How does EIGRP compute the metric?

[TCC_2]

Core Issue

Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco proprietary enhanced distance vector routing protocol, relying on the Diffused Update Algorithm (DUAL) to calculate the shortest path to a destination. It calculates a composite metric for the routes using multiple parameters involving bandwidth, delay, load, reliability and Maximum Transmission Unit (MTU). By default it uses only the bandwidth and delay parameters.

Resolution

For more detailed information on how EIGRP uses these parameters to compute the metric, refer to the EIGRP Metrics section of Enhanced Interior Gateway Routing Protocol.

For related information, refer to the Setting a Preferred Route by Influencing EIGRP Metrics.

[Prashant Sheshasayee]

EIGRP METRIC

• EIGRP Uses BW+ Delay+ load+ MTU+ Reliability
• By Default EIGRP uses Bandwidth and Delay in the metric calculation
• Formula with Default K Values (K1=1,K2=0,K3=1,K4=0,K5=0)
• BW=(10^7/lowest bandwidth in kbps)*256
• Delays=(sum of total delay/10)*256
• Metric=[K1*BW+((K2*BW)/(256-load))+K3*delay]