stp basics

[paulow1978]

Hi there,

I wonder if someone could help me with a quick question regarding stp at work. We have a one loop network (well it is onot a loopat the moment just a line) everytime we reconnect the last fibre port to make the loop spanning tree just doesnt seem to work. I have disabled spanning tree on all 10 switches in the loop apart from on one switch where it is acting on both the fibre ports (all our switches are connected using fibre). This should work? or should I be enabling stp on at least one more switch or more?.

many thanks,

Paul

[globalnettech]

Hello Paul,

what is your excact physical setup, do you have 10 switches in a daisy-chain confgiuration, where the last switch eventually connects to both sides of the chain, and that is the one where STP is enabled ? When you say that spanning tree does not work, what are you trying to accomplish ? In your current setup, STP would indeed not block any of the two ports, since it cannot detetct a loop (that is because the other switches are not 'seen', in STP terms). If you want STP to work properly, enable it on all switches in the ring (but you still probably are going to run into trouble because of the 7 hop limit imposed by STP). You might want to consider splitting your switches, and e.g. use two of them as hub switches, and connect the other switches as hub switches. Then you could run a link between both hub switches. Just a thought...hope that makes sense.

Regards,

GNT

[paulow1978]

ahh thanks for that!,

sorry to be dumb but what do you mean by hub switches? do you mean switches that are not on the backbone loop and come off a backbone loop switch as a spur?

also we are using a mixture of backbone switchs in our config, some use stp and others use rstp (I can set the ones using rstp to use stp though) are there any other issues involved with these different versions of stp that I should know about?.

also is that a 7 hop inclusive limit?

thanks for all your help,

Paul

[paulow1978]

oh yes... in answer to your question..

we have a 6 switch daisychain config with the last switch connecting back to the first which is where stp is enabled.