From: William Swedberg (swedbergwp@xxxxxxxxx)
Date: Tue Aug 22 2000 - 13:28:43 GMT-3
The formula to calculate cost is
10^8/bandwidth=cost
If you have a 10mb interface the cost would be:
100,000,000/10,000,000 = 10
so to change this interface to a cost of 20 without
using the interface command "IP OSPF COST" do the
following:
100,000,000 / x = 20
100,000,000 = 20x
100,000,000/20 = x
5,000,000 = x
So on the interface use:
bandwidth 5000
By using the "ospf auto-cost reference-bandwidth XXXX"
command it changes the RefBw of 10^8 to a smaller or
larger value based on what is entered for XXXX.
(def is 100mb)
For instance, an ATM 155mb interface has the same cost
as a 100mb FDDI interface. The cost is 1. If you
change the RefBw to 1000mb, the FDDI is now 10 and the
ATM is 7.
Hope this helps.....
William Swedberg CCNP CCDP
--- peter brown <pita40@hotmail.com> wrote:
> Does anybody have a sample config where they
> modified ospf cost without
> using "ip ospf cost" command. I know it has to do
> with bandwidth
> manipulation ie "ospf auto-cost reference-bandwidth
> xxx" where xxx is
> bandwidth value. Please help.
>
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