[afnog] BGP Per as route ordering

[Mark Tinka]

On Monday, July 01, 2013 02:02:23 PM Tayeb Meftah wrote:

> Hi people,
> i have a need to block some prefixss
> it's pocible to order the prefixs per as, and then filter
> it using a route map or by any kind, anounce it to my
> Edge and lock them down there? any way to do that?

You don't give much information as to your requirement, but 
typical match conditions could be by BGP Community, prefix 
list and AS_PATH.

The match condition you choose will be determined by the 
scale you're trying to achieve:

	- Prefix lists are explicit and simple, but they
	  scale poorly if you have lots to match.

	- AS_PATH is very flexible, but can be spoofed and
	  may need a prefix list and/or "maximum-prefix"
	  combination to control the (number of) routes
	  being matched.

	- BGP Community is a very powerful match condition,
	  and together with one of the above, provides the
	  most amount of scale. However, it means defining
	  the communities somewhere in your network, so that
	  they can be matched elsewhere.

If we knew more about your situation, we can help more.

Mark.
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