Differences between BGP 4 and BGP 4+

Address-family

Beyond IPv4, BGP now supports many protocols. The address-family command allows us to identify the network protocol.

The command address-family ipv6 specifies the IPv6 address family, and enters address family configuration mode.

router{conf:myconfig-rtg-bgp}address-family ipv6
router{conf:myconfig-rtg-bgp-ipv6}

The following command enables the neighbor to exchange prefixes for the specified family with the local router:

.. code-block:: cli
router{conf:myconfig-rtg-bgp-ipv6}neighbor A.B.C.D|X:X::X:X activate

It is possible to explicitly disable this feature with:

.. code-block:: cli
router{conf:myconfig-rtg-bgp-ipv6}neighbor A.B.C.D|X:X::X:X deactivate

The local and global next-hops

BGP 4 only provides a next-hop into the AS-PATH whereas BGP 4+ can add 2 next-hops: the local one and the global one.