6.5 Configuring EIGRP
6.5.3 The bandwidth-percent command
The bandwidth-percent command configures the percentage of bandwidth that may be used by EIGRP on an interface. By default, EIGRP is set to use only up to 50% of the bandwidth of an interface to exchange routing information. In order to calculate its percentage, the bandwidth-percent command relies on the value set by the bandwidth command.

Use the bandwidth-percent command when the bandwidth setting of a link does not reflect its true speed. The bandwidth value may be artificially low for a variety of reasons, such as to manipulate the routing metric, or to accommodate an oversubscribed multipoint Frame Relay configuration. Regardless of the reasons, configure EIGRP to overcome an artificially low bandwidth setting by setting the bandwidth-percent to a higher number. In some cases, it may even be set to a number above 100.

For example, assume that the actual bandwidth of a router's serial link is 64 Kbps, but the bandwidth value is set artificially low, to 32 Kbps. The figure shows how to modify EIGRP's behavior so that it limits routing protocol traffic according to the actual bandwidth of the serial interface. The example configuration sets serial 0's bandwidth-percent to 100 percent for the EIGRP process running in AS 24. Since 100 percent of 32 kbps is 32, EIGRP will be allowed to use half of the actual bandwidth of 64 Kbps.

Note that you can change EIGRP's percentage of bandwidth for IP, IPX, and AppleTalk with the following commands:

  • ip bandwidth-percent eigrp
  • ipx bandwidth-percent eigrp
  • appletalk eigrp-bandwidth-percent