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_________