Redundant/secondary fibre links between edge switches?

[spgsitsupport]

Have a simple network, with core being stack of Comware based 4 x 5900AF, which does the routing

Each edge cabinet (with Aruba 2920 stacks with latest firmware WB_16_10_0011) connects via single direct fibre OM4 10Gb to the core

All works fine, but as I have some spare (different route between buildings) fibre links available between cabinets, I would like to connect edge cabs between themselves for redundancy.

Last time I did that, all hell broke lose, core lost communication to almost all the cabs, even one of the Hyper-V directly connected to the core dropped off. To get it all back to working state had to drastically reboot the edge cabs & even the core!

Spanning tree is enabled on all switches, as is loop protection (per Vlan)

Core is (and was) definitely a root bridge

What else am I missing (having a blackout, sorry) to have the links between (just in case the main one goes down)

Thanks

Seb

[parnassus]

Hi Seb, how the Spanning Tree (both on Core and Edge) was exactly configured in your topology?

[spgsitsupport]

Using this:

https://community.hpe.com/t5/Comware-Based/Spanning-Tree-Problem/td-p/6175625#.YDOVyeigIuU

Procurve:

spanning-tree enable
spanning-tree mode mstp
spanning-tree force-version rstp-operation

Comware:

stp global enable
stp mode rstp
stp instance 0 root primary

stp pathcost-standard dot1t

Seb

[spgsitsupport]

Anybody?