A Device for a Csma Network Link. More...

#include <csma-net-device.h>

Inheritance diagram for ns3::CsmaNetDevice:

Collaboration diagram for ns3::CsmaNetDevice:

Public Types
enum	CsmaEncapsulationMode { ETHERNET_V1, IP_ARP, RAW, LLC }
Public Member Functions
	CsmaNetDevice ()
virtual	~CsmaNetDevice ()
void	SetInterframeGap (Time t)
void	SetBackoffParams (Time slotTime, uint32_t minSlots, uint32_t maxSlots, uint32_t maxRetries, uint32_t ceiling)
bool	Attach (Ptr< CsmaChannel > ch)
void	SetQueue (Ptr< Queue > queue)
void	SetReceiveErrorModel (Ptr< ErrorModel > em)
void	Receive (Ptr< Packet > p)
bool	IsSendEnabled (void)
void	SetSendEnable (bool enable)
bool	IsReceiveEnabled (void)
void	SetReceiveEnable (bool enable)
void	SetAddress (Mac48Address addr)
virtual void	SetName (const std::string name)
virtual std::string	GetName (void) const
virtual void	SetIfIndex (const uint32_t index)
virtual uint32_t	GetIfIndex (void) const
virtual Ptr< Channel >	GetChannel (void) const
virtual Address	GetAddress (void) const
virtual bool	SetMtu (const uint16_t mtu)
virtual uint16_t	GetMtu (void) const
virtual bool	IsLinkUp (void) const
virtual void	SetLinkChangeCallback (Callback< void > callback)
virtual bool	IsBroadcast (void) const
virtual Address	GetBroadcast (void) const
virtual bool	IsMulticast (void) const
virtual Address	GetMulticast (void) const
	Return the MAC multicast base address used when mapping multicast groups to MAC multicast addresses.
virtual Address	MakeMulticastAddress (Ipv4Address multicastGroup) const
	Make and return a MAC multicast address using the provided multicast group.
virtual bool	IsPointToPoint (void) const
virtual bool	Send (Ptr< Packet > packet, const Address &dest, uint16_t protocolNumber)
virtual Ptr< Node >	GetNode (void) const
virtual void	SetNode (Ptr< Node > node)
virtual bool	NeedsArp (void) const
virtual void	SetReceiveCallback (NetDevice::ReceiveCallback cb)
Static Public Member Functions
static TypeId	GetTypeId (void)
	This method returns the TypeId associated to ns3::CsmaNetDevice.
Protected Member Functions
virtual void	DoDispose (void)
Ptr< Queue >	GetQueue (void) const
void	AddHeader (Ptr< Packet > p, Mac48Address dest, uint16_t protocolNumber)
bool	ProcessHeader (Ptr< Packet > p, uint16_t &param)
Private Types
enum	TxMachineState { READY, BUSY, GAP, BACKOFF }
Private Member Functions
CsmaNetDevice &	operator= (const CsmaNetDevice &o)
	CsmaNetDevice (const CsmaNetDevice &o)
void	Init (bool sendEnable, bool receiveEnable)
void	TransmitStart ()
void	TransmitCompleteEvent (void)
void	TransmitReadyEvent (void)
void	TransmitAbort (void)
void	NotifyLinkUp (void)
Private Attributes
uint32_t	m_deviceId
bool	m_sendEnable
bool	m_receiveEnable
TxMachineState	m_txMachineState
CsmaEncapsulationMode	m_encapMode
DataRate	m_bps
Time	m_tInterframeGap
Backoff	m_backoff
Ptr< Packet >	m_currentPkt
Ptr< CsmaChannel >	m_channel
Ptr< Queue >	m_queue
Ptr< ErrorModel >	m_receiveErrorModel
TracedCallback< Ptr< const Packet > >	m_rxTrace
TracedCallback< Ptr< const Packet > >	m_dropTrace
Ptr< Node >	m_node
Mac48Address	m_address
NetDevice::ReceiveCallback	m_rxCallback
uint32_t	m_ifIndex
std::string	m_name
bool	m_linkUp
Callback< void >	m_linkChangeCallback
uint16_t	m_mtu

Detailed Description

A Device for a Csma Network Link.

The Csma net device class is analogous to layer 1 and 2 of the TCP stack. The NetDevice takes a raw packet of bytes and creates a protocol specific packet from them.

The Csma net device class takes a packet and adds (or removes) the headers/trailers that are associated with EthernetV1, EthernetV2, RAW or LLC protocols. The EthernetV1 packet type adds and removes Ethernet destination and source addresses. The LLC packet type adds and removes LLC snap headers. The raw packet type does not add or remove any headers.

Each Csma net device will receive all packets written to the Csma link. The ProcessHeader function can be used to filter out the packets such that higher level layers only receive packets that are addressed to their associated net devices

Member Enumeration Documentation

enum ns3::CsmaNetDevice::CsmaEncapsulationMode

Enumeration of the types of packets supported in the class.

Enumerator:

ETHERNET_V1	Version one ethernet packet, length field
IP_ARP	Ethernet packet encapsulates IP/ARP packet
RAW	Packet that contains no headers
LLC	LLC packet encapsulation

enum ns3::CsmaNetDevice::TxMachineState [private]

Enumeration of the states of the transmit machine of the net device.

Enumerator:

READY	The transmitter is ready to begin transmission of a packet
BUSY	The transmitter is busy transmitting a packet
GAP	The transmitter is in the interframe gap time
BACKOFF	The transmitter is waiting for the channel to be free

Constructor & Destructor Documentation

ns3::CsmaNetDevice::CsmaNetDevice ( )

Construct a CsmaNetDevice

This is the default constructor for a CsmaNetDevice.

virtual ns3::CsmaNetDevice::~CsmaNetDevice ( ) [virtual]

Destroy a CsmaNetDevice

This is the destructor for a CsmaNetDevice.

ns3::CsmaNetDevice::CsmaNetDevice ( const CsmaNetDevice & o ) [private]

Copy constructor is declared but not implemented. This disables the copy constructor for CsmaNetDevice objects.

Member Function Documentation

void ns3::CsmaNetDevice::AddHeader	(	Ptr< Packet >	p,
		Mac48Address	dest,
		uint16_t	protocolNumber
	)			`[protected]`

Adds the necessary headers and trailers to a packet of data in order to respect the packet type

Parameters:

	p	Packet to which header should be added
	dest	MAC destination address to which packet should be sent
	protocolNumber	In some protocols, identifies the type of payload contained in this packet.

bool ns3::CsmaNetDevice::Attach ( Ptr< CsmaChannel > ch )

Attach the device to a channel.

The function Attach is used to add a CsmaNetDevice to a CsmaChannel.

See also:: SetDataRate (); SetInterframeGap ()

Parameters:

ch

a pointer to the channel to which this object is being attached.

virtual void ns3::CsmaNetDevice::DoDispose ( void ) [protected, virtual]

Perform any object release functionality required to break reference cycles in reference counted objects held by the device.

Reimplemented from ns3::Object.

virtual Address ns3::CsmaNetDevice::GetAddress ( void ) const [virtual]

Returns:: the current Address of this interface.

Implements ns3::NetDevice.

virtual Address ns3::CsmaNetDevice::GetBroadcast ( void ) const [virtual]

Returns:: the broadcast address supported by this netdevice.

Calling this method is invalid if IsBroadcast returns not true.

Implements ns3::NetDevice.

virtual Ptr<Channel> ns3::CsmaNetDevice::GetChannel ( void ) const [virtual]

Returns:: the channel this NetDevice is connected to. The value returned can be zero if the NetDevice is not yet connected to any channel.

Implements ns3::NetDevice.

virtual uint32_t ns3::CsmaNetDevice::GetIfIndex ( void ) const [virtual]

Returns:: index ifIndex of the device

Implements ns3::NetDevice.

virtual uint16_t ns3::CsmaNetDevice::GetMtu ( void ) const [virtual]

Returns:: the link-level MTU in bytes for this interface.

This value is typically used by the IP layer to perform IP fragmentation when needed.

Implements ns3::NetDevice.

virtual Address ns3::CsmaNetDevice::GetMulticast ( void ) const [virtual]

Return the MAC multicast base address used when mapping multicast groups to MAC multicast addresses.

Typically when one constructs a multicast MAC addresses, some bits from the IP multicast group are copied into a corresponding MAC multicast group. In EUI-48, for example, the low order 23 bits of the multicast group are copied to the MAC multicast group base address.

This method allows access to the underlying MAC multicast group base address. It is expected that in most cases, a net device client will allow the net device to perform the actual construction of the multicast address. Use of this method is discouraged unless you have a good reason to perform a custom mapping. You should prefer NetDevice::MakeMulticastAddress which will do the RFC-specified mapping for the net device in question.

Returns:: The multicast address supported by this net device.

Warning:: Calling this method is invalid if IsMulticast returns not true. The method NS_ASSERTs if the device is not a multicast device.

See also:: NetDevice::MakeMulticastAddress

Implements ns3::NetDevice.

virtual std::string ns3::CsmaNetDevice::GetName ( void ) const [virtual]

Returns:: name name of the device (e.g. "eth0")

Implements ns3::NetDevice.

virtual Ptr<Node> ns3::CsmaNetDevice::GetNode ( void ) const [virtual]

Get the node to which this device is attached.

Returns:: Ptr to the Node to which the device is attached.

Implements ns3::NetDevice.

Ptr<Queue> ns3::CsmaNetDevice::GetQueue ( void ) const [protected]

Get a copy of the attached Queue.

This method is provided for any derived class that may need to get direct access to the underlying queue.

Returns:: a pointer to the queue.

static TypeId ns3::CsmaNetDevice::GetTypeId ( void ) [static]

This method returns the TypeId associated to ns3::CsmaNetDevice.

This object is accessible through the following paths with Config::Set and Config::Connect:

/NodeList/[i]/DeviceList/[i]/$ns3CsmaNetDevice

Attributes defined for this type:

Address: The address of this device.
- Set with class: Mac48AddressValue
- Underlying type: Mac48Address
- Initial value: ff:ff:ff:ff:ff:ff
- Flags: construct write read
EncapsulationMode: The link-layer encapsulation type to use.
- Set with class: ns3::EnumValue
- Underlying type: EthernetV1|IpArp|Raw|Llc
- Initial value: Llc
- Flags: construct write read
SendEnable: Enable or disable the transmitter section of the device.
- Set with class: BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: construct write read
ReceiveEnable: Enable or disable the receiver section of the device.
- Set with class: BooleanValue
- Underlying type: bool
- Initial value: true
- Flags: construct write read
RxErrorModel: The receiver error model used to simulate packet loss
- Set with class: ns3::PointerValue
- Underlying type: ns3::Ptr< ns3::ErrorModel >
- Initial value: 0
- Flags: construct write read
TxQueue: A queue to use as the transmit queue in the device.
- Set with class: ns3::PointerValue
- Underlying type: ns3::Ptr< ns3::Queue >
- Initial value: 0
- Flags: construct write read

TraceSources defined for this type:

Rx: Trace source to fire on reception of a MAC packet.
Drop: Trace source to fire on when a MAC packet is dropped.

Reimplemented from ns3::NetDevice.

void ns3::CsmaNetDevice::Init	(	bool	sendEnable,
		bool	receiveEnable
	)			`[private]`

Initialization function used during object construction.

virtual bool ns3::CsmaNetDevice::IsBroadcast ( void ) const [virtual]

Returns:: true if this interface supports a broadcast address, false otherwise.

Implements ns3::NetDevice.

virtual bool ns3::CsmaNetDevice::IsLinkUp ( void ) const [virtual]

Returns:: true if link is up; false otherwise

Implements ns3::NetDevice.

virtual bool ns3::CsmaNetDevice::IsMulticast ( void ) const [virtual]

Returns:: value of m_isMulticast flag

Implements ns3::NetDevice.

virtual bool ns3::CsmaNetDevice::IsPointToPoint ( void ) const [virtual]

Is this a point to point link?

Returns:: false.

Implements ns3::NetDevice.

bool ns3::CsmaNetDevice::IsReceiveEnabled ( void )

Is the receive side of the network device enabled?

Returns:: True if the receiver side is enabled, otherwise false.

bool ns3::CsmaNetDevice::IsSendEnabled ( void )

Is the send side of the network device enabled?

Returns:: True if the send side is enabled, otherwise false.

virtual Address ns3::CsmaNetDevice::MakeMulticastAddress ( Ipv4Address multicastGroup ) const [virtual]

Make and return a MAC multicast address using the provided multicast group.

RFC 1112 says that an Ipv4 host group address is mapped to an Ethernet multicast address by placing the low-order 23-bits of the IP address into the low-order 23 bits of the Ethernet multicast address 01-00-5E-00-00-00 (hex).

This method performs the multicast address creation function appropriate to an EUI-48-based CSMA device. This MAC address is encapsulated in an abstract Address to avoid dependencies on the exact address format.

Parameters:

multicastGroup

The IP address for the multicast group destination of the packet.

Returns:: The MAC multicast Address used to send packets to the provided multicast group.

See also:: Ipv4Address; Mac48Address; Address

Implements ns3::NetDevice.

virtual bool ns3::CsmaNetDevice::NeedsArp ( void ) const [virtual]

Does this device need to use the address resolution protocol?

Returns:: True if the encapsulation mode is set to a value that requires ARP (IP_ARP or LLC).

Implements ns3::NetDevice.

void ns3::CsmaNetDevice::NotifyLinkUp ( void ) [private]

Notify any interested parties that the link has come up.

CsmaNetDevice& ns3::CsmaNetDevice::operator= ( const CsmaNetDevice & o ) [private]

Operator = is declared but not implemented. This disables the assigment operator for CsmaNetDevice objects.

bool ns3::CsmaNetDevice::ProcessHeader	(	Ptr< Packet >	p,
		uint16_t &	param
	)			`[protected]`

Removes, from a packet of data, all headers and trailers that relate to the packet type

Parameters:

	p	Packet whose headers need to be processed
	param	An integer parameter that can be set by the function to return information gathered in the header

Returns:: Returns true if the packet should be forwarded up the protocol stack.

void ns3::CsmaNetDevice::Receive ( Ptr< Packet > p )

Receive a packet from a connected CsmaChannel.

The CsmaNetDevice receives packets from its connected channel and forwards them up the protocol stack. This is the public method used by the channel to indicate that the last bit of a packet has arrived at the device.

See also:: CsmaChannel

Parameters:

p

a reference to the received packet

virtual bool ns3::CsmaNetDevice::Send	(	Ptr< Packet >	packet,
		const Address &	dest,
		uint16_t	protocolNumber
	)			`[virtual]`

Start sending a packet down the channel.

Implements ns3::NetDevice.

void ns3::CsmaNetDevice::SetAddress ( Mac48Address addr )

Set the MAC address of the the network device.

Parameters:

addr

The Mac48Address to use as the address of the device.

void ns3::CsmaNetDevice::SetBackoffParams	(	Time	slotTime,
		uint32_t	minSlots,
		uint32_t	maxSlots,
		uint32_t	maxRetries,
		uint32_t	ceiling
	)

Set the backoff parameters used to determine the wait to retry transmitting a packet when the channel is busy.

See also:: Attach ()

Parameters:

	slotTime	Length of a packet slot (or average packet time)
	minSlots	Minimum number of slots to wait
	maxSlots	Maximum number of slots to wait
	maxRetries	Maximum number of retries before packet is discard
	ceiling	Cap on the exponential function when calculating max slots

virtual void ns3::CsmaNetDevice::SetIfIndex ( const uint32_t index ) [virtual]

Parameters:

index

ifIndex of the device

Implements ns3::NetDevice.

void ns3::CsmaNetDevice::SetInterframeGap ( Time t )

Set the inteframe gap used to separate packets. The interframe gap defines the minimum space required between packets sent by this device. As in Ethernet, it defaults to 96 bit times.

Parameters:

t

the interframe gap time

virtual void ns3::CsmaNetDevice::SetLinkChangeCallback ( Callback< void > callback ) [virtual]

Parameters:

callback

the callback to invoke

Register a callback invoked whenever the link status changes to UP. This callback is typically used by the IP/ARP layer to flush the ARP cache whenever the link goes up.

Implements ns3::NetDevice.

virtual bool ns3::CsmaNetDevice::SetMtu ( const uint16_t mtu ) [virtual]

Parameters:

mtu

MTU value, in bytes, to set for the device

Returns:: whether the MTU value was within legal bounds

Override for default MTU defined on a per-type basis.

Implements ns3::NetDevice.

virtual void ns3::CsmaNetDevice::SetName ( const std::string name ) [virtual]

Parameters:

name

name of the device (e.g. "eth0")

Implements ns3::NetDevice.

virtual void ns3::CsmaNetDevice::SetNode ( Ptr< Node > node ) [virtual]

Set the node to which this device is being attached.

Parameters:

node

Ptr to the Node to which the device is being attached.

Implements ns3::NetDevice.

void ns3::CsmaNetDevice::SetQueue ( Ptr< Queue > queue )

Attach a queue to the CsmaNetDevice.

The CsmaNetDevice "owns" a queue. This queue may be set by higher level topology objects to implement a particular queueing method such as DropTail or RED.

See also:: Queue; DropTailQueue

Parameters:

queue

a Ptr to the queue for being assigned to the device.

virtual void ns3::CsmaNetDevice::SetReceiveCallback ( NetDevice::ReceiveCallback cb ) [virtual]

Set the callback to be used to notify higher layers when a packet has been received.

Parameters:

cb

The callback.

Implements ns3::NetDevice.

void ns3::CsmaNetDevice::SetReceiveEnable ( bool enable )

Enable or disable the receive side of the network device.

Parameters:

enable

Enable the receive side if true, otherwise disable.

void ns3::CsmaNetDevice::SetReceiveErrorModel ( Ptr< ErrorModel > em )

Attach a receive ErrorModel to the CsmaNetDevice.

The CsmaNetDevice may optionally include an ErrorModel in the packet receive chain to simulate data errors in during transmission.

See also:: ErrorModel

Parameters:

em

a pointer to the ErrorModel

void ns3::CsmaNetDevice::SetSendEnable ( bool enable )

Enable or disable the send side of the network device.

Parameters:

enable

Enable the send side if true, otherwise disable.

void ns3::CsmaNetDevice::TransmitAbort ( void ) [private]

Aborts the transmission of the current packet

If the net device has tried to transmit a packet for more times than the maximum allowed number of retries (channel always busy) then the packet is dropped.

void ns3::CsmaNetDevice::TransmitCompleteEvent ( void ) [private]

Stop Sending a Packet Down the Wire and Begin the Interframe Gap.

The TransmitCompleteEvent method is used internally to finish the process of sending a packet out on the channel. During execution of this method the TransmitEnd method is called on the channel to let it know that the physical device this class represents has finished sending simulated signals. The channel uses this event to begin its speed of light delay timer after which it notifies the Net Device(s) at the other end of the link that new bits have arrived (it delivers the Packet). During this method, the net device also schedules the TransmitReadyEvent at which time the transmitter becomes ready to send the next packet.

See also:: CsmaChannel::TransmitEnd (); TransmitReadyEvent ()

void ns3::CsmaNetDevice::TransmitReadyEvent ( void ) [private]

Cause the Transmitter to Become Ready to Send Another Packet.

The TransmitReadyEvent method is used internally to re-enable the transmit machine of the net device. It is scheduled after a suitable interframe gap after the completion of the previous transmission. The queue is checked at this time, and if there is a packet waiting on the queue, the transmission process is begun.

If a packet is in the queue, it is extracted for the queue as the next packet to be transmitted by the net device.

See also:: TransmitStart ()

void ns3::CsmaNetDevice::TransmitStart ( ) [private]

Start Sending a Packet Down the Wire.

The TransmitStart method is the method that is used internally in the CsmaNetDevice to begin the process of sending a packet out on the channel. A corresponding method is called on the channel to let it know that the physical device this class represents has actually started sending signals, this causes the channel to enter the BUSY state. An event is scheduled for the time at which the bits have been completely transmitted.

If the channel is found to be BUSY, this method reschedules itself for execution at a later time (within the backoff period).

See also:: CsmaChannel::TransmitStart (); TransmitCompleteEvent ()

Member Data Documentation

Mac48Address ns3::CsmaNetDevice::m_address [private]

The MAC address which has been assigned to this device.

Backoff ns3::CsmaNetDevice::m_backoff [private]

Holds the backoff parameters and is used to calculate the next backoff time to use when the channel is busy and the net device is ready to transmit

DataRate ns3::CsmaNetDevice::m_bps [private]

The data rate that the Net Device uses to simulate packet transmission timing.

See also:: class DataRate

Ptr<CsmaChannel> ns3::CsmaNetDevice::m_channel [private]

The CsmaChannel to which this CsmaNetDevice has been attached.

See also:: class CsmaChannel

Ptr<Packet> ns3::CsmaNetDevice::m_currentPkt [private]

Next packet that will be transmitted (if transmitter is not currently transmitting) or packet that is currently being transmitted.

uint32_t ns3::CsmaNetDevice::m_deviceId [private]

Device ID returned by the attached functions. It is used by the mp-channel to identify each net device to make sure that only active net devices are writing to the channel

TracedCallback<Ptr<const Packet> > ns3::CsmaNetDevice::m_dropTrace [private]

The trace source for the packet drop events that the device can fire.

See also:: class CallBackTraceSource

CsmaEncapsulationMode ns3::CsmaNetDevice::m_encapMode [private]

The type of packet that should be created by the AddHeader function and that should be processed by the ProcessHeader function.

uint32_t ns3::CsmaNetDevice::m_ifIndex [private]

The interface index (really net evice index) that has been assigned to this network device.

Callback<void> ns3::CsmaNetDevice::m_linkChangeCallback [private]

Callback to fire if the link changes state (up or down).

bool ns3::CsmaNetDevice::m_linkUp [private]

Flag indicating whether or not the link is up. In this case, whether or not the device is connected to a channel.

uint16_t ns3::CsmaNetDevice::m_mtu [private]

The maximum transmission unit (biggest packet) allowed to be sent or received by this network device.

std::string ns3::CsmaNetDevice::m_name [private]

The human readable name of this device.

Ptr<Node> ns3::CsmaNetDevice::m_node [private]

The Node to which this device is attached.

Ptr<Queue> ns3::CsmaNetDevice::m_queue [private]

The Queue which this CsmaNetDevice uses as a packet source. Management of this Queue has been delegated to the CsmaNetDevice and it has the responsibility for deletion.