Method and apparatus for controlling data flow within a switching device

Abstract

A method and apparatus for controlling data flow within a switching device are provided. The switching device includes a cell-switched backplane. Both packet switched and cell switched network interface cards may be coupled to the cell-switched backplane. A destination tag is created for each unique destination port and for each unique set of destination ports. The destination tags are used to index a master destination tag table. The entry of the master destination tag table that corresponds to a given destination tag includes a destination mask that indicates which ports are destination ports the given destination tag. Local tables are built and maintained within each network interface card based on the information contained in the master destination tag table. When a network interface receives data from an external device, the network interface determines the destination tag associated with the data. Once the destination tag is determined, it is used as an index to the locally stored tables to determine whether the data should be forwarded to any local ports, and whether the data should be sent over the cell-switched backplane to other network interfaces within the switching device. When a network interface receives data over the backplane, the network interface uses the destination tag as an index to a locally stored table to determine to which local ports the data should be sent. Tables also establish correlations between destination tags and control information for converting data between packets and cells.