From: keith tokash (ktokash@hotmail.com)
Date: Sat Dec 29 2007 - 18:15:47 ART
High-end gear like 6500s with a Sup720 process acls in TCAMs, removing the CPU
burden. I know that gear is miles away from what the lab uses, but hardware
vs software processing is platform-specific, therefore isn't that clear-cut.
Overall though, if someone said to use the less processor-intensive method I
would go with prefix-lists.
With a few exceptions, secrecy is deeply incompatible with democracy and with
science.
--Carl Sagan
> From: jim@tgasolutions.com
> To: nhatphuc@gmail.com; joe@affirmedsystems.com
> CC: ccielab@groupstudy.com
> Date: Sat, 29 Dec 2007 08:32:18 -0500
> Subject: RE: BGP suppress maps
>
> So in the end, either should be acceptable unless the task says something
like
> this:
>
>
> 1. Filter the (incoming,outgoing ) routes with the least processor
> intensive method.
>
> 2. Filter the (incoming,outgoing ) routes in a manner that does not
use
> a prefix list.
>
> 3. Filter the (incoming,outgoing ) routes in a manner that does not
use
> an access list.
>
>
> Thoughts?
> jim
> From: nhatphuc [mailto:nhatphuc@gmail.com]
> Sent: Saturday, December 29, 2007 3:38 AM
> To: Joseph Brunner
> Cc: Jim McBurnett; ccielab@groupstudy.com
> Subject: Re: BGP suppress maps
>
> Ah, yes. So you have to understand what ACL and prefix-list can match:
>
> A prefix-list cannot be used to match on arbitrary bit patterns like an
> accesslist can. Prefix-lists cannot be used to check if a number is even or
> odd, nor check if a number is divisible by 15, etc... Bit checking in a
> prefix-list is sequential, and must start with the most significant
(leftmost)
> bit. (from IEWB)
>
> Phuc
> On Dec 29, 2007 3:26 PM, Joseph Brunner
> <joe@affirmedsystems.com<mailto:joe@affirmedsystems.com>> wrote:
> Actually that's not true. Prefix-lists can't filter odd/even networks
> ACL's can, while matching prefix length.
>
> Prefix-lists are rumored to be friendlier on the CPU though...
>
> ;)
>
> -----Original Message-----
> From: nobody@groupstudy.com<mailto:nobody@groupstudy.com>
> [mailto:nobody@groupstudy.com<mailto:nobody@groupstudy.com>] On Behalf Of
> nhatphuc
> Sent: Saturday, December 29, 2007 3:02 AM
> To: Jim McBurnett
> Cc: ccielab@groupstudy.com<mailto:ccielab@groupstudy.com>
> Subject: Re: BGP suppress maps
>
> I think there's no difference in using Prefix-list and access-list for BGP
> filtering. As long as you can match the route, both will be OK.
>
> For me, I prefer prefix-list over access-list because it is built to match
> prefixes.
>
> Phuc
>
> On Dec 28, 2007 9:15 AM, Jim McBurnett <
> jim@tgasolutions.com<mailto:jim@tgasolutions.com>> wrote:
>
> > Ok,
> > I am working on BGP suppress maps and keep going back to the difference
> > between prefix lists and standard ACLS on the route map.
> > Both work.
> >
> > I would assume that if the task does not specifically state that you use
> > prefix lists or does not say do not use an access-list, that it is fine.
> >
> > But am I missing some larger picture due to my foggy brain?
> >
> > Thanks,
> > Jim
> >
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