For EIGRP to establish its neighbors, the K constant value to manipulate the
EIGRP metric must be the same. In the EIGRP metric calculation, the default for
the K value is set so that only the bandwidth and the delay of the interface
are used to calculate the EIGRP metric. At times, the network administrator
might want other interface values, such as load and reliability, to determine
the EIGRP metric. Therefore, the K values must be changed. Because only
bandwidth and delay are used in the calculations, the remaining K values are
set to a value of 0 by default.
 |
NOTE:
Cisco usually recommends that network administrators do not modify the
default metric of using bandwidth and delay.
|
However, the K values must be the same for all the routers or EIGRP
will not establish a neighbor relationship. An example of two routers with
mismatched K values is illustrated.

Modifying
the K values will affect how much, if any, of bandwidth, delay, reliability,
and load will have on the metric calculation. Modifying these K values will
have the following affect:
- K1 for bandwidth
- K2 for load
- K3 for delay
- K4 and K5 for reliability
Debugs and Verification
Figure
shows
the K values on RTR B have been changed to include load and reliability, along
with bandwidth and delay. K1, K2, K3, and K4 have all been set to 1. The
metric weights command shows that these values have been
modified. The first value is the type of service (TOS) which is not supported,
but must be included.
RTR A retains the default K values of K1 and K3
set to 1 for bandwidth and delay only, with all other K values set to 0. If
router such as RTR A is using the default, normally the metric
weights command would not be included in the configuration.
The command show ip eigrp neighbors on both RTR A and
RTB B would show an empty list. Troubleshooting this problem requires careful
scrutiny of the routers configuration.
Solution
The solution
is to configure the same K values on all routers in the EIGRP domain. Figure
shows the
modification made to RTR A to match the K values on RTR B. At this point both
routers will be able to establish a neighbor relationship and exchange routing
information.