From: John Neiberger (neiby@xxxxxxxxxx)
Date: Thu Mar 07 2002 - 16:52:25 GMT-3
Comments inline...
---- On Thu, 7 Mar 2002, Gregg Malcolm (greggm@sbcglobal.net)
wrote:
> I'm pretty sure this has probably been discussed before, but
I've never
> seen
> an explanation. I'm stumped by the following :
>
> The first example uses 2 seq # 's to control routing updates
outside a
> confed
>
> #1
> route-map local_only permit 10
> match ip address 1
> !
> route-map local_only permit 20
> set community no-export
>
In this example, the first entry will allow all prefixes that
match access-list one to pass unaltered. The second entry will
allow _all_ other prefixes and set their community to no-
export. If you only wanted to allow prefixes that match access
list 1 and set the no-export community on those prefixes, you'd
have to put both the match and set statements in the same
sequence.
> The second example has all the criteria in one seq # (except
for the
> permit 20
> with nothing which I also don't understand) to add AS-PATH's
to updates
>
> #2
> route-map prepend permit 10
> match ip address 1
> set as-path prepend 300 400 500
> !
> route-map prepend permit 20
>
In this case, the first statement matches prefixes that match
access list 1 and then prepends those AS numbers. The second
blank permit statement allows all other prefixes to pass
through unchanged. Without this, only prefixes that match
access-list 1 would be advertised.
That's how I understand route map logic, but I'm not sure if
that answers your questions or solves the problem you were
having.
Regards,
John
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