Sp Switch Ports; Sp Switch Chip; Data Flow Between Switch Ports - IBM RS/6000 SP Handbook

5.2.2 SP Switch ports

An SP Switch port is part of a network device and is connected to other SP
Switch ports through the SP Switch link. The SP Switch port includes two ports
(input and output ports) for full duplex communication. The following diagram
shows the relationship between the SP Switch link and the SP Switch port.
Figure 5-2 shows the data flow between switch ports.
SP Switch Port
Figure 5-2 Data flow between switch ports

5.2.3 SP Switch chip

An SP Switch chip contains eight SP Switch ports, a central queue, and an
unbuffered crossbar, which allows packets to pass directly from receiving ports to
transmitting ports. These crossbar paths allow packets to pass through the SP
Switch (directly from the receivers to the transmitters) with low latency whenever
there is no contention for the output port. As soon as a receiver decodes the
routing information carried by an incoming packet, it asserts a crossbar request
to the appropriate transmitter. If the crossbar request is not granted, it is dropped
(and, hence, the packet will go to the central queue). Each transmitter arbitrates
SP Switch Link
Data (8 bits)
Output Port
Data Valid (1 bit)
Token (1bit)
System Clock
Data (8 bits)
Input Port
Data Valid (1 bit)
Token (1bit)
SP Switch Port
Input Port
Output Port
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Chapter 5. The Switch