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Hardware Design of High Speed Switch Fabric IC. Overall Architecture. Features. Supports protocol-independent switching. Data are encapsulated in switching packets across the fabric. Switching packet size is 64 bytes Supports 8x8 switch with each port up to 2.56~3.2Gbps
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Features • Supports protocol-independent switching. Data are encapsulated in switching packets across the fabric. • Switching packet size is 64 bytes • Supports 8x8 switch with each port up to 2.56~3.2Gbps • Supports scalable multichip switching
Features • 2.56~3.2Gbps I/O: --CML IO driver --Embedded SERDES --Integrated CDR
DeSerializer • Converts the CML differential input to single bit input data through input CML buffer • Converts the single bit input data at 2.56~3.2Gbps rate into 16/20 bit data bus at 160MHz clock rate • Input reference clock 160MHz • RX CML(clock multiplying unit) produces 1.28-1.6GHz clock for data recovery from external 160MHz clock
DeSerializer • Input reference clock 160MHz • CDR(Clock Data Recovery) block produces 1.28-1.6GHz clock for data recovery from external 160MHz clock and input data • Front End receiver use recovered clock to sample and de-multiplexing single input data to 4 bit data bus at 640MHz clock • Use 4 to 16/20 DEMUX to produce 16/20 bit data bus at 160MHz
DeSerializer • Comma detector to detect comma word to align data byte boundary • Use 8/10bit decoder to decode start of packet(SOP), destination port and data
8x8 TDM switch • Performs the first stage load balanced traffic redistribution after the input FIFO queue • Input to first stage switch is consecutive 64 byte packet at each input port • Outputs of first stage switch include data, data valid, destination port, and sequence ID
8x8 TDM switch • Performs the second stage Birkhoff-von-Neumann switch after the resequence and output buffer queue • Input to second stage switch is distributive data from resequence and output buffer queue • Outputs of second stage switch include data, start of packet, and destination port
8x8 TDM switch • Operates at 160MHz clock with clock period 6.2ns • For 2.56Gbps(64 bytes/packet)= 5Mpackets/s • 200ns/packet operation time(time slot)=32 cycles for 160MHz
Serializer • Performs 16/20b encoding function • Parallel to serial conversion convert 20/16 bit data bus at 160MHz to single bit output at 2.56~3.2Gbps • Differential CML output
PLL • TXPLL to generate 160MHz clock for digital core • TXPLL to generate reference 160MHz clock for synthesizing 1.28~1.6GHz clock for serializer • RXPLL to generate 1.28~1.6GHz clock for CDR from external 160MHz clock
Tasks • PLLTR--PLL(TX and RX) design and Hspice simulation • DESER--DeSerializer(CDR) design and Hspice simulation • SWH-8x8 TDM switch design, synthesis, place and route, and verification • CCODEC--Comma detect and 8/10b decoder, 8/10b encoder
Tasks • SERCML—Serializer and CML high speed IO buffer design and Hspice simulation • APRD—Analog customized layout for DERSER • APRS-- Analog customized layout for SER and driver • Full chip integration and verification • Architecture specs