Task 1
Configure OSPF area 58 between R5 and SW2 (Vlan 58). Ensure that Vlan 58 does have connectivity to all prefixes in OSPF domain even if connection between R5 and SW2 failed. You can create two new IP addresses to accomplish the goal.
- Can OSPF virtual-link be configured over a transit area that is stub or nssa?
- What is another method of extending area 0 if another area is not physically connected to the backbone area?
Lab Solution
Solution configuration can be accessed below; solution contains task 1 and task 2 (if you want to save it, click the link, then go to File-->Download):
https://drive.google.com/file/d/0BwE5C95tpjZOaGg4WE8yR3RNcWs/edit?usp=sharing
Task 1
Configure OSPF area 58 between R5 and SW2 (Vlan 58). Ensure that Vlan 58 does have connectivity to all prefixes in OSPF domain even if connection between R5 and SW2 failed. You can create two new IP addresses to accomplish the goal.
Note!
As per lab stipulation, area 58 must be also linked through area 28 to the backbone area to provide connectivity in case of R5 to SW2 link failure. However, area 28 is nssa and virtual-link cannot be used to make SW2 an ABR, GRE tunnel must be used instead.
R2 Config:
!
interface tunnel0
ip address 192.168.28.2 255.255.255.0
tunnel source f0/1
tunnel destination 172.16.28.8
!
router ospf 1
network 192.168.28.2 0.0.0.0 area 0
!
SW2 Config:
!
interface tunnel0
ip address 192.168.28.8 255.255.255.0
tunnel source vlan 28
tunnel destination 172.16.28.2
!
router ospf 1
network 192.168.28.8 0.0.0.0 area 0
network 172.16.58.8 0.0.0.0 area 58
!
R5 Config:
!
router ospf 1
log-adjacency-changes
area 45 virtual-link 10.0.4.4
area 59 virtual-link 10.0.9.9
network 172.16.45.5 0.0.0.0 area 45
network 172.16.58.5 0.0.0.0 area 58
network 172.16.59.5 0.0.0.0 area 59
!
Pic. 2 - Status of GRE Tunnel.
Pic. 3 - Vlan 58 Availability.
Shut down interface Fas0/0 on R5. The ping test from R6 is still successful!
OSPF virtual-link cannot cross any transit area that is stub or nssa. An alternative solution is to use GRE tunnel.