I'm not considering Etherchannel or LACP.
Given 2 Ethernet switches A and B, where both switches have port 0 configured as a tagged trunk for VLAN 100 and 101 and port 1 configured as a tagged trunk for VLAN 200 and 201. Can I connect port 0 on switch A to port 0 on switch B and port 1 on switch A to port 1 on switch B without having spanning tree shut down one of the ports or otherwise cause other problems ?
Best Answer
It depends. With IEEE 802.1Q specified STP, where you have one instance per trunk, STP will block ports.
With Cisco's PVST+ (Per-VLAN STP), every VLAN has a corresponding instance of STP. This means that if there are no loops within the VLANs, STP will not block ports.
MST, defined in IEEE 802.1s, works a bit differently. Instead of providing a one-to-one VLAN-STP mapping, VLANs can be grouped together into a few instances of STP. This way, if you do STP odd-even load balancing (odd VLANs over link A, even over link B) you only need two instances of STP, instead of one instance for every single VLAN. If you use MST correctly, your proposed configuration should work without any blocked links, just like PVST+, but with VLANs grouped into instances instead of working with each VLAN independently.