RE: Rip Filter Problem

From: Jonathan Hays (nomad@gfoyle.org)
Date: Mon Mar 15 2004 - 12:18:45 GMT-3


>R 204.12.4.0/24 [120/1] via 204.12.1.254, 00:00:08, Vlan204
>R 204.12.6.0/24 [120/1] via 204.12.1.254, 00:00:08, Vlan204
[snip]
>distance 255 204.12.0.0 0.0.255.255 44

Is it possible that the originating router does not have an IP address
in the 204.12.0.0 address space? The ip address referenced in the
distance command is that of the originating router, not the next hop.
The 'via 204.12.1.254' in your routing table refers to the next hop, not
the originating router. Enter 'sh ip route 204.12.4.0' to get more info.

See this excellent explanation from Brian McGahan for more detail.

http://www.groupstudy.com/archives/ccielab/200307/msg01607.html

>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
>Behalf Of Keith Thuerk
>Sent: Monday, March 15, 2004 9:52 AM
>To: ccielab@groupstudy.com
>Subject: Rip Filter Problem
>
>
>Attempting to filter to meet the requirements in INE Lab book
>"Cfg SW1 so that it doesn't accept routers w/ an even 2nd
>octect from BB3. The ACL should not contain > 1 line. Don't
>use a dist-list!
>
>My approach was to use distance to perform the filtering however,
>I was never able to get the filter to work properly.
>The ACL I created was valid when using just the dist-list
>(don't panic it was only for testing purposes), when combined
>w/ the distance cmd it oddly permited two even routes.
>
>SW1#sir
>Codes: C - connected, S - static, I - IGRP, R - RIP, M -
>mobile, B - BGP
>D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
>N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
>E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
>i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS
>inter area
>* - candidate default, U - per-user static route, o - ODR
>P - periodic downloaded static route
>
>Gateway of last resort is not set
>
>C 204.12.1.0/24 is directly connected, Vlan204
>C 204.12.2.0/24 is directly connected, Vlan783
>R 204.12.4.0/24 [120/1] via 204.12.1.254, 00:00:08, Vlan204
>54.0.0.0/24 is subnetted, 1 subnets
>O E1 54.1.1.0 [110/224] via 132.2.17.1, 00:55:31, FastEthernet0/1
>R 204.12.6.0/24 [120/1] via 204.12.1.254, 00:00:08, Vlan204
>132.2.0.0/16 is variably subnetted, 13 subnets, 3 masks
>C 132.2.6.0/24 is directly connected, Vlan6
>O IA 132.2.0.4/32 [110/74] via 132.2.17.1, 00:55:31, FastEthernet0/1
>O IA 132.2.0.2/32 [110/74] via 132.2.17.1, 00:55:31, FastEthernet0/1
>O IA 132.2.3.0/24 [110/84] via 132.2.17.1, 00:46:11, FastEthernet0/1
>O IA 132.2.0.3/32 [110/74] via 132.2.17.1, 00:46:11, FastEthernet0/1
>O IA 132.2.0.1/32 [110/10] via 132.2.17.1, 00:55:31, FastEthernet0/1
>
>SW1#sir rip
>R 204.12.4.0/24 [120/1] via 204.12.1.254, 00:00:19, Vlan204
>R 204.12.6.0/24 [120/1] via 204.12.1.254, 00:00:19, Vlan204
>
>
>SW1#sho ip access-
>Standard IP access list 44
>permit 204.12.1.0, wildcard bits 0.0.254.255 (10391 matches)
>check=10421
>SW1#f router rip
>router rip
>version 2
>no validate-update-source
>redistribute ospf 1 metric 10
>passive-interface default
>no passive-interface Vlan204
>network 204.12.1.0
>neighbor 204.12.1.254
>distance 255 204.12.0.0 0.0.255.255 44
>no auto-summary
>
>My results did not vary even though I changed the way the
>distance cmd was structured. i.e when I changed the mask definition.
>
>
>Question 1: Is there a better way to filter w/ in RIP (keeping
>in mind the restriction NOT to use a dist-list?
>
>
>Question 2: What am I doing wrong in above sol'n?
>
>Keith
>
>
>
>
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