Prerequisites: CCNP level skills.
Topology
Task 1
Configure full mesh BGP peering according to the topology diagram (pic. 1). Make sure that all BGP sessions in AS 100 can survive a single link loss. If IGP protocol must used, OSPF should be configured. Advertise Loopbacks into BGP.
Task 2
Configure R3 in such a way so the response time of BGP to adjacency changes is improved. Use a method of detecting the loss of the peer that is not based on the interface state but is event driven such as a loss of the path to the IGP address used for peering.
Solution
Task 1
Configure full mesh BGP peering according to the topology diagram (pic. 1). Make sure that all BGP sessions in AS 100 can survive a single link loss. If IGP protocol must be used, OSPF should be configured. Advertise Loopbacks into BGP.
R1 Configuration:
!
router ospf 1
router-id 172.16.101.1
log-adjacency-changes
network 10.1.13.1 0.0.0.0 area 0
network 10.1.14.1 0.0.0.0 area 0
network 172.16.101.1 0.0.0.0 area 0
router-id 172.16.101.1
log-adjacency-changes
network 10.1.13.1 0.0.0.0 area 0
network 10.1.14.1 0.0.0.0 area 0
network 172.16.101.1 0.0.0.0 area 0
!
router bgp 100
no synchronization
bgp router-id 172.16.101.1
bgp log-neighbor-changes
no synchronization
bgp router-id 172.16.101.1
bgp log-neighbor-changes
network 172.16.101.0 mask 255.255.255.0
neighbor 172.16.102.2 remote-as 100
neighbor 172.16.102.2 update-source Loopback0
neighbor 172.16.103.3 remote-as 100
neighbor 172.16.103.3 update-source Loopback0
neighbor 172.16.104.4 remote-as 100
neighbor 172.16.104.4 update-source Loopback0
no auto-summary
neighbor 172.16.102.2 remote-as 100
neighbor 172.16.102.2 update-source Loopback0
neighbor 172.16.103.3 remote-as 100
neighbor 172.16.103.3 update-source Loopback0
neighbor 172.16.104.4 remote-as 100
neighbor 172.16.104.4 update-source Loopback0
no auto-summary
!
R2 Configuration:
!
router ospf 1
router-id 172.16.102.2
log-adjacency-changes
network 10.1.23.2 0.0.0.0 area 0
network 10.1.24.2 0.0.0.0 area 0
network 172.16.102.2 0.0.0.0 area 0
router-id 172.16.102.2
log-adjacency-changes
network 10.1.23.2 0.0.0.0 area 0
network 10.1.24.2 0.0.0.0 area 0
network 172.16.102.2 0.0.0.0 area 0
!
router bgp 100
no synchronization
bgp router-id 172.16.102.2
bgp log-neighbor-changes
no synchronization
bgp router-id 172.16.102.2
bgp log-neighbor-changes
network 172.16.102.0 mask 255.255.255.0
neighbor 172.16.101.1 remote-as 100
neighbor 172.16.101.1 update-source Loopback0
neighbor 172.16.103.3 remote-as 100
neighbor 172.16.103.3 update-source Loopback0
neighbor 172.16.104.4 remote-as 100
neighbor 172.16.104.4 update-source Loopback0
no auto-summary
neighbor 172.16.101.1 remote-as 100
neighbor 172.16.101.1 update-source Loopback0
neighbor 172.16.103.3 remote-as 100
neighbor 172.16.103.3 update-source Loopback0
neighbor 172.16.104.4 remote-as 100
neighbor 172.16.104.4 update-source Loopback0
no auto-summary
!
R3 Configuration:
!
router ospf 1
router-id 172.16.103.3
log-adjacency-changes
network 10.1.13.3 0.0.0.0 area 0
network 10.1.23.3 0.0.0.0 area 0
network 172.16.103.3 0.0.0.0 area 0
router-id 172.16.103.3
log-adjacency-changes
network 10.1.13.3 0.0.0.0 area 0
network 10.1.23.3 0.0.0.0 area 0
network 172.16.103.3 0.0.0.0 area 0
!
router bgp 100
no synchronization
bgp router-id 172.16.103.3
bgp log-neighbor-changes
no synchronization
bgp router-id 172.16.103.3
bgp log-neighbor-changes
network 172.16.103.0 mask 255.255.255.0
neighbor 10.1.35.5 remote-as 50
neighbor 172.16.101.1 remote-as 100
neighbor 172.16.101.1 update-source Loopback0
neighbor 172.16.102.2 remote-as 100
neighbor 172.16.102.2 update-source Loopback0
neighbor 172.16.104.4 remote-as 100
neighbor 172.16.104.4 update-source Loopback0
no auto-summary
neighbor 10.1.35.5 remote-as 50
neighbor 172.16.101.1 remote-as 100
neighbor 172.16.101.1 update-source Loopback0
neighbor 172.16.102.2 remote-as 100
neighbor 172.16.102.2 update-source Loopback0
neighbor 172.16.104.4 remote-as 100
neighbor 172.16.104.4 update-source Loopback0
no auto-summary
!
R4 Configuration:
!
router ospf 1
router-id 172.16.104.4
log-adjacency-changes
network 10.1.14.4 0.0.0.0 area 0
network 10.1.24.4 0.0.0.0 area 0
network 172.16.104.4 0.0.0.0 area 0
router-id 172.16.104.4
log-adjacency-changes
network 10.1.14.4 0.0.0.0 area 0
network 10.1.24.4 0.0.0.0 area 0
network 172.16.104.4 0.0.0.0 area 0
!
router bgp 100
no synchronization
bgp router-id 172.16.104.4
bgp log-neighbor-changes
no synchronization
bgp router-id 172.16.104.4
bgp log-neighbor-changes
network 172.16.104.0 mask 255.255.255.0
neighbor 172.16.101.1 remote-as 100
neighbor 172.16.101.1 update-source Loopback0
neighbor 172.16.102.2 remote-as 100
neighbor 172.16.102.2 update-source Loopback0
neighbor 172.16.103.3 remote-as 100
neighbor 172.16.103.3 update-source Loopback0
neighbor 172.16.101.1 remote-as 100
neighbor 172.16.101.1 update-source Loopback0
neighbor 172.16.102.2 remote-as 100
neighbor 172.16.102.2 update-source Loopback0
neighbor 172.16.103.3 remote-as 100
neighbor 172.16.103.3 update-source Loopback0
!
Verification:
Pic. 2 - R1's BGP Neighbors.
Pic. 3 - R2's BGP Neighbors.
Pic. 4 - R3's BGP Neighbors.
Pic. 5 - R4's BGP Neighbors.
Configure R3 in such a way so the response time of BGP to adjacency changes is improved. Use a method of detecting the loss of the peer that is not based on the interface state but is event driven such as a loss of the path to the IGP address used for peering.
R3 Configuration:
!
router bgp 100
no synchronization
bgp router-id 172.16.103.3
bgp log-neighbor-changes
network 172.16.103.0 mask 255.255.255.0
neighbor 10.1.35.5 remote-as 50
neighbor 172.16.101.1 remote-as 100
neighbor 172.16.101.1 update-source Loopback0
neighbor 172.16.101.1 fall-over
neighbor 172.16.102.2 remote-as 100
neighbor 172.16.102.2 update-source Loopback0
neighbor 172.16.102.2 fall-over
neighbor 172.16.104.4 remote-as 100
neighbor 172.16.104.4 update-source Loopback0
neighbor 172.16.104.4 fall-over
no auto-summary
no synchronization
bgp router-id 172.16.103.3
bgp log-neighbor-changes
network 172.16.103.0 mask 255.255.255.0
neighbor 10.1.35.5 remote-as 50
neighbor 172.16.101.1 remote-as 100
neighbor 172.16.101.1 update-source Loopback0
neighbor 172.16.101.1 fall-over
neighbor 172.16.102.2 remote-as 100
neighbor 172.16.102.2 update-source Loopback0
neighbor 172.16.102.2 fall-over
neighbor 172.16.104.4 remote-as 100
neighbor 172.16.104.4 update-source Loopback0
neighbor 172.16.104.4 fall-over
no auto-summary
!
Verification:
Pic. 6 - BGP Fallover.
Source:
http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/cs_bsfda.html
