RE: EIGRP Composite Metric Calculation

From: Sheahan, John (John.Sheahan@priceline.com)
Date: Fri Apr 29 2005 - 12:07:50 GMT-3


That excel spreadsheet is awesome!

Thanks alot

  _____

From: Chad Hintz [mailto:ccie_2b2004@yahoo.com]
Sent: Friday, April 29, 2005 9:48 AM
To: Paresh Khatri; johnsheahan@charter.net; Sheahan, John;
ccielab@groupstudy.com
Subject: RE: EIGRP Composite Metric Calculation

Hi Guys,

This is a spreadsheet for calculation that I recieved from one our SEs
that put this together from a networkers presentation. This shows all
the calcuations.

HTH,

Chad

Paresh Khatri <Paresh.Khatri@aapt.com.au> wrote:

        Hi John,

        If the BW is 10,000kbps and the cumulative delay is 7000
microseconds, you get the following:

        Metric = 256*(10^7/10^4) + 256*7000/10
        = 256*1000 + 256 * 700
        = 256000 + 179200
        = 435200

        which matches with what you are seeing...

        Note that the delay value you use is in tens of microseconds, so
you have to divide the value by 10 before using it in the formula.

        HTH,
        Paresh.

        -----Original Message-----
        From: johnsheahan@charter.net [mailto:johnsheahan@charter.net]
        Sent: Friday, 29 April 2005 10:01 AM
        To: Paresh Khatri; Sheahan, John; ccielab@groupstudy.com
        Subject: Re: EIGRP Composite Metric Calculation

        Thanks for the help!

        On R1, the delay for 172.16.1.0/24 is 1000ms, the bandwidth is
10000kb.
        The outgoing interface on R2 is the same.

        The network 172.16.1.0/24 is actually the Loopba! ck interface 0
on R3. This
        interface shows delay=5000ms and the bandwidth= 8,000,000kb.

        ----- Original Message -----
        From: "Paresh Khatri"
        To: "Sheahan, John" ;
        Sent: Thursday, April 28, 2005 7:19 PM
        Subject: RE: EIGRP Composite Metric Calculation

> 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
> th! ree 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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