Prerequisites: CCNP level skills.
Topology
Pic. 1 – OSPF Topology.
Task 1
On R1 check the paths towards 10.1.23.0/24.
Task 2
Manipulate the OSPF cost so R1 prefers R2 towards 10.1.23.0/24.
Lab Solution
Task 1
On R1 check the paths towards 10.1.23.0/24.
Note!
Changing the cost on Loopback interfaces does not influence the path selection. R2 is the DR (representative) providing access to what is advertised by the originator of the subnets 172.16.102.0/24 and 172.16.103.0/24. There is only ONE originator of these subnets unlike 10.1.23.0/24.
Pic. 2 – R1 Routing Table.
Task 2
Manipulate the OSPF cost so R1 prefers R2 towards 10.1.23.0/24.
Note!
Both R2‘s and R3 ‘s cost towards 10.1.23.0/24 is 1 (auto-cost reference-bandwidth = 100,000,000/bandwidth of the F1/0 interface). R1’s cost of s0/0 = 64.
Pic. 3 – R2’s Cost to 10.1.23.0/24.
Pic. 4 – R3 Cost to 10.1.23.0/24.
R3 Configuration:
!
interface FastEthernet1/0
ip address 10.1.23.3 255.255.255.0
ip ospf cost 2
!
ip address 10.1.23.3 255.255.255.0
ip ospf cost 2
!
Verification:
Pic. 5 – R1’s Routing Table
