Backbone forwarding scheme for multiport network switch

A network switching system comprising

• multiple ports including at least one backbone port for providing data communications with backbone network nodes, and
• a decision making engine responsive to a received data packet to control forwarding the received data packet to a transmit port,
• the decision making engine including a destination address logic circuit for comparing destination information of the received data packet with a predetermined set of address data,
• the decision making engine being configured for forwarding the received data packet to the at least one backbone port if the destination information of the received data packet is not found in the predetermined set of address data,
• wherein the multiple ports include backbone ports for multiple VLANs supported by the system.

In a network switch having a plurality of ports including at least one backbone port for providing data communications with backbone network nodes, a method of data forwarding comprising the steps of:

• comparing destination information of a received data packet with a predetermined set of address data, and
• forwarding the received data packet to the at least one backbone port if the destination information of the received data packet is not found in the predetermined set of address data;
• the method further comprising comparing source address information of the received data packet with the predetermined set of address data,
• wherein in a regular mode of operation, address information of the received data packet is added to the predetermined set of address data if the source address information of the received data packet is not found in the predetermined set of address data, and
• in a backbone mode of operation, the address information of a data packet received from the at least one backbone port is prevented from being added to the predetermined set of address data.

In a network switch having a plurality of ports including at least one backbone port for providing data communications with backbone network nodes, a method of data forwarding comprising the steps of:

• comparing destination information of a received data packet with a predetermined set of address data, and
• forwarding the received data packet to the at least one backbone port if the destination information of the received data packet is not found in the predetermined set of address data,
• wherein a first data packet received from a first VLAN is forwarded to at least one first backbone port for the first VLAN if the destination information of the first received data packet is not found in the predetermined set of address data, and
• a second data packet received from a second VLAN is forwarded to at least one second backbone port for the second VLAN if the destination information of the second received data packet is not found in the predetermined set of address data.