Activate IPv6 Address Family for a Dynamic BGP Neighbors Using Default VRF

To configure multi-protocol BGP for exchanging IPv6 prefixes over IPv4 BGP Sessions for Dynamic BGP Neighbors using default VRF, do the following:

Access global configuration mode.
```
 device# configure terminal 
```
Access BGP configuration mode.
```
device(config)# router bgp
```
Specify the autonomous system in which your device resides.
```
device(config-bgp-router)# local-as 1000
```
Enable exchanging IPv6 prefixes over IPv4 for BGP.
```
device(config-bgp-router)# peer-group ipv6prefix-over-ipv4peer 
```
Note

When the IPv6 address family is already activated under a peer-group and the command peer-group ipv6prefix-over-ipv4peer is executed, the Neighbor NLRI Negotiation capabilities are modified from IPv4 Unicast Routes to IPv4 and IPv6 Unicast Routes. This will reset the existing BGP IPv4 connections, those that are mapped to a peer-group and have IPv6 address family enabled.

This reset also happens when IPv6 Address Family is already activated under a peer-group, and CLI peer-group ipv6prefix-over-ipv4peer is being disabled.

This enables the exchanging of IPv6 addresses over IPv4 BGP sessions. This configuration only applies to those BGP neighbors who are members of a peer group.

Navigate into the Peer Group context.

device(config-bgp-router)# neighbor pgMain peer-group
	%Warning: Please activate Peer-group for IPv6 address-family

Specify the autonomous system in which the remote peer-group resides. Assign the remote AS to the peer-group.
```
device(config-bgp-router)# neighbor pgMain remote-as 1001
```
Specify the IPv4 address range assigned to the dynamic BGP neighbors and assign that range to the peer group.
```
device(config-bgp-router)# listen-range 10.0.2.0/24 peer-group pgMain 
```

Configure the IPv6 address family for the default VRF.

device(config-bgp-router)# address-family ipv6 unicast
device(config-bgp-ipv6u)#

Activate the IPv6 Address Family for the dynamic BGP neighbors.
```
device(config-bgp-ipv6u)# neighbor pgMain activate
```

The following is a consolidation of tasks to perform to activate IPv6 address family for a BGP peer using default VRF.

router bgp
local-as 1000
peer-group ipv6prefix-over-ipv4peer
neighbor pgMain peer-group
neighbor pgMain remote-as 1001
listen-range 192.0.2.0/24 peer-group pgMain
address-family ipv6 unicast 
neighbor pgMain activate