RE: EIGRP Composite Metric Calculation

From: Paresh Khatri (Paresh.Khatri@aapt.com.au)
Date: Thu Apr 28 2005 - 20:19:59 GMT-3


Hi,

What does the output of 'sh ip eigrp topology 172.16.1.0 255.255.255.0' indicate as the bandwidth and delay on R1 ?

Paresh.

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Sheahan, John
Sent: Friday, 29 April 2005 07:15 AM
To: ccielab@groupstudy.com
Subject: EIGRP Composite Metric Calculation

I am trying to manually calculate the EIGRP Composite metric in a basic
lab setup. My numbers aren't coming out to what the book says. I have
three routers connected in togther in a row with the ethernet ports as
follows:

R1----------R2-----------R3

R3 has a loopback address of 172.16.1.0/24.

I notice that when I do a "show ip route 172.16.1.0" on R1, I see the
reliability to this route as 131/255 and a metric of 435200 to that
route.

When I try and do the calculation for the composite metric (CM), I am
getting the wrong answer and was wondering if I have to include the
reliability (131/255) into my calculation?

The formula I am using is:

DELAY_sum = The sum of the delay on outgoing interfaces only to the
destination route 172.16.1.0/24

BW_min = 10 to the 7th power divided by the smallest bandwidth to the
destination route 172.16.1.0/24

CM = (256 x BW_min) + (256 x DELAY_sum)

My calculations would be:

CM = (256 x 10000) + (256 x 7000)

CM = 4,352,000 which is off by one zero based on the metric of 435200
reported by the R1 router.

Can anyone give me a hint as to what I'm doing wrong?

Thanks!



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