Layer 2 Extension best practices

[S891]

Hi,

We have layer 2 extension to our partners. It's a trunk link with multiple vlans. We have vlan 10,20 for which partner has the root switch configuration.  For vlan 30,40 our network has root configuration. 

What should be the best practices for this connection to give us maximum protection against any STP loop issue, other problems or any security issues.  

Thx

[Philip D'Ath]

If there is no possibility of a loop (for instance, because there is a single connection) then I would filtering out spanning tree packets on the switches, so neither side can see the other's spanning tree.