router bgp 1
bgp router-id 1.1.1.1
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 2
R7(config-router)#address-family ipv6 unicast
R7(config-router-af)#neighbor 2.2.2.2 activate
what does the neighbor 2.2.2.2 activate under the ipv6 address family is used for ?
Hey Major,
Multi Protocol BGP can carry multiple different protocols over an underlying connection. This is how we use it with MPLS and things like IPv6. In MP BGP we have to activate an address family if we want that address family to be used as part of the BGP exchange. IPv4 is activated by default, though can be deactivated. When you activate IPv6 you are telling BGP you want it to be able to send IPv6 information.
@Network_Eric
R7(config-router)#address-family ipv6 unicast
R7(config-router-af)#neighbor 2.2.2.2 activate
what does this command meaning ? i dont understand . how could we have ipv4 neighbor under the ipv6 address family ? if we have ipv4 address family we need ipv4 neighbor and if we have ipv6 address family we need ipv6 neighbor. but the opposite is something i dont understand at all
Hey Major,
Multi Protocol BGP is a really big topic to cover, but for our purposes here I’ll try to sum up an answer for your question. BGP allows you to exchange multiple protocols across a single peer relationship. So, instead of needing, as you proposed, an IPv4 and IPv6 peering, you can run it all over an IPv4 connection. This includes Unicast and Multicast traffic (which can be modified separately), or even to exchange MPLS VPN information.
So, there are some issues that happen when you deploy an IPv4 neighbor with IPv6 information, you have to do things like modify next hop information with a routemap, but it it allows a great deal of flexibility.