Basic Eigrp Configuration

Basic Eigrp Configuration

After EIGRP process is configured on the router, the router starts to exchange EIGRP hello packets over the multicast address 224.0.0.10.Eigrp neighborships form between routers after they get each other's hello packet.

Some rules for these neighborships:

-      The receiving router compares the source address of the hello packet with the IP address of the interface where the packet was received.These IP addresses must be in same subnet.

-      The routers compares the K constant values of each other.These K values must match.

-      The routers must use the same AS number for Eigrp.

Basic Eigrp configuration between two  routers:

Router1:

interface Loopback0

 ip address 192.168.0.1 255.255.255.255

!

interface FastEthernet0/0

 ip address 192.168.12.1 255.255.255.0

router eigrp 1

 network 192.168.0.0 0.0.255.255

 no auto-summary

Here is the basic Eigrp configuration for Router2

interface Loopback0

 ip address 192.168.0.2 255.255.255.255

!

interface FastEthernet0/0

 ip address 192.168.12.2 255.255.255.0

router eigrp 1

 network 192.168.0.0 0.0.255.255

 no auto-summary

Verification:

R1#show ip eigrp neighbors

IP-EIGRP neighbors for process 1

H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq

                                            (sec)         (ms)       Cnt Num

0   192.168.12.2            Fa0/0             13 00:25:40  286  1716  0  36

The explanations of the “show ip eigrp neighbors” command output:

H— The list of the neighbors.

Address— The IP address of the neighbors.

Interface— The interface that the router communicate with the neighbor.

Hold— The hold timer for the neighbor. If this timer reaches 0, the neighbor relationship becomes down

Uptime— shows the how long this neighbor has been established.

SRTT (Smooth Round Trip Time)— The average time interval for EIGRP packet is sent and received.

RTO (Round Trip Timeout)— How long the router will wait to retransmit the EIGRP reliable packet if acknowledgment is not received.

Q Count— The number of EIGRP packets waiting to

 be sent to the neighbor.

Sequence Number— The sequence number of the last EIGRP reliable packets being

received from the neighbor.