Prerequisites: CCNP level skills.
Note!
Topology from Lab 118.
Topology
Task 1
Configure R3 so that it advertises the default route only to R1. This default route should be advertised only if the interface between R3 and R5 is up.
Solution
Task 1
Configure R3 so that it advertises the default route only to R1. This default route should be advertised only if the interface between R3 and R5 is up.
Pic. 2 - R3 Has no Default Route Before Applying Configuration.
!
ip prefix-list R3_R5_LINK seq 5 permit 10.1.35.0/24
!
route-map DEFAULT_ROUTE permit 10
match ip address prefix-list R3_R5_LINK
!
router bgp 30
no synchronization
bgp router-id 172.16.103.3
bgp log-neighbor-changes
network 172.16.103.0 mask 255.255.255.0
neighbor 10.1.13.1 remote-as 10
neighbor 10.1.13.1 default-originate route-map DEFAULT_ROUTE
neighbor 10.1.23.2 remote-as 20
neighbor 10.1.35.5 remote-as 50
no auto-summary
match ip address prefix-list R3_R5_LINK
!
router bgp 30
no synchronization
bgp router-id 172.16.103.3
bgp log-neighbor-changes
network 172.16.103.0 mask 255.255.255.0
neighbor 10.1.13.1 remote-as 10
neighbor 10.1.13.1 default-originate route-map DEFAULT_ROUTE
neighbor 10.1.23.2 remote-as 20
neighbor 10.1.35.5 remote-as 50
no auto-summary
!
Verification:
Pic. 3 - R1's BGP Table.
Pic. 4 - R2's BGP Table.
Only R1 receives the default route.
Now, shutting down the E0/0 on R3.
Pic. 5 - Link between R3 and R5 is Down.
Pic. 6 - R1 Loses the Default Route.
