command displays parameters, filters, and network information concerning the routing protocols in use on the router. The algorithm used to calculate the routing metric for IGRP is shown in the graphic. It defines the value of the K1-K5 metrics and provides information concerning the maximum hop count. The metric K1 represents bandwidth and the metric K3 represents delay. By default the values of the metrics K1 and K3 are set to 1, while K2, K4 and K5 are set to 0.

This composite metric is more accurate than the hop count metric that RIP uses when choosing a path to a destination. The path that has the smallest metric value is the best route.

The metrics that IGRP uses are:

• Bandwidth – The lowest bandwidth value in the path
• Delay – The cumulative interface delay along the path
• Reliability – The reliability on the link towards the destination as determined by the exchange of keepalives
• Load – The load on a link towards the destination based on bits per second
• MTU – The Maximum Transmission Unit value of the path.

IGRP uses a composite metric. This metric is calculated as a function of bandwidth, delay, load, and reliability. By default, only bandwidth and delay are considered. The other parameters are considered only if enabled via configuration. Delay and bandwidth are not measured values, but are set via the delay and bandwidth interface commands. The show ip route command in the example shows the IGRP metric values in brackets. A link with a higher bandwidth will have a lower metric, and a route with a lower cumulative delay will have a lower metric.

Web Links Configuring IGRP http://www.cisco.com/en/US/products/sw/ iosswrel/ps1831/ products_configuration_guide_ chapter09186a00800d97f6.html