Automatic filtering and creation of virtual lans among a plurality of switch ports

Abstract

In a method and apparatus for performing multiprotocol switching and routing, incoming data packets are examined and the flow (i.e., source and destination) with which they are associated is determined. A flow table contains forwarding information that can be applied to all the packets belonging to the flow. If an entry is not present in the table for the particular flow, the packet is forwarded to the CPU to be processed. The CPU can then update the table with new forwarding information to be applied to all future packets of the same flow. When the forwarding information is already present in the table, packets can be forwarded at wire-speed. A dedicated ASIC is preferably employed to contain the table, as well as the engine for examining the packets and forwarding them according to the stored information. Decision-making tasks are thus more efficiently partitioned between the switch and the CPU so as to minimize processing overhead. Processes executing on the CPU maintain information regarding filters, mirrors, priorities, and VLANs. Such information is further integrated with the flow table forwarding information when flows corresponding to the established filters, mirrors, priorities and VLANs are detected. Accordingly, filters, mirrors, priorities and VLANs can be automatically implemented when forwarding decisions are made, which implementation is done at wire speeds. According to another aspect, VLANs are automatically created and updated based on the automatic detection of multicast groups existing among the hosts connected to the ports of the switch. After such VLANs are established, broadcast packets destined for the detected multicast groups are forwarded only along ports whose hosts are members thereof, thereby preventing needless and burdensome traffic from congesting other network segments and host connection.