Re: BGP suppress maps posted 12/29/2007
- Subject: Re: BGP suppress maps
- From: nhatphuc <nhatphuc@xxxxxxxxx>
- Date: Sat, 29 Dec 2007 15:37:38 +0700
- Cc: "Jim McBurnett" <jim@xxxxxxxxxxxxxxxx>, ccielab@xxxxxxxxxxxxxx
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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)
On Dec 29, 2007 3:26 PM, Joseph Brunner <joe@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of
> Sent: Saturday, December 29, 2007 3:02 AM
> To: Jim McBurnett
> Cc: ccielab@xxxxxxxxxxxxxx
> 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
> On Dec 28, 2007 9:15 AM, Jim McBurnett <jim@xxxxxxxxxxxxxxxx> 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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