|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Cisco Route filtering [was Re: OPS: BGP spew from ASN 7374]
I've had a question on this for some time that maybe can get answered here. Let's assume for a moment that I have a network of 209.123/18 (1/4 of a classful B). Let's further assume that my upstream filters me with: access-list 2002 permit ip host 209.123.0.0 host 255.255.0.0 neigh 2.3.4.5 distrib 2002 in Will my /18 announcement make it through this /16 filter? Would the same be true with a prefix-length filter, which I assume the syntax would be: ip prefix-list 1 permit 209.123.0.0/16 neigh 2.3.4.5 prefix-list 1 in Thanks. On Wed, 7 Apr 1999, R.P. Aditya wrote: > > This should probably be moved to cisco-nsp if it gets any more in-depth, > however: > > > Cisco: could we please have more config memory, so we can load access-lists > > for even huge BGP peers? > > Although you're probably asking for exactly what you say, config memory, it > might also be useful to use prefix-lists to filter routing announcements: > > http://www.academ.com/nanog/june1998/turner/sld014.htm > > and the notes on bug CSCdk93005 seem to indicate that prefix-lists do make a > difference and should be used over access-lists for filtering routes... > > Hope that helps, > Adi > > -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Atheism is a non-prophet organization. I route, therefore I am. Alex Rubenstein, [email protected], KC2BUO, ISP/C Charter Member Father of the Network and Head Bottle-Washer Net Access Corporation, 9 Mt. Pleasant Tpk., Denville, NJ 07834 Don't choose a spineless ISP; we have more backbone! http://www.nac.net -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
|