3.7.f Implement and troubleshoot multiproctocol BGP

3.7.f [i] IPv4, IPv6, VPN address-family

when you know you’re going to use multiprotocol bgp, as in mpls vpn, it is perhaps a good practice to define and place the specific address family commands in their proper cubicles as you configure…

for instance, note below the ipv4 config is not delimited, while the vpnv4 config necessarily is:

router bgp 1
no synchronization
bgp log-neighbor-changes
neighbor 7.7.7.7 remote-as 1
neighbor 7.7.7.7 update-source Loopback0
no auto-summary
!
address-family vpnv4
neighbor 7.7.7.7 activate
neighbor 7.7.7.7 send-community extended
exit-address-family

ivan has an instructive article about this here… http://blog.ioshints.info/2008/06/use-explicit-address-family-ipv4-in-bgp.html

further, it might prove useful when simply using plain bgp to get in the habit of using the address family configuration…

there is also a way to automatically convert this after the fact:

PE1(config-router)#bgp upgrade-cli
You are about to upgrade to the AFI syntax of bgp commands

Are you sure ? [yes]: y
PE1(config-router)#do sh run | b bgp
router bgp 1
bgp log-neighbor-changes
neighbor 7.7.7.7 remote-as 1
neighbor 7.7.7.7 update-source Loopback0
!
address-family ipv4
neighbor 7.7.7.7 activate
no auto-summary
no synchronization
exit-address-family
!
address-family vpnv4
neighbor 7.7.7.7 activate
neighbor 7.7.7.7 send-community extended
exit-address-family

how about that?