switch connectivity scenario

[carl_townshend]

Hi all

If I got 2 switches, linked them together twice and put one end of the link fixed to half duplex, and the other full duplex, what implications would this have to spanning tree, could it cause a potential bridging loop?

cheers

[letsgomets]

In this scenario without utilizing port aggregation spanning tree would block forwarding on one of the links, provided you are not using port fast. If you were using portfast you would create a bridge loop and bad things will begin to happen.

If this were configured with port aggregation then they would both link up and forward but you would have data loss on the duplex mismatch link.

[carl_townshend]

if bpdu's are missed due to collisions, would stp operate correctly here though?

[letsgomets · Accepted solution]

It should. Not all bpdus will be dropped. With standard timers in place there is plenty of time for traffic to get retransmitted and learned properly. STP listens for 15 seconds. Even with dropped packets in a 15 second time frame some will get through.

[glen.grant]

Not sure why you would want to do this .  This would make the link extremely slow due to collisions and crc's errors  due the speed/duplex mismatch..