Configure the switch to reject inbound route advertisements for any Bogon prefixes.
Step 1: Configure a prefix list containing the current Bogon prefixes as shown below:
SW1(config)#ip prefix-list PREFIX_FILTER deny 0.0.0.0/8 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 10.0.0.0/8 le 32SW1(config)#ip prefix-list PREFIX_FILTER deny 100.64.0.0/10 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 127.0.0.0/8 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 169.254.0.0/16 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 172.16.0.0/12 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 192.0.2.0/24 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 192.88.99.0/24 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 192.168.0.0/16 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 198.18.0.0/15 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 198.51.100.0/24 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 203.0.113.0/24 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 224.0.0.0/4 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 240.0.0.0/4 le 32
SW1(config)#ip prefix-list PREFIX_FILTER deny 240.0.0.0/4 le 32
SW1(config)#ip prefix-list PREFIX_FILTER permit 0.0.0.0/0 ge 8
Step 2: Apply the prefix list filter inbound to each external BGP neighbor as shown in the example:
SW1(config)#router bgp xx
SW1(config-switch)#neighbor x.1.1.9 prefix-list PREFIX_FILTER in
SW1(config-switch)#neighbor x.2.1.7 prefix-list PREFIX_FILTER in
Route Map Alternative:
Step 1: Configure the route map referencing the configured prefix list above.
SW1(config)#route-map FILTER_PREFIX_MAP 10
SW1(config-route-map)#match ip address prefix-list PREFIX_FILTER
SW1(config-route-map)#exit
Step 2: Apply the route-map inbound to each external BGP neighbor as shown in the example:
SW1(config)#router bgp xx
SW1(config-switch)#neighbor x.1.1.9 route-map FILTER_PREFIX_MAP in
SW1(config-switch)#neighbor x.2.1.7 route-map FILTER_PREFIX_MAP in
SW1(config-switch)#end