Package: inet.physicallayer.wired.ethernet

EthernetPlca

simple module

Implements the Ethernet Phyisical Layer Collision Avoidance (PLCA) protocol defined in the IEEE 802.3cg-2019 standard. It can be used to build an Ethernet network interface that can be connected to 10BASE-T1S multidrop links.

The PLCA protocol is implemented with the following features:

control state machine (with minor modifications)
data state machine (with some modifications)
periodic beacons to synchronize cycle start
keeping track of the current transmit opportunity
various timing parameters (beacon length, to length, etc.)
packet bursts with configurable maximum number of packets
configurable delay line to temporarily hold the frame from the MAC
carrier sense and collision signals
various end signal delimiters

The PLCA protocol is implemented with several limitations:

PHY collisions are not supported (avoidance assumed)
status state machine is not implemented (plca_status)
PLCA mode cannot be enabled/disabled dynamically (plca_en), it's always active
PLCA cannot be reset (plca_reset)
special handling of local_nodeID 255 is missing
beacons are assumed to be never lost (no invalid_beacon_timer)
data state machine cannot abort transmissions
mixed operation with CSMA/CD nodes on the same multidrop link is not supported
controller immediately starts sending a beacon
nodes start with waiting to receive a beacon

All ~EthernetPlca modules in the network interfaces on the same multidrop link must have the same plca_node_count parameter value set. Also, the local_nodeID parameter must be set to a uniqe value in the [0, plca_node_count - 1] range.

This module requires that the modules connected to it implement certain C++ interfaces. The upper layer must be connected to a module implementing the ~IEthernetCsmaMac C++ interface. One such module is the ~EthernetCsmaMac module. The lower layer must be connected to a module implementing the ~IEthernetCsmaPhy C++ interface. One such module is the ~EthernetCsmaPhy module.

Inheritance diagram

The following diagram shows inheritance relationships for this type. Unresolved types are missing from the diagram.

Extends

Name	Type	Description
SimpleModule	simple module	Base module for all INET simple modules.

Parameters

Name	Type	Default value	Description
displayStringTextFormat	string	""	Determines the text that is written on top of the submodule, supports displaying pars, watches, and module-specific information
plca_node_count	int		Maximum number of PLCA nodes on the mixing segment receiving transmit opportunities before the node with local_nodeID = 0 generates a new BEACON.
local_nodeID	int		ID representing the PLCA transmit opportunity number assigned to the node.
max_bc	int	0	Maximum number of additional packets the node is allowed to transmit in a single burst.
delay_line_length	int	100	The maximum number of nibbles that the PLCA RS variable delay line can hold.
to_timer_length	int	32b	The transmit opportunity timer should be set equal across the mixing segment for PLCA to work properly.
burst_timer_length	int	128b	This timer determines how long to wait for the MAC to send a new packet before yielding the transmit opportunity. For PLCA burst mode to work properly this timer should be set greater than one IPG.
beacon_timer_length	int	20b	Times the duration of the BEACON signal.
beacon_det_timer_length	int	22b	Timer for detecting received BEACONs.
pending_timer_length	int	512b	Defines the time the PLCA Data state diagram waits in the DELAY_PENDING state before switching to PENDING state.
commit_timer_length	int	288b	Defines the maximum time the PLCA Data state machine is allowed to stay in WAIT_MAC state.

Properties

Name	Value	Description
class	EthernetPlca
display	i=block/rxtx

Gates

Name	Direction	Size	Description
upperLayerIn	input
upperLayerOut	output
lowerLayerIn	input
lowerLayerOut	output

Signals

Name	Type	Description
dataStateChanged	long	emitted when the state of the data state machine changes, the value is one of WAIT_IDLE, IDLE, RECEIVE, HOLD, COLLIDE, DELAY_PENDING, PENDING, WAIT_MAC, TRANSMIT
packetInterval	simtime_t	emitted when a packet is sent to the PHY, the value is the time elapsed since the last packet was sent
transmitOpportunityUsed	int	emitted when a transmit opportunity starts, the value is 1 or 0
packetReceivedFromLower	inet::Packet
carrierSenseChanged	int	emitted when the incoming carrier signal changes, the value is 1 or 0
cycleLength	simtime_t	emitted when a cycle ends, the value is the duration of the cycle
rxCmd	long	emitted when the value of the rx_cmd variable changes, the value is one of NONE, BEACON, COMMIT
controlStateChanged	long	emitted when the state of the control state machine changes, the value is one of DISABLE, RESYNC, RECOVER, SEND_BEACON, SYNCING, WAIT_TO, EARLY_RECEIVE, COMMIT, YIELD, RECEIVE, TRANSMIT, BURST, ABORT, NEXT_TX_OPPORTUNITY
numPacketsPerTo	int	emitted when a transmit opportunity ends for any node, the value is the number of packets sent or received during the transmit opportunity
txCmd	long	emitted when the value of the tx_cmd variable changes, the value is one of NONE, BEACON, COMMIT
toLength	simtime_t	emitted when a transmit opportunity ends for any node, the value is the duration of the transmit opportunity
collisionChanged	int	emitted when the incoming collision signal changes, the value is 1 or 0
curID	int	emitted when the current transmit opportunity ID changes, the value is the node ID of the owner of the current transmit opportunity
numPacketsPerOwnTo	int	emitted when a transmit opportunity ends for this node, the value is the number of packets sent during the transmit opportunity
numPacketsPerCycle	int	emitted when a cycle ends, the value is the number of packets sent or received during the cycle
ownToLength	simtime_t	emitted when a transmit opportunity ends for this node, the value is the duration of the transmit opportunity
packetSentToLower	inet::Packet
packetPendingDelay	simtime_t	emitted when a packet is sent to the PHY, the value is the delay from when the packet was received from the MAC

Statistics

Name	Title	Source	Record	Unit	Interpolation Mode	Description
packetInterval	packet interval		count, histogram, vector	s	none
transmitOpportunityUsed	transmit opportunity used		count, vector		none
dataState	data state	dataStateChanged	count, vector		sample-hold	the time evolution of the state of the data state machine
cycleLength	cycle length		vector		none	the time evolution of the cycle length
rxCmd	RX command		count, vector		sample-hold
numPacketsPerTo	number of packets per transmit opportunity		vector		none	the time evolution of the number of packets sent or received per transmit opportunity for any node
txCmd	TX command		count, vector		sample-hold
controlState	control state	controlStateChanged	count, vector		sample-hold	the time evolution of the state of the control state machine
toLength	transmit opportunity length		vector		none	the time evolution of the transmit opportunity length for any node
collision	collision	collisionChanged	count, vector		sample-hold	the time evolution of the incoming collision signal
curID	current transmit opportunity ID		vector		sample-hold	the time evolution of the current transmit opportunity ID
carrierSense	carrier sense	carrierSenseChanged	count, vector		sample-hold	the time evolution of the incoming carrier sense signal
numPacketsPerOwnTo	number of packets per transmit opportunity		vector		none	the time evolution of the number of packets sent per transmit opportunity for this node
numPacketsPerCycle	number of packets per cycle		vector		none	the time evolution of the number of packets sent or received per cycle
ownToLength	own transmit opportunity length		vector		none	the time evolution of the transmit opportunity length for any node
packetPendingDelay	packet pending delay		count, histogram, vector	s	none

Source code

//
// Implements the Ethernet Phyisical Layer Collision Avoidance (PLCA)
// protocol defined in the IEEE 802.3cg-2019 standard. It can be used to build an
// Ethernet network interface that can be connected to 10BASE-T1S multidrop links.
//
// The PLCA protocol is implemented with the following features:
//  - control state machine (with minor modifications)
//  - data state machine (with some modifications)
//  - periodic beacons to synchronize cycle start
//  - keeping track of the current transmit opportunity
//  - various timing parameters (beacon length, to length, etc.)
//  - packet bursts with configurable maximum number of packets
//  - configurable delay line to temporarily hold the frame from the MAC
//  - carrier sense and collision signals
//  - various end signal delimiters
//
// The PLCA protocol is implemented with several limitations:
//  - PHY collisions are not supported (avoidance assumed)
//  - status state machine is not implemented (plca_status)
//  - PLCA mode cannot be enabled/disabled dynamically (plca_en), it's always active
//  - PLCA cannot be reset (plca_reset)
//  - special handling of local_nodeID 255 is missing
//  - beacons are assumed to be never lost (no invalid_beacon_timer)
//  - data state machine cannot abort transmissions
//  - mixed operation with CSMA/CD nodes on the same multidrop link is not supported
//  - controller immediately starts sending a beacon
//  - nodes start with waiting to receive a beacon
//
// All ~EthernetPlca modules in the network interfaces on the same multidrop link
// must have the same plca_node_count parameter value set. Also, the local_nodeID
// parameter must be set to a uniqe value in the [0, plca_node_count - 1] range.
//
// This module requires that the modules connected to it implement certain C++
// interfaces. The upper layer must be connected to a module implementing the
// ~IEthernetCsmaMac C++ interface. One such module is the ~EthernetCsmaMac module.
// The lower layer must be connected to a module implementing the ~IEthernetCsmaPhy
// C++ interface. One such module is the ~EthernetCsmaPhy module.
//
// @see ~EthernetCsmaMac, ~EthernetCsmaPhy, ~EthernetPlcaInterface
//
simple EthernetPlca extends SimpleModule like IProtocolLayer
{
    parameters:
        @class(EthernetPlca);
        // Maximum number of PLCA nodes on the mixing segment receiving transmit
        // opportunities before the node with local_nodeID = 0 generates a new
        // BEACON.
        int plca_node_count;
        // ID representing the PLCA transmit opportunity number assigned to the
        // node.
        int local_nodeID;
        // Maximum number of additional packets the node is allowed to transmit
        // in a single burst.
        int max_bc = default(0);
        // The maximum number of nibbles that the PLCA RS variable delay line
        // can hold.
        int delay_line_length = default(100);
        // The transmit opportunity timer should be set equal across the mixing
        // segment for PLCA to work properly.
        int to_timer_length @unit(b) = default(32b);
        // This timer determines how long to wait for the MAC to send a new packet
        // before yielding the transmit opportunity. For PLCA burst mode to work
        // properly this timer should be set greater than one IPG.
        int burst_timer_length @unit(b) = default(128b);
        // Times the duration of the BEACON signal.
        int beacon_timer_length @unit(b) = default(20b);
        // Timer for detecting received BEACONs.
        int beacon_det_timer_length @unit(b) = default(22b);
        // Defines the time the PLCA Data state diagram waits in the DELAY_PENDING
        // state before switching to PENDING state.
        int pending_timer_length @unit(b) = default(512b);
        // Defines the maximum time the PLCA Data state machine is allowed to stay
        // in WAIT_MAC state.
        int commit_timer_length @unit(b) = default(288b);
        // emitted when the current transmit opportunity ID changes, the value
        // is the node ID of the owner of the current transmit opportunity
        @signal[curID](type=int);
        // emitted when the incoming carrier signal changes, the value is 1 or 0
        @signal[carrierSenseChanged](type=int);
        // emitted when the incoming collision signal changes, the value is 1 or 0
        @signal[collisionChanged](type=int);
        // emitted when the state of the control state machine changes, the value is one of DISABLE, RESYNC, RECOVER, SEND_BEACON, SYNCING, WAIT_TO, EARLY_RECEIVE, COMMIT, YIELD, RECEIVE, TRANSMIT, BURST, ABORT, NEXT_TX_OPPORTUNITY
        @signal[controlStateChanged](type=long);
        // emitted when the state of the data state machine changes, the value is one of WAIT_IDLE, IDLE, RECEIVE, HOLD, COLLIDE, DELAY_PENDING, PENDING, WAIT_MAC, TRANSMIT 
        @signal[dataStateChanged](type=long);
        // emitted when the value of the rx_cmd variable changes, the value is one of NONE, BEACON, COMMIT
        @signal[rxCmd](type=long);
        // emitted when the value of the tx_cmd variable changes, the value is one of NONE, BEACON, COMMIT
        @signal[txCmd](type=long);
        // emitted when a packet is sent to the PHY, the value is the delay from when the packet was received from the MAC
        @signal[packetPendingDelay](type=simtime_t);
        // emitted when a packet is sent to the PHY, the value is the time elapsed since the last packet was sent
        @signal[packetInterval](type=simtime_t);
        // emitted when a transmit opportunity starts, the value is 1 or 0
        @signal[transmitOpportunityUsed](type=int);
        // emitted when a transmit opportunity ends for any node, the value is the number of packets sent or received during the transmit opportunity
        @signal[numPacketsPerTo](type=int);
        // emitted when a transmit opportunity ends for this node, the value is the number of packets sent during the transmit opportunity
        @signal[numPacketsPerOwnTo](type=int);
        // emitted when a cycle ends, the value is the number of packets sent or received during the cycle
        @signal[numPacketsPerCycle](type=int);
        // emitted when a transmit opportunity ends for any node, the value is the duration of the transmit opportunity
        @signal[toLength](type=simtime_t);
        // emitted when a transmit opportunity ends for this node, the value is the duration of the transmit opportunity
        @signal[ownToLength](type=simtime_t);
        // emitted when a cycle ends, the value is the duration of the cycle
        @signal[cycleLength](type=simtime_t);
        @signal[packetSentToLower](type=inet::Packet);
        @signal[packetReceivedFromLower](type=inet::Packet);
        // the time evolution of the current transmit opportunity ID
        @statistic[curID](title="current transmit opportunity ID"; record=vector; interpolationmode=sample-hold);
        // the time evolution of the incoming carrier sense signal
        @statistic[carrierSense](title="carrier sense"; type=int; source=carrierSenseChanged; record=count,vector; interpolationmode=sample-hold);
        // the time evolution of the incoming collision signal
        @statistic[collision](title="collision"; type=int; source=collisionChanged; record=count,vector; interpolationmode=sample-hold);
        // the time evolution of the state of the control state machine
        @statistic[controlState](title="control state"; type=enum; enum=DISABLE,RESYNC,RECOVER,SEND_BEACON,SYNCING,WAIT_TO,EARLY_RECEIVE,COMMIT,YIELD,RECEIVE,TRANSMIT,BURST,ABORT,NEXT_TX_OPPORTUNITY; source=controlStateChanged; record=count,vector; interpolationmode=sample-hold);
        // the time evolution of the state of the data state machine
        @statistic[dataState](title="data state"; type=enum; enum=WAIT_IDLE,IDLE,RECEIVE,HOLD,COLLIDE,DELAY_PENDING,PENDING,WAIT_MAC,TRANSMIT; source=dataStateChanged; record=count,vector; interpolationmode=sample-hold);
        @statistic[rxCmd](title="RX command"; type=enum; enum=NONE,BEACON,COMMIT; record=count,vector; interpolationmode=sample-hold);
        @statistic[txCmd](title="TX command"; type=enum; enum=NONE,BEACON,COMMIT; record=count,vector; interpolationmode=sample-hold);
        @statistic[packetPendingDelay](title="packet pending delay"; unit=s; record=count,histogram,vector; interpolationmode=none);
        @statistic[packetInterval](title="packet interval"; unit=s; record=count,histogram,vector; interpolationmode=none);
        @statistic[transmitOpportunityUsed](title="transmit opportunity used"; record=count,vector; interpolationmode=none);
        // the time evolution of the number of packets sent or received per transmit opportunity for any node
        @statistic[numPacketsPerTo](title="number of packets per transmit opportunity"; record=vector; interpolationmode=none);
        // the time evolution of the number of packets sent per transmit opportunity for this node
        @statistic[numPacketsPerOwnTo](title="number of packets per transmit opportunity"; record=vector; interpolationmode=none);
        // the time evolution of the number of packets sent or received per cycle
        @statistic[numPacketsPerCycle](title="number of packets per cycle"; record=vector; interpolationmode=none);
        // the time evolution of the transmit opportunity length for any node
        @statistic[toLength](title="transmit opportunity length"; record=vector; interpolationmode=none);
        // the time evolution of the transmit opportunity length for any node
        @statistic[ownToLength](title="own transmit opportunity length"; record=vector; interpolationmode=none);
        // the time evolution of the cycle length
        @statistic[cycleLength](title="cycle length"; record=vector; interpolationmode=none);
        @display("i=block/rxtx");
    gates:
        input upperLayerIn @labels(EtherFrame);
        output upperLayerOut @labels(EtherFrame);
        input lowerLayerIn @labels(EtherFrame);
        output lowerLayerOut @labels(EtherFrame);
}

File: src/inet/physicallayer/wired/ethernet/EthernetPlca.ned