EIGRP: Timers, k-values, "neighbor" command


EIGRP Timers

The EIGRP timers are configured (a bit non-intuitive commands from my point of view) on the interface towards the EIGRP neighbor:

Set the Hello timer for the EIGRP 100 process:

(config-if)#ip hello-interval eigrp 100 30

Set the Dead timer for the EIGRP 100 process:

(config-if)#ip hold-time eigrp 100 120

Check the configured Timers using the command:

#show ip eigrp interface static


EIGRP "show neighbors" command

Cisqueros1#show ip eigrp neighbors 
EIGRP-IPv4 Neighbors for AS(100)
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
                                            (sec)         (ms)       Cnt Num
0   10.1.12.2               Se1/0.12         115 00:10:04   26   200  0  32

How to interpret this output:

H - The order in which neighbors were found, starting from 0

Address - Neighbors IP

Interface - from where we see the Neighbor

Holdtime - how long we have left before we declare the neighbor down (if no Hello is received)

Uptime - How long since we first found out about the neighbor

SRTT - Smooth Round Trip Time. time required for EIGRP packet to reach the neighbor and receive the ACK

RTO - Retransmission Timeout - how long before the packet is re-transmitted

Q Count - Number of packets in the EIGRP queue

SeqNum - Sequence Number of the last received EIGRP packet


EIGRP Metric - K Values

5 K-Values are used to calculate the EIGRP Metric. It´s pretty important to know at least which one is which of the K values:

K1 - Bandwidt
K2 - Load
K3 - Delay
K4 - Reliability
K5 - Reliability

Metric = (K1*BW + (K2*BW)/(256-Load) + K3*Delay) * 256

By default K2 = K4 = K5 = 0, so the Metric depends on the Bandwidth and Delay only

If you need the EIGRP Metric to depend on some other values the command is (ToS should be left 0):

 (config-router)#metric weight tos k1 k2 k3 k4 k5

¡¡¡BE CAREFULL BECAUSE K VALUES NEED TO MATCH BETWEEN THE EIGRP NEIGHBORS!!!

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