Re: STP Cost

Calculate the STP using pen and paper and answer will be obvious.

Now, that said, this is actually very well covered in the following material:

http://www.ciscopress.com/bookstore/product.asp?isbn=158720181X

To take this further on the list, I would kindly ask you to be a
little bit more specific in your question.

Kind regards,
Marko.

--
Marko
CCIE #18427 (SP)
My network blog: http://cisco.markom.info/
On Fri, Oct 16, 2009 at 20:15, Donald Virgil <d.virgil88_at_gmail.com> wrote:
> I am having a hard time understanding STP cost and how links get chosen over
> others.
>
> Example
>
> SW1----- SW2
> B | B  B  B  B  B / B  |
> B | B  B  B  B / B  B  |
> B | B  B  B / B  B  B  |
> B SW3-----SW4
>
>
> SW3 is root for VLAN 10, 20, 30, 40
> SW2 is root for VLAN 50, 60.
>
> When I set the STP cost to 5 on the trunk between SW1 and SW3 and the trunk
> between SW2 and SW3 fail, the STP root ports on SW2 is the trunk from SW2 to
> SW1.
>
> I am confused as to why the cost has to be set on the link between SW1 and
> SW3 to get this behavior instead of the link between SW1 and SW2.
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