EIGRP

DUAL: The Diffusing Update ALgorithm, a Bellman-Ford based routing algorithm used by EIGRP.

EIGRP – Routing Information Protocol is widely deployed interior gateway routing protocol. EIGRP was developed in the 1990’s. EIGRP is a distance-vector protocol and is based on the DUAL algorithms. As a distance-vector protocol, the EIGRP router send updates to its neighbors as networks change, thus allowing the convergence to a known topology.

eigrpd supports EIGRP as described in RFC7868

EIGRP Configuration

router eigrp (1-65535) [vrf NAME]: The router eigrp command is necessary to enable EIGRP. To disable EIGRP, use the no router eigrp (1-65535) command. EIGRP must be enabled before carrying out any of the EIGRP commands. Specify vrf NAME if you want eigrp to work within the specified vrf.

network NETWORK

Set the EIGRP enable interface by network. The interfaces which have addresses matching with network are enabled.

This group of commands either enables or disables EIGRP interfaces between certain numbers of a specified network address. For example, if the network for 10.0.0.0/24 is EIGRP enabled, this would result in all the addresses from 10.0.0.0 to 10.0.0.255 being enabled for EIGRP. The no network command will disable EIGRP for the specified network.

Below is very simple EIGRP configuration. Interface eth0 and interface which address match to 10.0.0.0/8 are EIGRP enabled.

!
router eigrp 1
 network 10.0.0.0/8
!

passive-interface (IFNAME|default)

This command sets the specified interface to passive mode. On passive mode interface, all receiving packets are ignored and eigrpd does not send either multicast or unicast EIGRP packets except to EIGRP neighbors specified with neighbor command. The interface may be specified as default to make eigrpd default to passive on all interfaces.

The default is to be passive on all interfaces.

How to Announce EIGRP route

Redistribute routes into EIGRP:

redistribute <bgp|connected|isis|kernel|ospf|rip|static|table> [metric (1-4294967295) (0-4294967295) (0-255) (1-255) (1-65535)]

Show EIGRP Information

show ip eigrp [vrf NAME] topology

Display current EIGRP status.

eigrpd> **show ip eigrp topology**
# show ip eigrp topo

EIGRP Topology Table for AS(4)/ID(0.0.0.0)

Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply
       r - reply Status, s - sia Status

P  10.0.2.0/24, 1 successors, FD is 256256, serno: 0
       via Connected, enp0s3

show ip eigrp [vrf NAME] interface: Display the list of interfaces associated with a particular eigrp instance.

show ip eigrp [vrf NAME] neighbor: Display the list of neighbors that have been established within a particular eigrp instance.

EIGRP Debug Commands

Debug for EIGRP protocol.

debug eigrp packets

Debug eigrp packets

debug eigrp will show EIGRP packets that are sent and received.

debug eigrp transmit

Debug eigrp transmit events

debug eigrp transmit will display detailed information about the EIGRP transmit events.

show debugging eigrp

Display eigrpd’s debugging option.

show debugging eigrp will show all information currently set for eigrpd debug.