50. Community attribute community of BGP configuration experiment
1. Community analysis of community attributes.
BGP Community Properties community:
Can be enabled: BGP community attribute community is optional and is not recognized by default. Can be turned on by command: neighbor x.x.x.x send-community
Transitivity: BGP community attribute community is only valid for neighbors. Neighbors of neighbors are no longer valid. Neighbors who want to pass to neighbors need to configure neighbor x.x.x.x send-community.
To modify the BGP community attributes community:
Ip prefix-list 1 permit 1.1.1.0/24
Route-map COM permit 10
Match ip address prefix-list 1
Set community no-advertise does not pass to BGP neighbors
Set community no-export does not emit large AS.
Set community local-AS does not send out little AS.
Route-map COM permit 20
Router bgp 1
Neighbor 12.1.1.2 send-community
Neighbor 12.1.1.2 route-map COM out
2. Experimental topology
3. Basic configuration
R1 configuration
Interface Loopback0
Ip address 1.1.1.1 255.255.255.0
Interface Serial0/0
Ip address 12.1.1.1 255.255.255.0
Router bgp 1
No synchronization
Bgp router-id 1.1.1.1
Network 1.1.1.0 mask 255.255.255.0
Neighbor 12.1.1.2 remote-as 2
Neighbor 12.1.1.2 send-community
No auto-summary
R2 configuration
Interface Loopback0
Ip address 2.2.2.2 255.255.255.0
Interface Serial0/0
Ip address 12.1.1.2 255.255.255.0
Interface Serial0/1
Ip address 23.1.1.2 255.255.255.0
Router ospf 110
Router-id 2.2.2.2
Network 2.2.2.0 0.0.0.255 area 0
Network 23.1.1.0 0.0.0.255 area 0
Router bgp 64512
No synchronization
Bgp router-id 2.2.2.2
Bgp confederation identifier 2
Neighbor 3.3.3.3 remote-as 64512
Neighbor 3.3.3.3 update-source Loopback0
Neighbor 3.3.3.3 next-hop-self
Neighbor 12.1.1.1 remote-as 1
Neighbor 3.3.3.3 send-community
No auto-summary
R3 configuration
Interface Loopback0
Ip address 3.3.3.3 255.255.255.0
Interface Serial0/0
Ip address 34.1.1.3 255.255.255.0
Interface Serial0/1
Ip address 23.1.1.3 255.255.255.0
Router ospf 110
Router-id 3.3.3.3
Network 3.3.3.0 0.0.0.255 area 0
Network 23.1.1.0 0.0.0.255 area 0
Network 34.1.1.0 0.0.0.255 area 0
Router bgp 64512
No synchronization
Bgp router-id 3.3.3.3
Bgp confederation identifier 2
Bgp confederation peers 64513
Neighbor 2.2.2.2 remote-as 64512
Neighbor 2.2.2.2 update-source Loopback0
Neighbor 4.4.4.4 remote-as 64513
Neighbor 4.4.4.4 ebgp-multihop 255
Neighbor 4.4.4.4 update-source Loopback0
Neighbor 4.4.4.4 send-community
No auto-summary
R4 configuration
Interface Loopback0
Ip address 4.4.4.4 255.255.255.0
Interface Serial0/0
Ip address 34.1.1.4 255.255.255.0
Interface Serial0/1
Ip address 45.1.1.4 255.255.255.0
Router ospf 110
Router-id 4.4.4.4
Network 4.4.4.0 0.0.0.255 area 0
Network 34.1.1.0 0.0.0.255 area 0
Network 45.1.1.0 0.0.0.255 area 0
Router bgp 64513
No synchronization
Bgp router-id 4.4.4.4
Bgp confederation identifier 2
Bgp confederation peers 64512
Neighbor 3.3.3.3 remote-as 64512
Neighbor 3.3.3.3 ebgp-multihop 255
Neighbor 3.3.3.3 update-source Loopback0
Neighbor 5.5.5.5 remote-as 64513
Neighbor 5.5.5.5 update-source Loopback0
Neighbor 5.5.5.5 send-community
No auto-summary
R5 configuration
Interface Loopback0
Ip address 5.5.5.5 255.255.255.0
Interface Serial0/0
Ip address 56.1.1.5 255.255.255.0
Interface Serial0/1
Ip address 45.1.1.5 255.255.255.0
Router ospf 110
Router-id 5.5.5.5
Network 5.5.5.0 0.0.0.255 area 0
Network 45.1.1.0 0.0.0.255 area 0
Router bgp 64513
No synchronization
Bgp router-id 5.5.5.5
Bgp confederation identifier 2
Neighbor 4.4.4.4 remote-as 64513
Neighbor 4.4.4.4 update-source Loopback0
Neighbor 56.1.1.6 remote-as 6
Neighbor 56.1.1.6 send-community
No auto-summary
R6 configuration
Interface Loopback0
Ip address 6.6.6.6 255.255.255.0
Interface Serial0/0
Ip address 56.1.1.6 255.255.255.0
Router bgp 6
No synchronization
Bgp router-id 6.6.6.6
Neighbor 56.1.1.5 remote-as 2
No auto-summary
4. Community attribute verification
Ip prefix-list 1 seq 5 permit 1.1.1.0/24
Route-map COM permit 10
Match ip address prefix-list 1
Set community no-advertise
Route-map COM permit 20
Router bgp 1
Neighbor 12.1.1.2 send-community
Neighbor 12.1.1.2 route-map COM out
Ip prefix-list 1 seq 5 permit 1.1.1.0/24
Route-map COM permit 10
Match ip address prefix-list 1
Set community no-export
Route-map COM permit 20
Router bgp 1
Neighbor 12.1.1.2 send-community
Neighbor 12.1.1.2 route-map COM out
Ip prefix-list 1 seq 5 permit 1.1.1.0/24
Route-map COM permit 10
Match ip address prefix-list 1
Set community local-AS
Route-map COM permit 20
Router bgp 1
Neighbor 12.1.1.2 send-community
Neighbor 12.1.1.2 route-map COM out
