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AS learn in ospf  the area range should only be configure at the ABR only not at the Backbone are.But in this scenario it is configure at area 0.If we configure at area 3 it will not send any null routes.Plz explain .. why it configure in area 0.

"Area 0 range" is configured on ABR R5 in area 0 as we do summarization of routes coming from area 0 and we want to have them summarized in other areas (area 3 in this situation).

I don't see how did you manage to get this task working.

1. r5/sw2/sw4 have access to r1 lo0, because of the previous tasks (6.35-6.36) when we advertise default route to ospf domain.

2. r5/sw2/sw4 will no have access to r2 lo0 even if you configure summarization to area3. Because r5 will still be using default route to r4 and loop between r4 and r5 will happen.

3. If r5 will be getting a default route from r6 instead of r4, loop will from between r1 and r5.

did you find answer for this?

My problem is the same>

R5:

router ospf 1

 router-id 150.1.5.5

 log-adjacency-changes

 no discard-route

 area 0 range 150.1.0.0 255.255.252.0

 distribute-list prefix NO-R1-R2 in

ip prefix-list NO-R1-R2 seq 5 deny 150.1.1.1/32

ip prefix-list NO-R1-R2 seq 10 deny 150.1.2.2/32

ip prefix-list NO-R1-R2 seq 15 permit 0.0.0.0/0 le 32

Rack1R5(config)#do sir 150.1.1.1  

% Subnet not in table

Rack1R5(config)#do sir 150.1.2.2  

% Subnet not in table

Rack1R5(config)#do sir 0.0.0.0                                

Routing entry for 0.0.0.0/0, supernet

  Known via "ospf 1", distance 110, metric 1, candidate default path

  Tag 1, type extern 2, forward metric 64

  Last update from 155.1.45.4 on Serial1/1, 00:04:44 ago

  Routing Descriptor Blocks:

    155.1.45.4, from 150.1.4.4, 00:04:44 ago, via Serial1/1

      Route metric is 1, traffic share count is 1

      Route tag 1

  * 155.1.0.4, from 150.1.4.4, 00:04:44 ago, via Serial1/0

      Route metric is 1, traffic share count is 1

      Route tag 1

SW4:

Rack1SW4(config)#do tracer 150.1.1.1   

  1 155.1.108.8 0 msec 4 msec 0 msec

  2 155.1.58.5 0 msec 4 msec 0 msec

  3 155.1.0.4 20 msec 20 msec 20 msec

  4 155.1.146.1 32 msec *  28 msec

Rack1SW4(config)#do tracer 150.1.2.2   

  1 155.1.108.8 4 msec 4 msec 4 msec

  2 155.1.58.5 0 msec 0 msec 0 msec

  3 155.1.45.4 20 msec 20 msec 20 msec

  4 155.1.0.5 20 msec 16 msec 16 msec

  5 155.1.45.4 40 msec 36 msec 40 msec

  6 155.1.0.5 32 msec 32 msec 36 msec

  7 155.1.45.4 56 msec 52 msec 52 msec

  8 155.1.0.5 48 msec 48 msec 48 msec

  9 155.1.45.4 68 msec 72 msec 68 msec

I can't reach R2 Lo0.!!!!!!!

I think this question was a mistake and that it's not going to work with the existing setup. Perhaps if the link ethernet link between R1 and R4 was in area 0, R4 would have been able to route the traffic over that link.

Cheers guys.

Moath Rawashdeh

Guys,

In order to make SG solution working for R2 loopback too I just added static route on R5 pointing to R2. This is to fix the route recursion loop between R5 and R4.

# R5

ip route 150.1.2.2 255.255.255.255 155.1.0.2

Tom