Dell PowerConnect B-RX Configuration Manual page 832

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BGP Null0 routing
5. On Router 6, redistribute the static routes into BGP, using route-map <route-map-name>
6. On Router 1, the router facing the internet, configure a null0 route matching the next-hop
7.
8. On Router 6, configure the network prefixes associated with the traffic you want to drop. The
Configuration examples
Router 6
The following configuration defines specific prefixes to filter.
BigIron RX(config)#ip route 110.0.0.40/29 ethernet 3/7 tag 50
BigIron RX(config)#ip route 115.0.0.192/27 ethernet 3/7 tag 50
BigIron RX(config)#ip route 120.014.0/23 ethernet 3/7 tag 50
The following configuration redistributes routes into BGP.
BigIron RX(config)#router bgp
BigIron RX(config-bgp-router)#local-as 100
BigIron RX(config-bgp-router)#neighbor <router1_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router2_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router3_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router4_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router5_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router7_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#redistribute static route-map blockuser
BigIron RX(config-bgp-router)#exit
The following configuration defines the specific next hop address and sets the local preference to
preferred.
BigIron RX(config)#route-map blockuser permit 10
BigIron RX(config-routemap blockuser)#match tag 50
BigIron RX(config-routemap blockuser)#set ip next-hop 199.199.1.1
BigIron RX(config-routemap blockuser)#set local-preference 1000000
BigIron RX(config-routemap blockuser)#set origin igp
BigIron RX(config-routemap blockuser)#exit
Router 1
The following configuration defines the null0 route to the specific next hop address. The next hop
address 199.199.1.1 points to 128.178.1.101, which gets blocked.
BigIron RX(config)# ip route 199.199.1.1/32 null0
BigIron RX(config)#router bgp
local-as 100
BigIron RX(config-bgp-router)#neighbor <router2_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router3_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router4_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router5_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router6_int_ip address> remote-as 100
BigIron RX(config-bgp-router)#neighbor <router7_int_ip address> remote-as 100
756
(redistribute static route-map block user).
address in the route-map (ip route 199.199.1.1/32 null0).
Repeat step 3 for all routers interfacing with the internet (edge corporate routers). In this case,
Router 2 has the same null0 route as Router 1.
static route IP address references a destination address. You are required to point the static
route to the egress port, for example, Ethernet 3/7, and specify the tag 50, matching the
route-map configuration.
BigIron RX Series Configuration Guide
53-1002253-01