Re: Problems with route filtering for OSPF with

From: Malcolm Salmons (malcolm.salmons@gmail.com)
Date: Mon Jun 18 2007 - 15:52:05 ART


Hi

I've worked out why this wouldnt work so dont worry about it. I was
filtering the forwarding address for the E2 route out.

R5#sh ip ospf database external

            OSPF Router with ID (136.10.5.5) (Process ID 1)

                Type-5 AS External Link States

  LS age: 1978
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 192.168.90.0 (External Network Number )
  Advertising Router: 136.10.6.6
  LS Seq Number: 80000005
  Checksum: 0xA46
  Length: 36
  Network Mask: /24
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 20
        Forward Address: *136.10.9.9
* External Route Tag: 69

R5#

Thanks

Malcolm
On 6/18/07, Malcolm Salmons <malcolm.salmons@gmail.com> wrote:
>
> Hi
>
> I'm trying to filter certain OSPF routes from my routing table using
> distribute lists. However, I'm getting problems with allowing external
> routes through. I can filter internal routes with access list and a route
> map but I cant get external routes permitted. I've hacked around with
> different route-map matches, including route-type, tag etc but cant seem to
> get it to do what I want.
>
> With a distribute list applied I have the following routes:
>
> R5#sir ospf
> 136.10.0.0/16 is variably subnetted, 9 subnets, 5 masks
> O IA 136.10.9.9/32 [110/3] via 136.10.56.6 , 00:00:07, FastEthernet0/0
> O IA 136.10.7.7/32 [110/2] via 136.10.56.7, 00:00:07, FastEthernet0/0
> O IA 136.10.6.6/32 [110/2] via 136.10.56.6, 00:00:07, FastEthernet0/0
> O IA 136.10.69.0/24 [110/2] via 136.10.56.6, 00:00:07, FastEthernet0/0
> O E2 192.168.90.0/24 [110/20] via 136.10.56.6, 00:00:07, FastEthernet0/0
> R5#
>
> I'm trying to only allow 136.10.69.0/24 and 192.168.90.0/24. I've allowed
> both in an acl and applied it with a route-map. This didnt seem to pick up
> the E2 route, so I tagged this and matched on that, again without success.
> My config is as follows:
>
>
> router ospf 1
> router-id 136.10.5.5
> log-adjacency-changes
> network 136.10.5.5 0.0.0.0 area 5
> network 136.10.55.55 0.0.0.0 area 55
> network 136.10.56.5 0.0.0.0 area 0
> distribute-list route-map FILTER2 in
>
> access-list 99 permit 136.10.69.0 0.0.0.255
> access-list 99 permit 192.168.90.0 0.0.0.255
>
> route-map FILTER2 permit 10
> match ip address 99
> !
> route-map FILTER2 permit 20
> match tag 69
> !
>
> I can see that the E2 route is tagged with 69:
>
> R5#sh ip ospf data
>
> OSPF Router with ID (136.10.5.5) (Process ID 1)
>
> - Lines removed
> Type-5 AS External Link States
>
> Link ID ADV Router Age Seq# Checksum Tag
> 192.168.90.0 136.10.6.6 497 0x80000004 0x000C45 69
> R5#
>
> But all I get in the routing table is the internal /24:
>
> R5#sir ospf
> 136.10.0.0/16 is variably subnetted, 6 subnets, 4 masks
> O IA 136.10.69.0/24 [110/2] via 136.10.56.6 , 00:04:25, FastEthernet0/0
> R5#
>
>
>
> Any help on this is appreciated.
>
> Thanks
>
> Malcolm



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