Note
This is the default method for configuring IPv6 nexthop.In case of eBGP, when using IPv6 address, the configured nexthop will be unreachable and routes will not get downloaded to the routing table on the intermediate routers till this configuration is set on the interface on which the eBGP (MP-BGP) is configured.
Note
This configuration is only required for eBGP (MP-BGP) sessions. For iBGP sessions, this configuration is not required in cases where the IPv6 prefix has a valid IPv6 nexthop. However, in iBGP, when local routes are injected into BGP sessions, the above configuration is mandatory.
For eBGP (MP-BGP) sessions, to successfully reach the configured IPv6 nexthop, it is recommended that an IPv4-mapped IPv6 address be configured on the interface on which eBGP session will be created.
Note
When configuring the IPv4-mapped IPv6 address' mask length, use the formulae IPv4 Address Mask Length +
96.
In the above example, the configuration that must be applied to the interface, on which the eBGP session is to be enabled, is shown in the green box.
This is the consolidated configuration on the interface on which eBGP (MP-BGP) is configured. The interface is configured to use the user vrf vrf2.
interface Ethernet 0/23 vrf forwarding vrf2 ip address 192.168.23.2/24 ipv6 address ::ffff:192.168.23.2/120 no shutdown