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-   -   switches, spanning tree question regarding designated ports and switches ( 12-18-2008 11:42 AM

switches, spanning tree question regarding designated ports and switches
As far as i understand STP, every switch has one RP with the lowest
path cost back to the root switch. If a segment exists with multiple
switches attached to it, as in the case of redundancy, am i correct in

1. there is only 1 switch which is designated switch and has 1
designated port upon which it forwards frames as it is explained in
the books
2. what does the other switch do ? block everything ?

I think 1 switch allows everything and the other switch blocks
everything except for 1 Designated port which it uses for what exactly

I'm a bit lost here, i understand until the RP concept, after that i'm
slightly confused.

Can anyone put me back on track here?
Much appreciated. Also a link to STP loops explained would be welcome,
i only see documents with bridge loops explained, but as these are
transparent, i think they work slighly different then a modern switch?

Kind regards,

donjohnston 12-30-2008 01:24 AM

1) Another way (the way I prefer) of expressing it is: On any segment, there is only one designated port. All other ports are either root or non-designated (blocking)

2) See #1 :)

The thing with bridges and switches is that they're basically the same. That's why we use term like "root bridge" and "bridge ID"

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