From: Michael C. Popovich (mpopovich@xxxxxxxxxx)
Date: Thu Mar 07 2002 - 19:37:26 GMT-3
The way I read what your two options provide is as follows:
#1
Permit 10 matches access-list 1 but isn't given any instructions on what
to do so the networks matching list one are permitted without change,
networks not matching list 1 are sent to seq. 20 and there all networks
match and then set with community no-export.
#2
Match ip address 1 then prepend as-path with 200 400 500. Any packets
not matching list 1 then go to seq. #20 which allows everything through.
Route-maps work like access-lists in that if there is no match then
there is an implicit deny at the end. So if you want packets/networks
that don't match a route-map sequence to be passed and not dropped then
you need to add a blank sequence at the end.
I question if the #1 example is really working the way you want. It's my
understanding that they way it is written networks that match
access-list 1 would not pass to the next sequence number and therefore
would not have their community set for no-export.
-----Original Message-----
From: Gregg Malcolm [mailto:greggm@sbcglobal.net]
Sent: Thursday, March 07, 2002 1:28 PM
To: ccielab@groupstudy.com
Subject: Route Map Logic
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
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
I've tried both of these with all statements in 1 sequence number and
with 2
sequence numbers with 1 statement each. Both will only work as done in
these
two examples. Does anyone have a explanation ? Why can't both be done
with a
single sequence number ? If there any easy way to remember when to use
1 seq
and when to use 2 seq's ?
TIA, Gregg
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