802.1q question: port cost

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

If we I have port A and port B ocnnected from two bridges, is it
mandatory to set port cost the same on two bridges? What if not?

 

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

I can not find why it is necessary. However it's very possible the cost
has be changed by mistake. I think if it happens each bridge can not
compute path cost consisently, and result in differently views of path
cost, then trouble will surface. Just wonder if the specification
explictly state measures or guide lines to prevent that happen, or my
thought is just not right.

It's not a homework. If you really have experience will willing to
share.... Otherwise why bother?

 

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

thanks for pointing out the typo. Repost it

 

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

ask8y@yahoo.com wrote:

> If we I have port A and port B ocnnected from two bridges, is it
> mandatory to set port cost the same on two bridges? What if not?

Homework again?

 

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

ask8y@yahoo.com wrote:
> If we I have port A and port B ocnnected from two bridges, is it
> mandatory to set port cost the same on two bridges? What if not?
>

think of it this way: why on earth WOULD it be neccessary?

 

[Guest]

Archived from groups: comp.dcom.lans.ethernet (More info?)

ask8y@yahoo.com wrote:
> I can not find why it is necessary. However it's very possible the cost
> has be changed by mistake. I think if it happens each bridge can not
> compute path cost consisently, and result in differently views of path
> cost, then trouble will surface. Just wonder if the specification
> explictly state measures or guide lines to prevent that happen, or my
> thought is just not right.
>
> It's not a homework. If you really have experience will willing to
> share.... Otherwise why bother?
>

OK, if not hoemwaork, then clarify a few things-

why is the subject line "802.1q question: port cost". I don't get the
question. 802.1q is the spec for vlans - there IS no port cost option
involved with vlans. There is no path computation involved in that spec.

Please clarify what you are asking. Your question seems to be about
spanning tree, yet you refer to 802.1q.