addressing architecture and is
INDEPENDENT OF THE NUMBER OF BITS IN AN ADDRESS.
Sean.
