Each valid LAN VCC is either Main or Sub. This parameter is configured only once on creation of a LAN VCC. It can not be changed after creation. In order to change the Mode, user should delete the connection and create a new one. main - A LAN VCC, which holds its own bridge port. Bridge forwarding and Bridge learning is performed only on Main VCCs. For working on a transparent bridge, that doesn't perform layer 2 priority mapping, a Main VCC should be opened, which is the default connection Mode. When working with layer 2 priority, a group of LAN VCCs should be configured, where each group will be associated with only one Main VCC. A specific Main can not be used by more than one group. sub - A LAN VCC is not part of the bridging mechanism. A Sub VCC automatically inherit some general definitions from Main VCC of its group: ATM Slot/Port and LAN Slot/Port. Max number of Sub VCCs allowed per group is: [Number of Priorities - 1].