RE: What is the most standard subnet length on internet

["Scott Morris" <swm () emanon com>]

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.

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  Jon Lewis                   |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
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