Method and apparatus for manipulating VLAN tags

摘要

An integrated multiport switch operating in a packet switched network provides the capability to alter VLAN tags on a port by port basis. An internal rules checker (IRC) analyzes the header of a data frame to determine the frame type: untagged, VLAN-tagged, or priority-tagged. The IRC searches the untagged set table for the set of ports that are untagged for a particular VLAN. The IRC passes a forwarding descriptor that includes the frame type and a operational code (opcode) to a Port Vector FIFO logic (PVF). The PVF is responsible for creating a new opcode that instructs a dequeuing logic to add, remove, modify the VLAN tag, or send the frame unmodified. The opcodes generated by the PVF are individualized for each output port.