From: Jim Newton (jnewton@xxxxxxxxxxxxxxx)
Date: Wed Mar 20 2002 - 14:38:29 GMT-3
My bad.....
I made a typo on the formula, it should be a * not a + between the first and
second expressions, but to clear up everything on page 243 on Doyle Vol 1 it
says that if K5 is zero that last expression is not used.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of Jim
Newton
Sent: Wednesday, March 20, 2002 11:14 AM
To: Rising, Danny; ccielab@groupstudy.com
Subject: RE: CCIE Question regarding metrics and K values
Thinking back to my algebra, all multiplication and division operations are
performed before all subtraction and addition operations, unless something
is in parenthesis.
So looking at the formula, you get:
[(K1 * Bandwidth) + [(K2 * Bandwidth / (256 - Load)] + (K3 * Delay)] + [K5 /
(Reliability + K4)]
So because the part with K5 and K4 is in its own set of brackets, if either
is a zero, that set of brackets just disappears, and the first part of the
formula is still counted. Looking at the first part if K1 and K3 are one
then the first and third sections would get used, but the middle section
would drop out because K2 is a zero. If you wanted to take load into
consideration, you would make K2 a one.
Someone please correct me if I am wrong.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Rising, Danny
Sent: Wednesday, March 20, 2002 10:39 AM
To: 'ccielab@groupstudy.com'
Subject: CCIE Question regarding metrics and K values
> These facts are given...
>
> To determine EIGRP metric the following formula is used.
>
> metric = [K1 * bandwidth + (K2 * bandwidth) / (256 - load) + K3 * delay] *
> [K5 / (reliability + K4)]
>
> Default values are as follows...
>
> K1 = 1
> K2 = 0
> K3 = 1
> K4 = 0
> K5 = 0
>
> Capmark uses
>
> K1 = 0
> K2 = 1
> K3 = 1
> K4 = 1
> K5 = 0
> K6= 0
>
> In both cases, K5 is equal to 0. 0 divided by anything is zero and 0
> multiplied by anything is zero. So regardless of other values, if K5=0
> then metric=0. Cisco says this in the white paper on EIGRP
>
> For default behavior, you can simplify the formula as follows:
>
> metric = bandwidth + delay
>
> Combine this formula with the scaling factors and you have:
>
> [(10^7/min bandwidth) + sum of delays] * 256
>
> Just how in the heck do they get metric = BW + Delay if the "reliability
> modifier" is always 0?
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