Re: STP Root Port Election..

Jitenda,

Just to expand on Andrews email.

Stp selects one designated port per segment to forward traffic the other
ports go into no-designated and block.

The ports on the root bridge are all designated because the cost is zero.

HTH

Tony

On Sun, Jun 14, 2009 at 7:40 AM, andrew <andrew.coates_at_internode.on.net>wrote:

> Hi,
>
> Root port:
>
> Lowest cost to root
> Lowest sender bridge ID ( priorty+mac)
> Lowest sender port ID (priority+portnumber)
>
> IN 802.1D
> A designated port is any port that isn't a root port, blocking port or
> disabled port.
>
> In the situation where two switches are connected to the same segment that
> isn't the segment with the root port then the above is again used to
> determine which port is blocking and which is the Designated.
>
> The root bridge has all ports designated.
>
>
> cheers
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> Jitendra Anbu
> Sent: Monday, June 15, 2009 12:23 AM
> To: CCIE R/S, Groupstudy
> Subject: STP Root Port Election..
>
> Hi all,
>
> When electing the root port, what criteria does a switch look at before
> making
> its decision?
>
> My understanding is (in order);
>
> 1. Lowest Cost to the root bridge
> 2.Lowert port address (port priority : port number) --> Is this of the
> sender
> or the receiving root bridge?
> 3.Lowest bridge ID
>
> Is my understanding correct?
>
> Also, how does a switch decide on its DESIGNATED port? Is this the lowest
> bridge ID?
>
> thanks,
>
> Jit
>
>
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Received on Sun Jun 14 2009 - 11:04:35 ART