Individually programmable most significant bits of VLAN ID
AssigneeBroadcom Corporation
InventorsJohnson Yen, Yi-Hsien Hao
Life of this patent
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Abstract
A network switch that includes an address resolution table and a VLAN table. The address resolution table comprises a VLAN identifier (ARL VID) in less significant bits, a MAC address, and an action code, wherein each VLAN identifier in the address resolution table is unique. The VLAN table is used for storing information related to frame forwarding. The VLAN table includes a VLAN identifier (VLAN VID) in more significant bits, a forward map and an un-tag map. The ARL VID is used to access an associated entry in the VLAN table.
Claims13
A method for forwarding an incoming frame in a network switch, the method comprising:
- upon receiving an incoming frame, converting a MAC destination address and less significant bits of a VLAN identifier (VID) from the incoming frame into a 12 bit address resolution table (ARL) address which is used to access an address resolution table;
- comparing an ARL VID and a MAC address from the address resolution table with the MAC destination address and less significant bits of the VID from the incoming frame to determine if there is an ARL hit;
- if there is an ARL hit, using an action code from the address resolution table to determine at least one egress port to which the incoming frame is sent;
- using the less significant bits of the VID of the incoming frame to access an appropriate entry in a VLAN table;
- comparing a VLAN VID from the VLAN table with more significant bits of the VID of the incoming frame, wherein if the VLAN VID is the same as the more significant bits of the VID of the incoming frame, there is a VLAN match;
- and
- forwarding the incoming frame to at least one port based on at least one of the ARL hit and the VLAN match.
An apparatus for forwarding an incoming frame in a network switch, the apparatus comprises:
- converting means for converting a MAC destination address and less significant bits of a VLAN identifier (VID) from an incoming frame into a 12 bit address resolution table (ARL) address which is used to access an address resolution table upon receiving the incoming frame;
- comparing means for comparing an ARL VID and a MAC address from the address resolution table with the MAC destination address and less significant bits of the VID from the incoming frame to determine if there is an ARL hit;
- if there is an ARE hit, means for using an action code in the address resolution table to determine at least one egress port to which the incoming frame is sent;
- means for using the less significant bits of the VID of the incoming frame to access an entry in a VLAN table;
- comparing means for comparing a VLAN VID from the VLAN table with more significant bits of the VID of the incoming frame, wherein if the VLAN VID is the same as the more significant bits of the VID of the incoming frame, there is a VLAN match;
- and
- forwarding means for forwarding the incoming frame to at least one port based on at least one of the ARL hit and the VLAN match.
Dependencies are inferred from the claim text.