Multiple spanning tree on 2910al-24G switches

[IShall]

Hello,

I'm trying to set up two 2910al-24G switches as SAN switches, and for SAN data have configured ports 1-23 in VLAN 2, including two ports trunked between them (ports 22,23 -> trk1).  For managment data only, I've configured a single port (24) on each switch to a third switch as an uplink port in VLAN1.

Trouble is, the trunk between the SAN switches is shut down by spanning tree on one of the switches.

I've configured on both:

spanning-tree instance 1 vlan 1

spanning-tree instance 1 24 prio 4

spanning-tree instance 2 vlan 2

spanning-tree instance 2 trk1 prio 4

I thought this would create separate, multiple independent spanning tree instances. What am I missing ?

Thanks,

[Helper]

hi,

According to your architecture description, the third switch is the root switch, then it is a normal behaviour to have the inter-switch link to this one up and working.

If you want to have the LAG working you need to modify your spanning-tree and make one of your SAN switch the root of your network.

I don't know your network, my suggestion can cause problem if your topology is more complex than the one you explain us.

Bye

[Richard Brodie_1]

Firstly, you need to ensure the two switches are in the same region. You only have multiple instance trees within the region.

spanning-tree config-name whatever

spanning tree config-revision n

Secondly, even when you have done this, you need to make one of the switches root on that instance. Pick one and:

spanning-tree instance 2 priority 4