PVST question

[Mark Bowyer]

My question is, if a network does not have any redundant links, does all traffic still flow through the root bridge on each VLAN? I can see how it would if there were redundant links, but I am struggeling to picture it without.

[Edwin Summers]

If no loops exist in the topology, then no interfaces will be blocked.  Root bridge election will still occur.

But remember, even in the case where there are loops and ports blocked, all traffic does not necessarily flow through the root bridge.  Switching still occurs as it normally would.  The switches learn MAC addresses and switch packets to the appropriate port based on destination.  Depending on the topology a packet may have to travel a sub-optimal path through the root bridge to reach it's destination (due to the optimal path between source and destination being blocked), but it does not change the basic operation of switching.

Hope this helps!

[viswamin]

As long as any flavour of spanning tree is running, the root bridge selection will continue to happen.

As Edwin said, it is not necessary that all the traffic has to go via root bridge. To avoid sub optimal path taken  as Edwin pointed out, that's where the planning of root bridge come in.

with effecient planning we can minimise the sub optimal path taken by any frames.

-Vijay