Phil,
Doyle (Routing TCP/IP, volume 1) has a slightly more useful explanation.
In the IGRP chapter (he doesn't dicuss EIGRP metrics much as he just refers
back to the IGRP formula which is the same), he explains "If k5 is set to
0, the [k5/(reliability + k4)] term is not used". It implies that there
are essentially two different formulae:
[k1*BW + (k2 * BW)/(256-load) + k3 * delay] * [k5/(reliability + k4)] if k5
<> 0, and
[k1*BW + (k2 * BW)/(256-load) + k3 * delay] if k5 = 0.
I agree with you on the maths :-)
JMcL
---------------------- Forwarded by Jenny Mcleod/NSO/CSDA on 16/01/2001
08:52 am ---------------------------
Phil Barker <[EMAIL PROTECTED]>@groupstudy.com on 16/01/2001
04:46:09 am
Please respond to Phil Barker <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
cisco GroupStudy <[EMAIL PROTECTED]>
cc:
Subject: RE: CertificationZone White Paper EIGRP ?
Thanks for that link Glen,
It looks now like its me against the world.
In the UK I would call K5 the nominator of this part
of the equation and "reliability + k4" would be the
denominator.
If the nominator = 0 then the expression k5/(rel + k4)
will be 0. As a result when multiplying by anything on
the left will result in 0.
I'm wondering if there is a difference in algebraic
notation batween USA and UK or if I need to go back to
school ?
Regards,
Phil.
--- Glenn Johnson <[EMAIL PROTECTED]> wrote: >
http://www.cisco.com/warp/public/103/eigrp1.html
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of
> Phil Barker
> Sent: Monday, January 15, 2001 11:59 AM
> To: cisco GroupStudy
> Subject: CertificationZone White Paper EIGRP ?
>
>
>
> I'm having trouble with the equation referenced on
> page 5 (A4) concerning the metric calculation.
> Ref Don Dettmore.
>
> If this equation is correct as it stands and
> K2=K4=K5=0
> Then the Right Side of the equation will be 0, which
> when multiplied by whatever on the left side will
> equal 0. i.e metric = 0. I'm guessing a little that
> these two sides should be added together not
> multiplied ? Can anyone verify this ?
>
> I've cross checked this with Ivan Pepelnjak' book on
> EIGRP. Chapter 1, Page 10 "Computing a Composite
> Metric" appears to verify that the White Paper is
> CORRECT. They both suggest that if K5 = 0 then the
> Composite Metric = 0 ???
>
> Ivan also suggests that if all K-Values are set to
> zero then the composite metric is always 1 ?
>
> Wether or not you add or multiply both sides
> together
> the composite metric will = 0.
>
> Anyway, there is also a typo below 108 should read
> 10^8
>
>
>
> >>SNIP
> This differs from the bandwidth usage in OSPF, in
> which route cost, by default, derives from the sum
> of
> interface costs along the path. OSPF interface cost
> defaults to 108/interfaceBandwidth, where
> interfaceBandwidth is 1544 or the value of the
> interface bandwidth commands (with a value in
> kilobits).
>
>
> >>END SNIP
>
>
> Any thoughts ?
>
> Phil.
>
>
>
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