Spanning tree

[Gordon Cook]

I have a question regarding spanning tree.

I currently have a E5412zl switch configured with a number of vlans.  We also have a c7000 blade with two 6120xg switches in it.  The 6120s only have one vlan extended to them at this time.   The two switches are setup to provide redundancy with spanning tree enabled.  We would like to extend additional vlans to the blade system.  What I am not sure about is spanning tree.  I know it will check for loops again when I add the new vlans.  Will affect the current vlan.  The last time we did something that had the spanning tree reconfigure we ended up with a data problem because of the disconnection.  

I know I can do this off-line (shut down the critical servers) but would like to avoid this if possible.  

Thanks Gordon.

[Chrisd131313]

Hi Gordon,

The main thing here is what implementation of Spanning tree are you currently running? (STP/RSTP/MSTP/RPVST). If you are runnign STP or RPVST then adding additonal VLANs to teh blades is likely to give you a pause in traffic as Spaning Tree re-converges the new topology and I woudl advise that any work is done out of hours, or in an agreed maintenacne window. If you are runnign RSTP or MSTP then it is unlikely you will see a noticiable impact on the network. If you have one MSTP region then all VLANs will be a member of this and the topology will not change and the same for RSTP. It only becomes a bit more complicated if you are running RPVST as each VLAN has its own region assigned, or if you are using the legacy STP which has a very slow re-convergence time.

So based on what you have stated it is unlikely that you will have any disruption by setting up a couple of additional VLANs on your blades (as long as you runnign RSTP or MSTP).

HTH