For performance management of VLANs, we'll look at two major components:
Logical ports versus physical ports
Measuring VLAN utilization
As discussed in the VLAN overview, a logical port is a summation of all physical ports installed on a switch plus the amount of VLANs configured on all trunk ports, assuming spanning tree is active for all those VLANs. We will refer often to the logical port formula (see Equation 15-1) as reference for this section.
The ATM trunks are broken out separately in Equation 15-1. The product of the ATM trunks multiplied by the number of VLANs over that trunk needs to be doubled. The ATM trunks are the LANE ports as seen on the ATM LANE modules. ...