International Business Machines Corporation

Sylvie Gohl

Alain R Blanc

Michel Poret

Bernard Brezzo

Jean-Claude Abbiate

Laurent Nicolas

Alain Saurel

Jean-Claude Robbe

Menahem Kaplan

Alain Pinzaglia

A Switch Fabric system comprising at least one Switch Fabric subsystem ( ) further including a set of Switch cores elements ( ) that are mounted in a port expansion permitting attachment of at least a first and second sets of Protocol Adapters ( ) under a routing control process. A Primary Switch controller (PSC) has a complete knowledge of the topology of the switch, e.g., the number of subsystems, the nature of the port expansion etc., while each Secondary Switch Controller only has a limited knowledge of that topology. One particular Switch Core ( ) which has a full-duplex communication capability in each Subsystem is assigned the key function to interface communication between the PSC and the other SSC in a same Switch Fabric Subsystem.

Switching fabric system having at least one subsystem including switch core elements arranged in port expansion architecture

A service message system for a switching architecture including at least one Switch Fabric ( ) comprising a switch core ( ) located in a centralized building and a set of Switch Core Access Layer (SCAL) elements distributed in different physical areas for the attachment to the different Port adapters ( ). Each SCAL elements particularly includes a SCAL receive element ( - ) and a SCAL Xmit element ( - ) for the respective access to one input port and one output port via serial links. The service message is based on the use of a Cell qualifier field at the beginning of each cell, which comprises a first and a second field. The first field is the Filtering Control field which permits an easy decoding of a service message cell, when applicable. The second field is used for determining which particular type of service message is conveyed via the cell. Following the Cell qualifier is the Switch Routing Header (SRH) which permits the characterization of the destination of the cell and is used for controlling the routing process. Preferably, the service message is used in a fault tolerance configuration where two different Switch Fabrics act as a standby to each other and shares a part of the traffic. Each one is configured as a default routing path for some ports adapters and a backup path for the others. In that particular configuration, the service message system of the invention uses the first field of the Cell qualifier to transport a Direct filtering command causing the Switch fabric to route the cell when the SRH is representative of its default output port destination. Conversely, the first field may transport a Reverse filtering command in the first field that causes the Switch fabric to reverse the default routing process. The first field is also used for characterizing a service message cell which the second field indicates the accurate type. Particularly, two types are used for the production of the filling cells when no data cell is to be transmitted at a particular location of the switching architecture.

Service message system for a switching architecture

A switching system having at least two switch fabrics. Each fabric has a switch core and a set of SCAL (Switch Core Access Layer) receive and transmit elements. The switch cores are preferably located in the same physical area but the SCALs may be distributed in different physical areas. Port Adapters distributed at different physical areas are connected to the switch fabrics via a particular SCAL element so that each switch core can receive cells from any port adapter and conversely any port adapter may receive data from either switch core. Control logic assigns a particular switch core to one port adapter for normal operations while reserving the other switch core for use when the first core is out of service. Each switch core has a mask mechanism which uses the value in a mask register to alter a bitmap value which controls the routing process. The mask registers in the two switch cores are loaded with complementary values.

Switch system comprising two switch fabrics

A fault tolerant switching architecture is provided with two separate switch fabrics each having a switch cure located in a centralized building and a set of SCAL elements distributed in different physical areas. Each SCAL element has both a SCAL receive element and a SCAL transmit element for access to a corresponding input and output port of the swatch core. A set of port adapters is distributed at different physical areas, with each connected switch fabrics via a particular SCAL element so that each switch core receives the sequence of cells coming from any port adapter and conversely any port adapter may receive cells from either one of the switch cores. Each switch fabric can detect an internal breakdown condition occurring in one of its element and send an error control signal to the peer element located in the other switch fabric. Each switch core extracts the Switch Routing Header (SRH) from the cells entering the switch core, and a routing table for obtaining a bit map value that indicates the output ports to which the cell should be routed. An additional controllable masking mechanism is used for altering the value of the bit map in response to the detection of the error control signal from the peer switch core. The routing process is then performed with the altered value of the bitmap.

Fault tolerant switching architecture

A switching system comprising a switching structure for routing cells from a set of M input ports towards a set of M output ports. The system includes a set of distributed individual Switch Core Access layer elements which communicate with one input and output port of the switching structure by means of a set of serial communication links. Each SCAL element provides attachment to at least one Protocol Adapter and comprises a set of circuits. The receive part of each circuit includes means for introducing at least one extra byte to every cell. The extra byte is reserved for carrying a routing header for controlling the switching structure in a first step, and then for use by the PINT circuit when the cell will be received by the transmit part in a second step. The transmit part of each PINT circuit comprises a control module that receives all the cells generated at the corresponding output port and controls whether to discard the cell based on the value of the extra byte.

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La Colle sur Loup, France

Sylvie Gohl