From: Ben (bmunyao@gmail.com)
Date: Fri Jul 20 2007 - 19:18:57 ART
Hi
This is a scenario I encountered in an IE lab. IGP is OSPF and the
requirement is to have R1 get the 10.10.4.0/24 subnet from only one source.
10.10.1.0/24
/-------------R2----|
/ |
R1------/ |10.10.4.0/24
s0/0 \ |
\ |
\--------------R3---|
R1 gets the route 10.10.4.0/24 from R2 and R3 thro OSPF
O 10.10.4.0 [110/65] via 10.10.1.2 .......
[110/65] via 10.10.1.3 ........
In order to filter out the advert from R3 and use only R2 for forwarding,
one can use an extended ACL as follows:
Solution 1
access-l 100 deny host 10.10.1.3 host 10.10.4.0
router ospf 1
distribute-list 100 in s0/0
I tried using a route-map to do the same without much success. Here is what
i did:
Solution 2
ip pref vl4 permit 10.10.4.0/24
ip pref R3 permit 10.10.1.3/32
route-m FILTER deny 10
match ip add pref vl4
match ip next-hop pref R3
route-m FILTER permit 20
router ospf 1
distribute-list route-m FILTER in
Solution 3
p pref vl4 permit 10.10.4.0/24
ip pref R3 permit 10.10.1.3/32
route-m FILTER deny 10
match ip add pref vl4
match ip route-source pref R3
route-m FILTER permit 20
router ospf 1
distribute-list route-m FILTER in
Neither solution 2 nor solution 3 worked for me. Logically they appear
sound. i would appreciate any comments on these approaches.
TIA
Ben
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