[110104] in North American Network Operators' Group
RE: What is the most standard subnet length on internet
daemon@ATHENA.MIT.EDU (Scott Morris)
Wed Dec 24 14:04:59 2008
From: "Scott Morris" <swm@emanon.com>
To: "'Jon Lewis'" <jlewis@lewis.org>,
"'Seth Mattinen'" <sethm@rollernet.us>
Date: Wed, 24 Dec 2008 14:03:38 -0500
In-Reply-To: <Pine.LNX.4.61.0812222009090.6312@soloth.lewis.org>
Cc: 'NANOG list' <nanog@nanog.org>
Reply-To: swm@emanon.com
Errors-To: nanog-bounces@nanog.org
In case anyone cares... From my router's perspective:
/1 0
/2 0
/3 0
/4 0
/5 0
/6 0
/7 0
/8 20
/9 9
/10 20
/11 53
/12 159
/13 310
/14 560
/15 1,096
/16 10,235
/17 4,461
/18 7,593
/19 16,284
/20 19,075
/21 18,598
/22 23,941
/23 24,615
/24 144,832
/25 1
/26 1
/27 1
/28 3
/29 1
/30 1,234
/31 13
/32 23
Total 273,138
No, I wasn't bored enough to count them by hand. JUNOS has a "count"
feature. :)
Scott
-----Original Message-----
From: Jon Lewis [mailto:jlewis@lewis.org]
Sent: Monday, December 22, 2008 8:12 PM
To: Seth Mattinen
Cc: NANOG list
Subject: Re: What is the most standard subnet length on internet
On Mon, 22 Dec 2008, Seth Mattinen wrote:
> Anyone running a platform that can't take a full table would apply
> such a filter to weed out anyone who likes to announce all of their
> space as /24's for "traffic engineering". If one does that and doesn't
> announce the aggregate as well, one could find themselves facing random
black holes.
There's no "if" about it. Months ago when I and others were looking into
this, we found plenty of examples of networks with /19s, /20s, etc.
announcing only the /24 deaggregates. If you plan to filter these people
and have customers to answer to, you'll need to point default at someone
who's not filtering them.
----------------------------------------------------------------------
Jon Lewis | I route
Senior Network Engineer | therefore you are
Atlantic Net |
_________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
