BGP Lab 11 Setting BGP weight (CCNP Level)

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Download Lab: GNS3

Image requirements:
 Cisco IOSv        (vios-adventerprisek9-m.vmdk.SPA.156-2.T)


Introduction:
BGP uses multiple attributes to select routes it will then installed best of them into the BGP table, in this lab, you will modify cisco's proprietary attribute weight, which is locally significant meaning affects only local router and does not get advertised to downstream peers within an autonomous system. BGP weight is the outbound route selection mechanism, it influences how your local router will send traffic to upstream neighbors. All configuration will be performed on the routers ER1 and ER2.


Lab tasks:

1. Configure router ER1 to assign a weight to all routes coming from ISP1 to 1000 and to all routes coming from ISP2 is 2000, use per neighbor weight configuration.

2. Configure router ER2 to choose as the best path to reach AS101 prefix via AS102, the rest of prefixes should not be affected, use weight configuration with a route-map and prefix-list.


Configuration example:

Setting weight using the neighbor weight command:
!
ER1(config)# router bgp 25
ER1(config-router)# neighbor 5.5.5.5 weight 60
!
ER1# clear ip bgp 5.5.5.5 soft
ER1# show ip bgp 50.0.0.0/8 longer-prefixes

Setting weight using the route-map:
!
ER2(config)# ip prefix-list WEIGHT_ROUTE permit 50.0.0.0/20
!
ER2(config)# route-map SET_WEIGHT permit 10
ER2(config-route-map)# match ip address prefix-list WEIGHT_ROUTE
ER2(config-route-map)# set weight 500
ER2(config-route-map)# exit
!
ER2(config)# router bgp 50
ER2(config-router)# neighbor 5.5.5.5 route-map SET_WEIGHT in
ER2(config-router)# end


Topology: