System Packet Interface-4 Phase 2 (SPI-4.2) is a protocol used for data transfer between link layer and physical layer. It is an interface for packet and cell transfer between a physical (PHY) layer ...

Figure 2: Switch fabric interface comparison showing datapath and flow control widths. CSIX-L1 flow control in (c) is in-band (part of the datapath). The flow control channel for NPSI and SPI-4.2 is ...