cmEthernetTrafficPortSvcType is a read-write setting specifying whether this Ethernet port is port-based or VLAN-based. An administrator sets this to determine the port's fundamental service model, since VLAN-based (EVPL-style) service unlocks per-VLAN objects elsewhere in this table like egress VLAN trunking and ingress PVID pushing, which don't apply to a purely port-based service. For example, provisioning a single customer with dedicated use of the whole physical port would set this to port-based, while provisioning multiple distinct EVCs sharing the port by VLAN would require setting it to VLAN-based instead.