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AD and FD values calculation in EIGRP

HI

Can anyone explain me how to calculate the above vlaues in EIGRP as i am confused regarding this.

And how does eigrp selects sucessor and feasiable sucessor.

Thanks

Mahmood

3 REPLIES

Re: AD and FD values calculation in EIGRP

Hi Mahmood,

First the metric is calculated to reach a particular destination. Now if there are more than 2 routes to reach a particular destination metric ill be calculated for both the routes to reach the destination using a particular formula which is

(10000000/minimum bandwidth + total delay) *256

Now once the metric is calculated for both the routes the route having the minimum metric will be considered as the feasible distance and will be placed in the routing table.

Now it will check a criteria if the second route can be placed as a feasible successor or not. For that EIGRP will calculate the reported distance for second route which is calculatd using the same formula with only difference that it will be calculated form the upstream router towards the destination. If the reported distance metric is less than the metric calculated for feasible distance then the second route will be placed as a feasible successor in eigrp topology table.

Have a look at thi link for more details

http://www.cisco.com/warp/customer/103/eigrp-toc.html#eigrpmetrics

HTH, if yes please rate the post.

Ankur

Re: AD and FD values calculation in EIGRP

HI

Ankur thanks for u r reply.can u explain me in more detail.

Thanks

Mahmood

Re: AD and FD values calculation in EIGRP

Hi Mahmood,

Can you be specific what you did not understood from the previous explaination so that I can try stressing on that point.

Also I am not sure if you got a chance to look at the link which I posted in my previous mail.

I am again pating the link which is a publick link now and does not need CCO login so just read the "EIGRP METRIC" section as it will explain everything in detail with topolgy also.

http://www.cisco.com/warp/public/103/eigrp-toc.html#eigrpmetrics

HTH, if yes please rate the post.

Ankur

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