IPv6 EIGRP static neighbors

It is possible to configure a static EIGRP adjacency when using IPv6. This can be achieved as follows:

Router(config-rtr)#neighbor FE80::5054:FF:FE0C:D5D7 gigabitEthernet 0/1

This command is applied within the IPv6 EIGRP router configuration mode. The command creates an adjacency with the router with the link local address of FE80::5054:FF:FE0C:D5D7.

The command must also be applied to the IPv6 EIGRP neighbor with the link local address of the local router as well to complete the adjacency.

Note what happens when this command is applied to an IPv6 EIGRP router that has already automatically established a neighbor adjacency:

Router(config-rtr)#neighbor FE80::5054:FF:FE0C:D5D7 gigabitEthernet 0/1
Router(config-rtr)#
*Mar  8 07:44:38.929: %DUAL-5-NBRCHANGE: EIGRP-IPv6 1: Neighbor FE80::5054:FF:FE0C:D5D7 (GigabitEthernet0/1) is down: Static peer replaces multicast

Notice the SYSLOG message indicates that the static peer replaces the multicast peering mechanism. The neighbor adjacency is considered down because the neighbor is still expecting peering to be established via multicast. Notice what syslog message appears on the neighbor:

``*Mar 8 07:44:38.720: %DUAL-5-NBRCHANGE: EIGRP-IPv6 1: Neighbor FE80::5054:FF:FE0E:CFF3 (GigabitEthernet0/1) is down: Interface PEER-TERMINATION received`

It has received a PEER-TERMINATION from its neighbor. To reestablish the adjacency using static peering, the following command is applied to the neighbor as well:

Router(config-rtr)#neighbor FE80::5054:FF:FE0E:CFF3 gigabitEthernet 0/1
Router(config-rtr)#
*Mar  8 07:45:43.001: %DUAL-5-NBRCHANGE: EIGRP-IPv6 1: Neighbor FE80::5054:FF:FE0E:CFF3 (GigabitEthernet0/1) is up: new adjacency

Note the new adjacency that forms.

Only link local IPv6 addresses can be used to establish static EIGRP neighbors in IPv6. If you attempt to try to use a global unicast address, the following error message will appear:

Router(config-rtr)#neighbor 2001::1 gigabitEthernet 0/1
%EIGRP: Only link-local addresses allowed with local static neighbors in IPv6.
Router(config-rtr)#

Links:

https://networklessons.com/ipv6/how-to-configure-ipv6-eigrp-on-cisco-ios-router