• How to Configure EIGRP on a Cisco Router


    When would you need this: When you are implementing a routing protocol on a large Internetwork and all the networking devices involved are Cisco devices.

    Special Requirements: EIGRP is a Cisco proprietary protocol. So, either all the routers in the Internetwork must be Cisco routers, or the routers should be EIGRP capable.

    Before starting, if you have not set the bandwidth of the interfaces, set them now. For correct routing decisions, you need to set the bandwidth for the serial interfaces depending on the WAN technologies that you are using. This is done using the following command on each serial interface:

    Router(config-if)#bandwidth XX

    where XX is the bandwidth of the WAN connection in kilobits per second.

    1. Enable EIGRP on the router with the command,

    Router(config)#router eigrp AS

    where AS is the Autonomous System number. The same AS number must be used for all the routers that you want to exchange routing information.

    2. Instruct the router to advertise the networks that are directly connected to it,

    Router(config-router)#network XXX.XXX.XXX.XXX

    XXX.XXX.XXX.XXX is the network id of a network that is directly connected to the router. Repeat this step for each network that is directly connected to the specific router that you are configuring. Remember that you need only to write the supernet of a group of subnets and the router will  automatically identify the subnets.

    For example, if the router is connected to the networks,,, and, you will need to do one ‘network’ command with the address

    3. Although it is not recommended, if you need to change the way the metrics of the routes are calculated, you can set them using the command:

    Router(config-router)#metric weights tos k1 k2 k3 k4 k5


    tos is the type of service index and the values of k1-k5 are used to calculate the metric using the following equation:

    metric=[k1*bandwidth + (k2*bandwidth) / (256-load) + (k3*delay)]*[k5/(reliability+k4)]

    the default values are k1=k3=1 and k2=k4=k5=0

    It is highly recommended that you leave the metric in the default values unless you are a highly experienced network designer.

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    Read the rest of the article in the Router Geek Book: Guide to Cisco Routers Configuration


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