From: Herbert Maosa (asawilunda@googlemail.com)
Date: Mon Feb 11 2008 - 19:18:09 ARST
I dont think you can avoid the FD as a route will not be considered as
candidate for Load Sharing if it does not meet the feasibility criteria.
I always do the maths on paper ( I really dont know if there are short cuts
), but I am quite comfortable with this so it does not really eat up any
time for me. If you are finding yourself trying so many different values, it
could be that you need a more solid base on the whole concept altogether.
Basically, this is how I approach this.
- Multiply the FD by X, where X is the traffic share count being
sought. This gives me what the worst metric should be for the load sharing
to work according to the given ratios.
- Work out X = BW(eigrp) + DLY(eigrp). The goal here is to find the
value for DLY(eigrp) as I never want to touch the BW. I only touch the BW
once in the path, as only the minimum bandwidth for the whole path is what
matters. So I often make the minimum bandwidth for the worst path to be
equal to the minimum bandwidth for the best path. That way I know that the
only discriminating factor is going to be the DLY. So, re-arranging work out
DLY(eigrp) = X - BW(eigrp).
- Once I find the value for DLY(eigrp), I can distribute it whichever
way I want on the links of this path, for as long as at all times I am
achieving the feasibility criteria.
At all times, remembering that DLY(eigrp) = Interface configured Delay * 256
BW(eigrp) = (10^7/interface bw in Kbps)*256
Also, remember that as you do the calculations, round down all real values (
floating point numbers ) as Cisco routers don't do floating point maths and
they round down at each step of the calculation.
regards,
Herbert.
Herbert.
On Feb 11, 2008 5:55 PM, Eggert, Scott <scott.eggert@berbee.com> wrote:
> Can anyone offer any insight on how to quickly determine the EIGRP
> metrics for a particular variance load sharing ratio. I struggled with
> the IE lab 8 EIGRP variance question and ended up trying different
> delays and bandwidth and ultimately calculating them to figure out the
> question. However, this could eat up time if this was the real test.
> Is there a quick rule or procedure for getting a particular metric and
> load sharing ratio? In particular, Is there a way to avoid going over
> the FD?
>
>
>
> Thanks.
>
>
>
>
>
>
>
> Scott Eggert
>
> Network Engineer
>
> CDW Berbee
> 4321 W College Ave Ste 400
> Appleton, WI 54914
>
> 920.996.3014
>
> 920.284.7619 - mobile
>
> 920.997.9419 - fax
>
> scott.eggert@berbee.com
>
> www.berbee.com
>
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