Im reviewing the BCMSN guide, and it states that PVST (without +) can only run trunks with ISL. However on my home lab i have dot1q trunks running with pvst. Is it actually using pvst+ then?
Per VLAN Spanning Tree (PVST) wrote:
Per-VLAN Spanning Tree (PVST) maintains a spanning tree instance for each VLAN configured in the network. It uses ISL Trunking and allows a VLAN trunk to be forwarding for some VLANs while blocking for other VLANs. Since PVST treats each VLAN as a separate network, it has the ability to load balance traffic (at layer-2) by forwarding some VLANs on one trunk and other Vlans on another trunk without causing a Spanning Tree loop.
Per VLAN Spanning Tree Plus (PVST+) wrote:
Per VLAN Spanning Tree Plus (PVST+) provides the same functionality as PVST using 802.1Q trunking technology rather than ISL. PVST+ is an enhancement to the 802.1Q specification and is not supported on non-Cisco devices.
Common Spanning Tree (CST) wrote:
Common Spanning-Tree (CST) assumes one spanning-tree instance for the entire bridged network, regardless of the number of VLANs. This implementation reduces CPU load since only one Spanning Tree instance is maintained for the entire network. This implementation can be used when only one Layer 2 topology is needed in the network