Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1996-07-18
2001-05-22
Olms, Douglas W. (Department: 2732)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S399000
Reexamination Certificate
active
06236655
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to the field of communication systems, and more particularly to port and link identification.
BACKGROUND OF THE INVENTION
A communication system includes a collection of components that communicate, manipulate, and process information in a variety of ways. This system may support different access technologies, such as frame relay, circuit services, and new and evolving connection-based or connectionless services, that communicate information, such as data, voice, and video. Switches in the communication system employ hardware and software to route information generated by access technologies to an intended destination.
In such switches, different types of data cells are utilized to control switching connections. For example, a control cell can be used to establish communication on a connection or link. When a control cell of a particular type, such as a cell relating to an interim local management interface (ILMI), is processed at a switch control module, the switch control module (SCM) must be able to identify the port and link of origin for the control cell in order to establish communication. However, regardless of which link and processing port in a switch receives the cell of a particular type, the virtual path identification (VPI) field and the virtual channel identification (VCI) field of the control cell typically will be the same as the VPI field and VCI field, respectively, of other control cells of the same type. Thus, in some instances, the VPI/VCI identifier of a control cell cannot be used to identify a link and a port of origin for the control cell in a communication switch.
SUMMARY OF THE INVENTION
In accordance with the present invention, the disadvantages and problems associated with identifying a port and link of origin for a cell in a communication switch have been substantially reduced or eliminated.
In accordance with one embodiment of the present invention, a system is provided for identifying a processing port and a link at which a cell is received. The system includes a logical link table having a plurality of logical link entries. Each logical link entry, which corresponds to a particular link of a processing port associated with the logical link table, specifies a numerical value. The processing port may receive a cell at one of a plurality of links. The processing port can convert the cell by replacing a numerical value of an identification field, such as a virtual channel identification field, of the cell with the numerical value specified by the logical link entry corresponding to the link at which the cell is received. A switch control module, which is connected to the processing port, may receive the converted cell. The switch control module can identify the link and the processing port at which the cell corresponding to the converted cell was received by referencing a reverse mapping table using the numerical value of the logical link entry in the converted cell.
In accordance with another embodiment of the present invention, a method is provided for identifying a processing port and a link at which a cell is received. The method includes receiving a cell at one of a plurality of links of a processing port. A logical link table associated with the processing port is then referenced. The logical link table includes a plurality of logical link entries, each logical link entry corresponding to a particular link of the processing port and specifying a numerical value. The received cell is converted by replacing a numerical value of an identification field, such as a virtual channel identification field, of the cell with the numerical value specified by the logical link entry corresponding to the link at which the cell is received. The link and the processing port at which the cell was received can be identified by referencing a reverse mapping table using the numerical value specified by the logical link entry in the converted cell.
An important technical advantage of the present invention includes replacing a VCI value of a control cell with a specific logical link number corresponding to the link and port at which the control cell is received. A reverse mapping table contains information specifying which link and port are associated with each logical link number. The reverse mapping table may be accessed by the switch control module. Thus, when the switch control module processes the control cell, the switch control module is able to identify the link and port of origin for the cell using the reverse mapping table. This alleviates the need to set up a separate connection to receive control cells uniquely at each input link. A connection requires resources (queues, topology information) and is a resource to be conserved. This method allows there to be a single multipoint to point connection. Other important technical advantages are readily apparent to one skilled in the art from the following FIGURES, descriptions, and claims.
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Caldara Stephen A.
Hauser Stephen A.
Manning Thomas A.
Fujitsu Network Communications, Inc.
Olms Douglas W.
Pizarro Ricardo M.
Weingarten, Schurgin Gagnebin & Hayes LLP
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