Lab 28 - OSPF Stub Router Advertisement - Learn Cisco

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Lab 28 - OSPF Stub Router Advertisement

Prerequisites: CCNP level skills.

Note!
Use the configuration from Lab6.

Topology

Pic. 1 - OSPF Topology.
Icons designed by: Andrzej Szoblik - http://www.newo.pl

Task 1
On R4 check the OSPF routing table. Also, check what cost R2 advertises towards 172.16.103.0/24 and 172.16.133.0/24.

Task 2
Configure routers so R2 advertises maximum metric for all prefixes except the ones that area originated by R2. Use one command to accomplish that.

Lab Solution

Task 1
On R4 check the OSPF routing table. Also, check what cost R2 advertises towards 172.16.103.0/24 and 172.16.133.0/24.

Pic. 2 - R4's Routing Table.

Pic. 3 - 172.16.103.0/24 LSA Advertised by R2.
Task 2
Configure routers so R2 advertises maximum metric for all prefixes except the ones that area originated by R2. Use one command to accomplish that.

R2 OSPF Configuration:
!
router ospf 1
 router-id 2.2.2.2
 max-metric router-lsa
 log-adjacency-changes
 network 10.1.23.2 0.0.0.0 area 0
 network 10.1.124.2 0.0.0.0 area 1
 network 172.16.102.2 0.0.0.0 area 0
!

Verification:
Pic. 4 - R4's Routing Table.
Notice!
R2's Loopback0 (originated by R2) is advertised with its original metric (1; Metric=2 because of the cost of R4 to reach R2).

Pic. 5 - R2's LSA (172.16.102.0/24) with Original Cost.

Pic. 6 - 172.16.103.0/24 LSA Advertised by R2.
Note!
All LSAs (except for the originated one) R2 advertises with the maximu metric value 65536.

Note!
The 'max-metric router-lsa' command takes a few options. Without options (like in this post), R2 advertises max metric infinitely. If this cost should be advertised in a given time only (maintenance or other) the following options are available:

Pic. 7 - Options on-start.

Pic. 8 - Other Options.

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