Ascend Communications, Inc.

David J White

Mahesh N Ganmukhi

Prasasth R Palnati

A method and apparatus are disclosed for selectively accessing and independently sizing connection identification tables within a network switch. Upon receipt of a data unit, such as an asynchronous transfer mode cell at an input port of an Input Output Module, a plurality of selection bits are inserted into the cell header which are used to select one of a plurality of connection identifiers. The VPI/VCI addresses are mapped into a connection identifier and the connection identifier is also inserted within the respective cell header. The connection identifier may comprise an unicast connection identifier, a multicast connection identifier, or a redundant unicast identifier. The unicast, multicast and redundant identifiers are either stored in separate tables at call setup and the tables are independently selectable via use of the selection bits stored within the cell header. Alternatively, the selection bits are employed to specify a register which points to the first address for the respective type of identifiers. Thus, identifiers of a particular connection type are accessible via a base address plus an offset address. In the described manner, tables or portions of tables containing connection identifiers may be flexibly and independently sized.

Independently sizable memory pages for a plurality of connection ID

An apparatus and technique for facilitating mapping of a Multicast Circuit Identifier ('MID') to a Local Circuit Identifiers ('CID') is disclosed. Table entries for such mapping can be disposed in non-contiguous memory locations. A pointer is employed in ca h entry to indicate the location of any subsequent memory location associated with the MID. CIDs and associated memory locations are allocated only for ports that participate in a connection. To implement the apparatus and technique a first table provides an index into a second table based upon the MID. The second table includes entries having a port identification field, a pointer field and a CID field. The CID field indicates the CID associated with the port indicated by the port identification field. The CID is written to the header of the copy of the cell to be transmitted to the indicated port. The pointer indicates further entries in the second table that are associated with other copies of the cell to be transmitted in the multicast connection, if such entries exist. The CID is employed to obtain a Virtual Path Identifier ('VPI') and Virtual Circuit Identifier ('VCI') from a third table.

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Marlborough, MA, United States of America

David J White