Prerequisites: CCNP level skills.
BGP Default Communities
- internet - Advertise this route to the Internet community. All routers belong to it.
- no-export - Do not advertise this route to eBGP peers (real BGP peers).
- no-advertise - Do not advertise this route to any peer (internal or external).
- local-as - Do not advertise this route to peers outside the local autonomous system. This route will not be advertised to other autonomous systems or sub-autonomous systems when confederations are configured.
http://www.cisco.com/en/US/docs/ios/12_2/ip/configuration/guide/1cfbgp.html#wp1001855
Notice!
AS 13 is a confederation autonomous system. It has two sub-autonomous systems: 65001 and 65003.
Topology
Task 1
R5 is advertising 172.16.105.0/24 into BGP. Use the BGP community so that R3 does not advertise it any further.
Solution
Task 1
R5 is advertising 172.16.105.0/24 into BGP. Use the BGP community so that R3 does not advertise it any further.
R5 Configuration:
!
ip prefix-list LOOPBACK0 seq 5 permit 172.16.105.0/24
ip prefix-list LOOPBACK0 seq 5 permit 172.16.105.0/24
!
route-map SET_COMMUNITY permit 10
match ip address prefix-list LOOPBACK0
set community no-advertise
!
route-map SET_COMMUNITY permit 999
!
router bgp 50
no synchronization
bgp router-id 172.16.105.5
bgp log-neighbor-changes
network 172.16.105.0 mask 255.255.255.0
neighbor 10.1.35.3 remote-as 13
neighbor 10.1.35.3 send-community
neighbor 10.1.35.3 route-map SET_COMMUNITY out
no auto-summary
match ip address prefix-list LOOPBACK0
set community no-advertise
!
route-map SET_COMMUNITY permit 999
!
router bgp 50
no synchronization
bgp router-id 172.16.105.5
bgp log-neighbor-changes
network 172.16.105.0 mask 255.255.255.0
neighbor 10.1.35.3 remote-as 13
neighbor 10.1.35.3 send-community
neighbor 10.1.35.3 route-map SET_COMMUNITY out
no auto-summary
!
Verification:
Pic. 2 - BGP Prefix on R3.
