Network Diagram:
*****************************************************************
AIM: See how to add communities to updates
*****************************************************************
================================================
R2 Configuration:
=================================================
router bgp 1
no synchronization
bgp router-id 2.2.2.2
bgp default local-preference 500
network 2.2.2.2 mask 255.255.255.255
network 10.1.1.0 mask 255.255.255.0
network 10.1.2.0 mask 255.255.255.0
network 10.1.3.0 mask 255.255.255.0
neighbor 1.1.1.1 remote-as 1
neighbor 1.1.1.1 ebgp-multihop 255
neighbor 1.1.1.1 update-source Loopback0
neighbor 1.1.1.1 route-reflector-client
neighbor 1.1.1.1 prefix-list david in
neighbor 3.3.3.3 remote-as 1
neighbor 3.3.3.3 ebgp-multihop 255
neighbor 3.3.3.3 update-source Loopback0
neighbor 3.3.3.3 route-reflector-client
neighbor 3.3.3.3 send-community <= Send community to neighbor
neighbor 3.3.3.3 route-map setcommunity out <= Specify community with a
route-map
neighbor 4.4.4.4 remote-as 2
neighbor 4.4.4.4 ebgp-multihop 255
neighbor 4.4.4.4 update-source Loopback0
neighbor 4.4.4.4 send-community
neighbor 4.4.4.4 route-map setcommunity out
no auto-summary
!
ip classless
ip route 1.1.1.1 255.255.255.255 10.1.1.1
ip route 3.3.3.3 255.255.255.255 10.1.3.2
ip route 4.4.4.4 255.255.255.255 10.1.2.2
no ip http server
ip bgp-community new-format
!
!
ip prefix-list david seq 5 deny 7.7.7.7/32
ip prefix-list david seq 10 permit 0.0.0.0/0 le 32
access-list 1 permit any <======= Community applies
to all routes
route-map setmetricout permit 10
set metric 100
!
route-map setcommunity permit 10 <======= Specify community with a
route-map
match ip address 1
set community 1:1
================================================
R4 Configuration:
=================================================
!
router bgp 2
no synchronization
bgp router-id 4.4.4.4
network 4.4.4.4 mask 255.255.255.255
network 10.1.2.0 mask 255.255.255.0
network 10.1.5.0 mask 255.255.255.0
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 ebgp-multihop 255
neighbor 2.2.2.2 update-source Loopback0
neighbor 5.5.5.5 remote-as 2
neighbor 5.5.5.5 ebgp-multihop 255
neighbor 5.5.5.5 update-source Loopback0
neighbor 5.5.5.5 next-hop-self
neighbor 5.5.5.5 send-community <= Send community to neighbor
Do this on all the other routers
neighbor 5.5.5.5 route-map setnexthop in
no auto-summary
!
no ip http server
ip classless
ip route 2.2.2.2 255.255.255.255 10.1.2.1
ip route 5.5.5.5 255.255.255.255 10.1.5.2
!
route-map setnexthop permit 10
set ip next-hop peer-address
!
================================================
R4 Output:
================================================
================================================
R4 Config changes
================================================
r4(config)#ip bgp new-format
================================================
R4 Output:
================================================
================================================
R6 Output:
================================================
*****************************************************************
AIM: Change the community on R4 - you will see it overrides other community
*****************************************************************
================================================
R4 Config Changes:
================================================
router bgp 2
no synchronization
bgp router-id 4.4.4.4
network 4.4.4.4 mask 255.255.255.255
network 10.1.2.0 mask 255.255.255.0
network 10.1.5.0 mask 255.255.255.0
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 ebgp-multihop 255
neighbor 2.2.2.2 update-source Loopback0
neighbor 5.5.5.5 remote-as 2
neighbor 5.5.5.5 ebgp-multihop 255
neighbor 5.5.5.5 update-source Loopback0
neighbor 5.5.5.5 next-hop-self
neighbor 5.5.5.5 send-community
neighbor 5.5.5.5 route-map setnexthop in
neighbor 5.5.5.5 route-map sendcommunity out
no auto-summary
!
no ip http server
ip classless
ip route 2.2.2.2 255.255.255.255 10.1.2.1
ip route 5.5.5.5 255.255.255.255 10.1.5.2
ip bgp-community new-format
!
access-list 2 permit any
route-map setnexthop permit 10
set ip next-hop peer-address
!
route-map sendcommunity permit 10 <===== Change community to 2:2
match ip address 2
set community 2:2
!
================================================
R5 Output:
================================================
*****************************************************************
AIM: Change the community on R4 - don't override other community
*****************************************************************
================================================
R4 Config Changes:
================================================
router bgp 2
no synchronization
bgp router-id 4.4.4.4
network 4.4.4.4 mask 255.255.255.255
network 10.1.2.0 mask 255.255.255.0
network 10.1.5.0 mask 255.255.255.0
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 ebgp-multihop 255
neighbor 2.2.2.2 update-source Loopback0
neighbor 5.5.5.5 remote-as 2
neighbor 5.5.5.5 ebgp-multihop 255
neighbor 5.5.5.5 update-source Loopback0
neighbor 5.5.5.5 next-hop-self
neighbor 5.5.5.5 send-community
neighbor 5.5.5.5 route-map setnexthop in
neighbor 5.5.5.5 route-map sendcommunity out
no auto-summary
!
no ip http server
ip classless
ip route 2.2.2.2 255.255.255.255 10.1.2.1
ip route 5.5.5.5 255.255.255.255 10.1.5.2
ip bgp-community new-format
!
access-list 2 permit any
route-map setnexthop permit 10
set ip next-hop peer-address
!
route-map sendcommunity permit 10 <===== Add to community list use -
ADDITIVE - doesn't override community
match ip address 2
set community 2:2 additive
!
================================================
R5 Output:
================================================
================================================
R6 Output:
================================================
*****************************************************************
AIM: Lets set weights based on the community
*****************************************************************
================================================
R6 Config changes:
================================================
router bgp 3
no synchronization
bgp router-id 6.6.6.6
network 6.6.6.6 mask 255.255.255.255
network 10.1.6.0 mask 255.255.255.0
neighbor 5.5.5.5 remote-as 2
neighbor 5.5.5.5 ebgp-multihop 255
neighbor 5.5.5.5 update-source Loopback0
neighbor 5.5.5.5 route-map checkcommunity in <===== Check communities
coming in
no auto-summary
!
ip classless
ip route 5.5.5.5 255.255.255.255 10.1.6.1
no ip http server
ip bgp-community new-format <===== Display in new format
ip community-list 5 permit 1:1 <===== For communtiy 1:1
ip community-list 6 permit internet <===== For everything else
!
access-list 1 permit any
route-map setnexthop permit 10
match ip address 1
set ip next-hop peer-address
!
route-map setnexthop permit 20
!
route-map checkcommunity permit 10 <===== Check communities coming in
match community 5
set weight 20
!
route-map checkcommunity permit 20 <===== Check communities coming in
match community 6
set weight 1
================================================
R6 Output:
================================================
Notice above - routers with AS 1 in the AS path have weight set to 20, and those with AS path set to 2 only have weight set to 1
I hope that this has been beneficial to you.
To your success,
David Bombal
|
