MAC Controller Implementation

MAC Controller Implementation

Delta Network ASIC Division

Project Manager

Roger Lin

Content

• Project Initialization

• System Specification

• Data Flow

• ASIC Specification

• ASIC Block Diagram

• Implementation Target

• Design Flow

Content

• Interface Definition

• MAC Controller Sub-Block

• Design Phase

• Synthesis Phase

• Backend Phase

• System Engineering

Project Initialization

• Target : Ethernet Switch• Evolve from Multi-port Bridge• Kapana Network• Market v.s. Technical• Information Re-assembly

– International Showcase– DataBook– Standards

Product Hierarchic

Internet

RouterBridge

TP-HUB

Intranet

Application Trend

• Standalone Computer Process

• Database Share Localization

• Centralize Information Maintain

• Internet Access

• Remote Branch Office Handle

• E-Commerce

Multi-port Bridge

High-EndRISC CPUHigh-EndRISC CPU

MAC ControllerMAC Controller

SRAMSRAM SRAMSRAM SRAMSRAM

CAMCAMEEPROMEEPROM

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

RJ-45 BNC RJ-45 RJ-45

SerialPort

MAC ControllerMAC ControllerMAC ControllerMAC Controller MAC ControllerMAC Controller

System Specification

• Same with Multi-port Bridge– 802.3 MAC– 802.1D Bridging

• Switching Technology– Hardware Forward– Cut Through/Store and Forward– Unique Media Access

Media Access Control

• Ethernet/802.3

• Token Ring

• Token Bus

• FDDI

LLC

802.3TokenBus

TokenRing

FDDI

10B2 10B5 TP

Ethernet/802.3Transmit

Deferon ?

Start Tx

Deferon ?

Send jam

Incrementattempts

ComputeBackoff

Deferon ?

Wait backofftime

Txdone ?

Done:excessiveColError

Done:OK

Y

Y

Y

Y

Receive

Rxdone ?

FrameSmall ?(Col)

Recogaddr ?

ValidFCS ?

ValidLengh Field ?

Extra bits ?

Done:Align Error

Done:OK

Done:FCS Error

Done:Length Error

Y

Y

Y

Y

Y

Y

802.1D Bridging

• Forwarding– Outgoing Port

• Learning– Host Location

• Database– Network Topology

• Spanning Tree– solve loop

RELAY

PHY

MAC MAC

PHY

B B

Ethernet Switch System Block

Low-EndCPU

Low-EndCPU

MAC Controller

MAC Controller

SRAMSRAMEEPROMEEPROM

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

PHYChipSet

RJ-45 BNC RJ-45 RJ-45

SerialPort

MAC Controller

MAC Controller

MAC Controller

MAC Controller

MAC Controller

MAC Controller SRAMSRAMSRAMSRAMSRAMSRAMSRAMSRAM

Switching Fabric

Data Flow

• Multi-port Bridge– Concentrate on the High-End CPU– Compute and Move Data by CPU

• Ethernet Switch– Multiple Channel in Switch Fabric– Dynamic Connect by Hardware

ASIC Specification

• New MAC Controller– Major Function of CSMA/CD– Major Function of Bridging– Interface with Switch Fabric

• Switch Fabric– Crossbar– Share Bus– Share Memory

New MAC Block Diagram

802.3TransmitController

802.3TransmitController

802.3Receive

Controller

802.3Receive

Controller

Carrier Handle ControllerCarrier Handle Controller

Packet BufferWrite

Controller

Packet BufferWrite

Controller

Packet BufferRead

Controller

Packet BufferRead

Controller

Packet BufferRead

Controller

Packet BufferRead

Controller

Packet BufferWrite

Controller

Packet BufferWrite

Controller

To SwitchInterface

To SwitchInterface

From SwitchInterface

From SwitchInterface

MemoryAccess

Interface

MemoryAccess

Interface

CPU InterfaceController

CPU InterfaceController

BridgingFunction

Controller

BridgingFunction

Controller

ASIC Block Diagram

• Separate MAC Controller Module– Easy to Re-use/Replace

• Mirror Packet Buffer Controller– Reduce the Corner Case

• Separate Bridging Controller– Easy to Upgrade to Layer 3 Operation

Implementation Target

• FPGA v.s. ASIC– Low Development Cost– Short Time-to-Market– Easy to Debug– Bad Timing Budget– More Effort to Partition– Proprietary “Generic Logic Block”– Difficult to Estimate

Design FlowHDL Coding

FunctionalVerification

Synthesis

FloorPlan

Pre-SimulationStatic Timing Analysis

Layout

Post-Simulation(STA)

Easy to Maintain,Re-use and Expand

Critical pointto Success

Library Survey

First Step forLink-to-Layout

Toggle Rate for pattern driven,

STA for SynchronousDesign

802.3 Receive ControllerHighlights

• Collision Handle– Collision Drop– Late Collision to CPU

• Physical Layer Error Handle - Drop

• Runt Frame Handle - to Packet Buffer

• Long Frame Handle - to Packet Buffer

• Frame Check Sum Error Handle - Drop

802.3 Receive ControllerHighlights

• Alignment Error Handle - Drop

• Clock Synchronization

• Lose by Packet Alignment

• Wire Speed Receive

• Interface with Packet Buffer Controller

802.3 Transmit ControllerHighlights

• Collision Handle– Re-transmit Function– Skip Transmit Function

• Jam Function

• Backoff Function– [0, 2ek) where k = min (n, 10)

• Defer Function

802.3 Transmit ControllerHighlights

• Wire Speed Transmit

• Clock Synchronization

Interface Definition

Packet BufferWrite

Controller

802.3Receive

Controller

802.3Transmit

Controller

Packet BufferRead

Controller

DATA[7:0]

DATA_VALID

DATA_END

DATA_ERR

TXD[7:0]

TXS[1:0]

TXACK[1:0]

Interface Definition - RX

Network Data Payload

MII[3:0]

DATA[7:0]

DATA_VALID

DATA_END


MII[3:0]

DATA[7:0]

DATA_VALID

DATA_ERR

Interface Definition - TX


MII[3:0]

TXD[7:0]

TXS[1:0]

TXACK[1:0]

Valid Idle Valid

Valid Idle Valid

End

Idle Valid


MII[3:0]

TXD[7:0]

TXS[1:0]

TXACK[1:0]

Valid Idle Valid

Valid Idle Re/Sk

Idle

Idle

RX/TX Block Diagram

MII TXControllerMII TX

ControllerNibble to

WordNibble to

Word

Carrier Handle ControllerCarrier Handle Controller

ClockSynchronization

ClockSynchronization

FIFOFIFO

Word toByte

Word toByte

Byte toWord

Byte toWord

To PacketBuffer

Write Interface

To PacketBuffer

Write Interface

InterfaceCommandDecoder

InterfaceCommandDecoder

CRC CheckCRC Check

BackoffBackoff

DeferDefer

PhyManagement

PhyManagement

StatisticCounterStatisticCounter

Design Phase

• Clock Domain Partition– Meta Stable

• State Machine– Merely– Moore – One-hot

• Combinational– Product Term

Design Phase

• Naming Rule

• Exclusion Logic

• Datapath Sharing

• Power Consumption– FlipFlop– Gated Clock– State Bit Transition

tx_ctrl tx_ctrl (.txack(txack[1:0]),.data_shift(data_shift),.pre_end(pre_end),.vartest4(vartest4),

.txs(txs[1:0]),

.fifo_full(fifo_full),

.err(err),

.retx(retx),

.montx(montx),

.CP(CP), //load 3

.NC(NC));tx_write tx_write (

.tx_cmd_write(tx_cmd_write),

.vartest5(vartest5),

.data_shift(data_shift),

.endtag(tx_cmd_data[8]),

.full(fifo_full),

.err(err),

.CP(CP), //load 3

.NC(NC));

dffex8 DFFEx8_1( .Q(bus1[7:0]),

.QN(),

.D(txd[7:0]), .E(data_shift), .NC(NC), .CP(CP) //load 8);dffex9 DFFEx9_2( .Q(tx_cmd_data[8:0]),

.QN(),

.D({pre_end, bus1[7:0]}), .E(data_shift), .NC(NC), .CP(CP) //load 8);

assign vartest4 = {data_shift, stateQ};assign

txack[1] = (stateQ == x_start) //idle| (stateQ == x_valid) //valid| (stateQ == x_err) //idle| (stateQ == x_idle), //idle

txack[0] = (stateQ == x_start)| (stateQ == x_err) //idle| (stateQ == x_idle)| (stateQ == x_sktx),

pre_end = (txs == 2'b01) & (txack == 2'b10),data_shift = ((txs == 2'b10) | (txs == 2'b01))

& (txack == 2'b10) & (stateQ == x_valid);

always @(txs orfifo_full orerr orretx ormontx or stateQ)

beginstateD = stateQ;case (stateQ) // synopsys parallel_case

x_start :if (txs == 2'b10 & montx & ~err & ~fifo_full)

stateD = x_valid;x_valid :

if (err)stateD = x_err;

else if (txs == 2'b01)stateD = x_start;

else if (fifo_full)stateD = x_idle;

x_idle :if (~fifo_full)

stateD = x_valid;x_err :

if (retx)stateD = x_retx;

else if (~retx)stateD = x_sktx;

x_retx :stateD = x_start;

x_sktx :stateD = x_start;

default :stateD = x_start;

endcaseend

//----------------------FLIP FLOP AREA------------------always @(

posedge CP or negedge NC )

beginif (~NC)

stateQ[2:0] = #2 3'h0;else

stateQ[2:0] = #2 stateD[2:0];end//DFFC_d1 DFF0 (.Q(stateQ[0]), .D(stateD[0]), .CP(CP), .NC(NC));//DFFC_d1 DFF1 (.Q(stateQ[1]), .D(stateD[1]), .CP(CP), .NC(NC));//DFFC_d1 DFF2 (.Q(stateQ[2]), .D(stateD[2]), .CP(CP), .NC(NC));

Synthesis Phase

• Strategy– Bottom Up– Synthesis - Characterize - Re-synthesis

• Critical Path

• Fine Tune Constraint

• Register Re-timing

• Re-code RTL

Backend Phase

• Floor Plan

• ECO ( Engineering Change Order )

• Clock Skew

• Layout Density

System Engineering

• Test Environment

• Q & A

Documents

MAC Controller Implementation