From: Edward Monk (emonk@xxxxxxx)
Date: Mon Mar 25 2002 - 01:00:25 GMT-3
This is what I have gleaned and verified from the BGP Transit area
thread so far.
Route-maps: If you want to add other commands to your route-map. You
must integrate them into the logic of the route-map statement. Pretty
much like any complicated filtering scenario with access-lists. Implicit
deny is in effect just like with access-lists. You can only have one
outgoing route-map to a single neighbor and one incoming from the same
neighbor on each router.
Stuff not in the thread but should be remembered when working with BGP.
Pre-fix lists and distribute-lists are mutually exclusive. That means
you can only use one or the other incoming/outgoing in any combination
just not at the same time incoming or outgoing. That means no
distribute-list in and prefix-list in or out at the same time. If you
use an early IOS like 11.2 or before I think distribute-list in does not
work with IP access-lists.
Now back to the transit area stuff. Anyone think of another way to do
this?
Someone else posted this list I just put solutions up to the list below.
1) easy one using an aspath with the permit ^$, deny all (route-map way)
2) setting the no-export community incoming from each neighbor
3) distribute-list on the neighbor statement
4) filter-list on the neighbor statement
5) tagging the routes incoming from each neighbor and denying that tag
out.
1)
router bgp 200
neighbor x.x.x.x route-map local-only out
route-map local-only 10 permit
match as-path 1
ip as-path access-list 1 permit ^$
2)
router bgp 200
neighbor x.x.x.x route-map comm&metric in
route-map comm&metric permit 10
set community no-export
3)
router bgp 200
neighbor x.x.x.x distribute-list 1 out
access-list 1 permit x.x.x.x x.x.x.x (your networks)
4)
router bgp 200
neighbor x.x.x.x filter-list 1 out
ip as-path access-list 1 permit ^$
5)
router bgp 200
neighbor x.x.x.x route-map set-tag5 in
neighbor x.x.x.x route-map no-tag5 out
route-map set-tag5 permit 10
set tag 5
route-map no-tag5 permit 10
match tag 5
match ip address 1
route-map no-tag5 permit 20
match ip address 2
access-list 1 deny any
access-list 2 permit any
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