Hi Experts,

I am simulating a tunnel recursive routing problem using 3 routers. I am using OSPF

(area 0)--R0--(area 1)--R1--(area 1)--R2--(area 2)

R0 Loopback: 1.1.1.1 /32 (advertised in Area 0)

R2 Loopback: 3.3.3.3 /32 (advertised in Area 1)

When GRE tunnel is created using Tunnel source as corresponding Loopback IP address, Tunnel recursive route error start prompting & Tunnel goes down / flapping. I know this is a usual behaviour.

So, I have 3 method to handle this

1. Using static route for Loopback with gateway of serial interface

2. Increase the admin distance to 130 (just an example) for Loopback prefix alone in OSPF process

3. Distribution-list using prefix-list in R0 & R1

I chosed and trying 3rd method (Distribution-list). But it is not working. My example is below

R0:

ip prefix-list LB-3 deny 3.3.3.3/32

ip prefix-list LB-3 permit 0.0.0.0/0 le 32

distribution-list perfix-list LB-3 in tunnel 1

interface tunnel 1

ip add 10.10.10.1 255.255.255.0

tunn source 1.1.1.1

tunn destination 3.3.3.3

R2:

ip prefix-list LB-1 deny 1.1.1.1/32

ip prefix-list LB-1 permit 0.0.0.0/0 le 32

distribution-list perfix-list LB-1 in tunnel 1

interface tunnel 1

ip add 10.10.10.2 255.255.255.0

tunn source 3.3.3.3

tunn destination 1.1.1.1

I thought that in R2 prefix 1.1.1.1 will not be installed thru Tunnel interface. But it is not working.

Please help me to finding out what mistake I am doing. I have tried various option. No clues.

sairam