Re: OSPF cost - LAN segment

It could be, but does not have to be.
When computing a path, you're always considering outgoing costs.
So if you have a connection:
R3 (s1/0) ======= (s1/0) R2

And R2's interface has a cost of 500, and R3's has a cost of 1000 (e.g.
manual config) then the cost will be different as you pointed out.

But that signifies bad design in most cases. There are cases where this is
expected, but most of the time you should have the same costs.

If it is all default config, there probably will be a different cost,
because when you use clock rate on DCE interface, bandwidth will be set to
the clock rate and cost will be huge. But on DTE interface, it will still be
1536kbps. so you'd need to synchronize bandwidth parameters there

On Thu, May 21, 2009 at 5:06 AM, Welly Kamarudin <welly.wewe_at_gmail.com>wrote:

> Hi all,
>
> May I know a little bit detail about ospf cost,
>
> For example I have topology like below
>
> R1 (fa0/0) |------ SW1------| (e0/0) R3 (s1/0) ======= (s1/0) R2
> cost ?
>
> ------| ethernet segment
> === serial interfaces
>
> Using default bandwidth reference.
> I want to ask what will be the cost on the LAN segment between R1 and R3
> Is it true that, there will be two different costs there depending on from
> which point we look the routing table?
> So for example I put loopback on R2 and R1.
> The cost from R1 when try to reach loopback on R2 will be lower if I
> compare
> with the cost from R2 when try to reach loopback R1.
>
>
> Thanks for clarifying
> Welly
>
>
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