Re: BellSouth prefix deaggregation (was: as6198 aggregation event)

[Jared Mauch <jared () puck Nether net>]

On Sun, Oct 12, 2003 at 01:02:57PM +0000, Stephen J. Wilcox wrote:
> > Can anyone from BellSouth comment?  What if a few other major ISPs were
> > to add a thousand or so deaggregated routes in a few weeks time?  Would
> > there be a greater impact?
>
> one word - irresponsible

        This clearly stands out to me as a reason to keep and use
prefix filtering on peers to reduce the amount of junk in the routing
tables.  If bellsouth needs to leak more specifics for load balancing
purposes, fine, just make sure those routes don't leave your upstreams
networks and waste router memory for the rest of us that don't need to
see it.

        - Jared

> > (Note: The above numbers are based on data from cidr-report.org.  Some
> > other looking glasses were also checked to see if cidr-report.org's view
> > of these AS's is consistent with the Internet as a whole.  This appears
> > to be the case, but corrections are welcome.)
> >
> > -Terry
> >
> > > -----Original Message-----
> > > From: owner-nanog () merit edu [mailto:owner-nanog () merit edu] On 
> > > Behalf Of Terry Baranski
> > > Sent: Sunday, October 05, 2003 3:01 PM
> > > To: 'James Cowie'; nanog () merit edu
> > > Subject: RE: as6198 aggregation event
> > >
> > >
> > >
> > > James Cowie wrote:
> > >
> > > > On Friday, we noted with some interest the appearance of more 
> > > > than six hundred deaggregated /24s into the global routing 
> > > > tables.  More unusually, they're still in there this morning.  
> > > >
> > > > AS6198 (BellSouth Miami) seems to have been patiently injecting 
> > > > them over the course of several hours, between about 04:00 GMT 
> > > > and 08:00 GMT on Friday morning (3 Oct 2003).  
> > >
> > > If you look at the 09/19 and 09/26 CIDR Reports, BellSouth Atlanta
> > > (AS6197) did something similar during this time period -- they added
> > > about 350 deaggregated prefixes, most if not all /24's.  
> > >
> > > > Usually when we see deaggregations, they hit quickly and they
> > > > disappear quickly; nice sharp vertical jumps in the table size.
> > > > This event lasted for hours and, more importantly, the prefixes 
> > > > haven't come back out again, an unusual pattern for a single-origin
> > > > change that effectively expanded global tables by half a percent. 
> > >
> > > That AS6197's additions are still present isn't encouraging.
> > >
> > > -Terry

-- 
Jared Mauch  | pgp key available via finger from jared () puck nether net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.