Composite metric and K values in a Cisco EIGRP domain

Step by Step Guide Configuration Enhance Interior Gateway Routing Protocol (Cisco EIGRP)

Cisco proprietary protocol EIGRP contains various types of metric quantity, such as:

  • Bandwidth
  • Delay
  • Reliability and Load, (not used by EIGRP)

EIGRP uses composite metric and “K” values to calculate preferred path to a destination.

To verify metric value used by router, use:

show interface

show interface S0//0/0 

See the diagram below for metric info:

Delay and bandwidth are measured metrically when used by router interface configured with Cisco EIGRP.

Default metric values on a Cisco router interface are adjustable, however Cisco advise not to change them as this may reduce performance.  Before attempting such alterations consult knowledgeable designer.

Cisco EIGRP only uses that bandwidth and delay for its routing metrics.  Cisco recommends not tempering with load and reliability.

Understanding Metric K values

The Default Cisco devices K1 and K3 are set to 1 while K2, K4 and K5 are set to 0:

Default Metric Changes
K1 bandwidth 1
K2 load 0
K3 delay 1
K4 reliability 0
K5 reliability 0

 

How to configured Cisco EIGRP Metric

When change K value, it is important to plan before implementation.

Note that mismatched K values between connected routers configured with EIGRP can harm neighbour relationships and have negative impact on network convergence.

To apply K value changes to entire routers in EIGRP domain or to router sharing the same link, Use:

  • ISPConnected>en
  • ISPConnected#conf t
  • ISPConnected(config)#router eigrp 1
  • ISPConnected(config-router)#metric weights 0 20 50 10 60 60

%DUAL-5-NBRCHANGE: IP-EIGRP 1: Neighbor 10.10.0.1 (Serial0/0/0) is down: K-value mismatch

%DUAL-5-NBRCHANGE: IP-EIGRP 1: Neighbor 10.10.0.1 (Serial0/0/0) is down: K-value mismatch

%DUAL-5-NBRCHANGE: IP-EIGRP 1: Neighbor 10.10.0.1 (Serial0/0/0) is down: K-value mismatch

The above configuration was applied to ISP router connected to London. It starts with a metric weight of zero which is supported by TOS (Type of Service).

Number assigned range from 0 – 256 and K to the value of zero invalid.

How to configured Cisco EIGRP Metric

You can’t change K values on single routers in a EIGRP domain.  They must be changed on both routers simultaneously. Should errors occur, the console terminal will inform you that neighbour relation has not been set up.

London router interface is down because it has not been configured with one used in ISP (metric).

To resolve the K value error, configure all connected router with same k value.

Alternatively, you could return K to its EIGRP default weight value K1=1, K2=0, K3=1, K4=0, K5=0 using command specified below:

  • ISPConnected#conf t
  • ISPConnected(config)#router eigrp 1
  • ISPConnected(config-router)#no metric weights 0 20 50 10 60 60

To verify changes, use:

show running-config

show ip protocol

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