That is of limited usefulness. 1) They'd all have to have the same next hop. 2) you would have to hear all three /24's of them from all your peers, all with the same next hop, metrics, med, etc. Otherwise the aggregate route becomes the backup route for other, more specific announcements of the /24 that you can't aggregate. It would be nice for the single homed, but then why are you running bgp? Nathan Alexander NMC Shift Manager 703/363-5293(office) 301/442-8695(cell) 877/541-2189(pager) Nathan.Alexander@qwest.com - Internal Use Only - Disclose and Distribute only to Qwest Employees and authorized persons working for Qwest. Disclosure outside of Qwest is prohibited without authorization.

-----Original Message----- From: Ralph Doncaster [mailto:ralph@istop.com] Sent: Friday, July 19, 2002 8:07 AM To: Richard A Steenbergen Cc: nanog@merit.edu Subject: Re: /24s run amuck... again

On Fri, 19 Jul 2002, Richard A Steenbergen wrote:

...

With all the recent talk about filtering, I figured now was a good time to update my list of evil /24 announcers... There are currently over 63k /24s out of 113k total unfiltered announcements (over 55%).

Does anyone (Cisco, Juniper, etc.) have an auto-aggregation feature? Let's say a router that receives the following prefixes under a single AS 206.51.128.0/24 206.51.129.0/24 206.51.131.0/24

And the following network is not in the table: 206.51.130.0/24

Then it would be usefull to collapse it into a single 206.52.128/22 aggregate (especially if the metrics & communities are the same).

-Ralph