We will suppose that our initial scenario is an exchange point with three BGP capable routers, named RA, RB and RC. Each of the BGP speakers generates some routes (with the network command), and establishes BGP peerings against the other two routers. These peerings have In and Out route-maps configured, named like “PEER-X-IN” or “PEER-X-OUT”. For example the configuration file for router RA could be the following:
#Configuration for router 'RA' ! hostname RA password **** ! router bgp 65001 no bgp default ipv4-unicast neighbor 2001:0DB8::B remote-as 65002 neighbor 2001:0DB8::C remote-as 65003 ! address-family ipv6 network 2001:0DB8:AAAA:1::/64 network 2001:0DB8:AAAA:2::/64 network 2001:0DB8:0000:1::/64 network 2001:0DB8:0000:2::/64 neighbor 2001:0DB8::B activate neighbor 2001:0DB8::B soft-reconfiguration inbound neighbor 2001:0DB8::B route-map PEER-B-IN in neighbor 2001:0DB8::B route-map PEER-B-OUT out neighbor 2001:0DB8::C activate neighbor 2001:0DB8::C soft-reconfiguration inbound neighbor 2001:0DB8::C route-map PEER-C-IN in neighbor 2001:0DB8::C route-map PEER-C-OUT out exit-address-family ! ipv6 prefix-list COMMON-PREFIXES seq 5 permit 2001:0DB8:0000::/48 ge 64 le 64 ipv6 prefix-list COMMON-PREFIXES seq 10 deny any ! ipv6 prefix-list PEER-A-PREFIXES seq 5 permit 2001:0DB8:AAAA::/48 ge 64 le 64 ipv6 prefix-list PEER-A-PREFIXES seq 10 deny any ! ipv6 prefix-list PEER-B-PREFIXES seq 5 permit 2001:0DB8:BBBB::/48 ge 64 le 64 ipv6 prefix-list PEER-B-PREFIXES seq 10 deny any ! ipv6 prefix-list PEER-C-PREFIXES seq 5 permit 2001:0DB8:CCCC::/48 ge 64 le 64 ipv6 prefix-list PEER-C-PREFIXES seq 10 deny any ! route-map PEER-B-IN permit 10 match ipv6 address prefix-list COMMON-PREFIXES set metric 100 route-map PEER-B-IN permit 20 match ipv6 address prefix-list PEER-B-PREFIXES set community 65001:11111 ! route-map PEER-C-IN permit 10 match ipv6 address prefix-list COMMON-PREFIXES set metric 200 route-map PEER-C-IN permit 20 match ipv6 address prefix-list PEER-C-PREFIXES set community 65001:22222 ! route-map PEER-B-OUT permit 10 match ipv6 address prefix-list PEER-A-PREFIXES ! route-map PEER-C-OUT permit 10 match ipv6 address prefix-list PEER-A-PREFIXES ! line vty !