A Device for a Csma Network Link. More...
#include <csma-net-device.h>
Public Types | |
enum | EncapsulationMode { ILLEGAL, DIX, 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, Ptr< CsmaNetDevice > sender) |
bool | IsSendEnabled (void) |
void | SetSendEnable (bool enable) |
bool | IsReceiveEnabled (void) |
void | SetReceiveEnable (bool enable) |
void | SetAddress (Mac48Address addr) |
void | SetFrameSize (uint16_t frameSize) |
uint16_t | GetFrameSize (void) const |
void | SetEncapsulationMode (CsmaNetDevice::EncapsulationMode mode) |
CsmaNetDevice::EncapsulationMode | GetEncapsulationMode (void) |
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 bool | SetMtu (const uint16_t mtu) |
virtual uint16_t | GetMtu (void) const |
virtual Address | GetAddress (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 (Ipv4Address multicastGroup) const |
Make and return a MAC multicast address using the provided multicast group. | |
virtual bool | IsPointToPoint (void) const |
virtual bool | IsBridge (void) const |
virtual bool | Send (Ptr< Packet > packet, const Address &dest, uint16_t protocolNumber) |
virtual bool | SendFrom (Ptr< Packet > packet, const Address &source, 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) |
virtual Address | GetMulticast (Ipv6Address addr) const |
Get the MAC multicast address corresponding to the IPv6 address provided. | |
virtual void | SetPromiscReceiveCallback (PromiscReceiveCallback cb) |
virtual bool | SupportsSendFrom (void) const |
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 source, Mac48Address dest, uint16_t protocolNumber) |
bool | ProcessHeader (Ptr< Packet > p, uint16_t ¶m) |
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) |
uint32_t | MtuFromFrameSize (uint32_t frameSize) |
uint32_t | FrameSizeFromMtu (uint32_t mtu) |
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 |
EncapsulationMode | 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 |
NetDevice::PromiscReceiveCallback | m_promiscRxCallback |
uint32_t | m_ifIndex |
std::string | m_name |
bool | m_linkUp |
Callback< void > | m_linkChangeCallback |
uint32_t | m_frameSize |
uint32_t | m_mtu |
Static Private Attributes | |
static const uint16_t | DEFAULT_FRAME_SIZE = 1518 |
static const uint16_t | ETHERNET_OVERHEAD = 18 |
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.
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
Definition at line 57 of file csma-net-device.h.
Enumeration of the types of packets supported in the class.
ILLEGAL |
Encapsulation mode not set |
DIX |
DIX II / Ethernet II packet |
LLC |
802.2 LLC/SNAP Packet |
Definition at line 66 of file csma-net-device.h.
enum ns3::CsmaNetDevice::TxMachineState [private] |
Enumeration of the states of the transmit machine of the net device.
Definition at line 574 of file csma-net-device.h.
ns3::CsmaNetDevice::CsmaNetDevice | ( | ) |
Construct a CsmaNetDevice
This is the default constructor for a CsmaNetDevice.
Definition at line 95 of file csma-net-device.cc.
References DEFAULT_FRAME_SIZE, DIX, m_channel, m_encapMode, m_frameSize, m_mtu, m_tInterframeGap, m_txMachineState, MtuFromFrameSize(), NS_LOG_FUNCTION, READY, and ns3::Seconds().
ns3::CsmaNetDevice::~CsmaNetDevice | ( | ) | [virtual] |
Destroy a CsmaNetDevice
This is the destructor for a CsmaNetDevice.
Definition at line 116 of file csma-net-device.cc.
References m_queue, and NS_LOG_FUNCTION_NOARGS.
ns3::CsmaNetDevice::CsmaNetDevice | ( | const CsmaNetDevice & | o | ) | [private] |
Copy constructor is declared but not implemented. This disables the copy constructor for CsmaNetDevice objects.
void ns3::CsmaNetDevice::AddHeader | ( | Ptr< Packet > | p, | |
Mac48Address | source, | |||
Mac48Address | dest, | |||
uint16_t | protocolNumber | |||
) | [protected] |
Adds the necessary headers and trailers to a packet of data in order to respect the packet type
p | Packet to which header should be added | |
source | MAC source address from which packet should be sent | |
dest | MAC destination address to which packet should be sent | |
protocolNumber | In some protocols, identifies the type of payload contained in this packet. |
Definition at line 314 of file csma-net-device.cc.
References ns3::EthernetTrailer::CalcFcs(), DIX, ILLEGAL, LLC, m_encapMode, m_frameSize, m_mtu, NS_ASSERT_MSG, NS_FATAL_ERROR, NS_LOG_FUNCTION, NS_LOG_LOGIC, ns3::EthernetHeader::SetDestination(), ns3::EthernetHeader::SetLengthType(), ns3::EthernetHeader::SetSource(), and ns3::LlcSnapHeader::SetType().
Referenced by SendFrom().
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.
ch | a pointer to the channel to which this object is being attached. |
Definition at line 558 of file csma-net-device.cc.
References ns3::DataRate::CalculateTxTime(), m_bps, m_channel, m_deviceId, m_tInterframeGap, NotifyLinkUp(), NS_LOG_FUNCTION, and ns3::Seconds().
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.
Definition at line 123 of file csma-net-device.cc.
References m_channel, m_node, and NS_LOG_FUNCTION_NOARGS.
uint32_t ns3::CsmaNetDevice::FrameSizeFromMtu | ( | uint32_t | mtu | ) | [private] |
Calculate the value for the frame size that would be required to be able to set the MTU to the given value.
Definition at line 165 of file csma-net-device.cc.
References DIX, ETHERNET_OVERHEAD, ns3::LlcSnapHeader::GetSerializedSize(), ILLEGAL, LLC, m_encapMode, NS_FATAL_ERROR, and NS_LOG_FUNCTION.
Referenced by SetMtu().
Address ns3::CsmaNetDevice::GetAddress | ( | void | ) | const [virtual] |
Implements ns3::NetDevice.
Definition at line 775 of file csma-net-device.cc.
References m_address, and NS_LOG_FUNCTION_NOARGS.
Referenced by ProcessHeader(), and Receive().
Address ns3::CsmaNetDevice::GetBroadcast | ( | void | ) | const [virtual] |
Calling this method is invalid if IsBroadcast returns not true.
Implements ns3::NetDevice.
Definition at line 803 of file csma-net-device.cc.
References NS_LOG_FUNCTION_NOARGS.
Referenced by ProcessHeader().
Implements ns3::NetDevice.
Definition at line 768 of file csma-net-device.cc.
References m_channel, and NS_LOG_FUNCTION_NOARGS.
CsmaNetDevice::EncapsulationMode ns3::CsmaNetDevice::GetEncapsulationMode | ( | void | ) |
Get the encapsulation mode of this device.
Definition at line 205 of file csma-net-device.cc.
References m_encapMode, and NS_LOG_FUNCTION_NOARGS.
uint16_t ns3::CsmaNetDevice::GetFrameSize | ( | void | ) | const |
Get The max frame size of packets sent over this device.
Definition at line 255 of file csma-net-device.cc.
References m_frameSize.
Referenced by GetTypeId().
uint32_t ns3::CsmaNetDevice::GetIfIndex | ( | void | ) | const [virtual] |
Implements ns3::NetDevice.
Definition at line 761 of file csma-net-device.cc.
References m_ifIndex, and NS_LOG_FUNCTION_NOARGS.
uint16_t ns3::CsmaNetDevice::GetMtu | ( | void | ) | const [virtual] |
This value is typically used by the IP layer to perform IP fragmentation when needed.
Implements ns3::NetDevice.
Definition at line 235 of file csma-net-device.cc.
References m_mtu, and NS_LOG_FUNCTION_NOARGS.
Address ns3::CsmaNetDevice::GetMulticast | ( | Ipv6Address | addr | ) | const [virtual] |
Get the MAC multicast address corresponding to the IPv6 address provided.
addr | IPv6 address |
Implements ns3::NetDevice.
Definition at line 950 of file csma-net-device.cc.
References GetMulticast(), and NS_LOG_LOGIC.
Address ns3::CsmaNetDevice::GetMulticast | ( | 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.
multicastGroup | The IP address for the multicast group destination of the packet. |
Implements ns3::NetDevice.
Definition at line 817 of file csma-net-device.cc.
References NS_LOG_FUNCTION, and NS_LOG_LOGIC.
Referenced by GetMulticast().
std::string ns3::CsmaNetDevice::GetName | ( | void | ) | const [virtual] |
Implements ns3::NetDevice.
Definition at line 747 of file csma-net-device.cc.
References m_name, and NS_LOG_FUNCTION_NOARGS.
Get the node to which this device is attached.
Implements ns3::NetDevice.
Definition at line 903 of file csma-net-device.cc.
References m_node, and NS_LOG_FUNCTION_NOARGS.
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.
Definition at line 721 of file csma-net-device.cc.
References m_queue, and NS_LOG_FUNCTION_NOARGS.
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:
Attributes defined for this type:
Attributes defined in parent class ns3::NetDevice:
TraceSources defined for this type:
Reimplemented from ns3::NetDevice.
Definition at line 43 of file csma-net-device.cc.
References ns3::TypeId::AddAttribute(), ns3::TypeId::AddTraceSource(), DEFAULT_FRAME_SIZE, DIX, GetFrameSize(), LLC, m_address, m_dropTrace, m_queue, m_receiveEnable, m_receiveErrorModel, m_rxTrace, m_sendEnable, ns3::MakeEnumAccessor(), ns3::MakeEnumChecker(), ns3::MakeTraceSourceAccessor(), SetEncapsulationMode(), SetFrameSize(), and ns3::TypeId::SetParent().
void ns3::CsmaNetDevice::Init | ( | bool | sendEnable, | |
bool | receiveEnable | |||
) | [private] |
Initialization function used during object construction.
bool ns3::CsmaNetDevice::IsBridge | ( | void | ) | const [virtual] |
Is this a bridge?
Implements ns3::NetDevice.
Definition at line 841 of file csma-net-device.cc.
References NS_LOG_FUNCTION_NOARGS.
bool ns3::CsmaNetDevice::IsBroadcast | ( | void | ) | const [virtual] |
Implements ns3::NetDevice.
Definition at line 796 of file csma-net-device.cc.
References NS_LOG_FUNCTION_NOARGS.
bool ns3::CsmaNetDevice::IsLinkUp | ( | void | ) | const [virtual] |
Implements ns3::NetDevice.
Definition at line 782 of file csma-net-device.cc.
References m_linkUp, and NS_LOG_FUNCTION_NOARGS.
Referenced by SendFrom().
bool ns3::CsmaNetDevice::IsMulticast | ( | void | ) | const [virtual] |
Implements ns3::NetDevice.
Definition at line 810 of file csma-net-device.cc.
References NS_LOG_FUNCTION_NOARGS.
bool ns3::CsmaNetDevice::IsPointToPoint | ( | void | ) | const [virtual] |
Is this a point to point link?
Implements ns3::NetDevice.
Definition at line 834 of file csma-net-device.cc.
References NS_LOG_FUNCTION_NOARGS.
bool ns3::CsmaNetDevice::IsReceiveEnabled | ( | void | ) |
Is the receive side of the network device enabled?
Definition at line 289 of file csma-net-device.cc.
References m_receiveEnable, and NS_LOG_FUNCTION_NOARGS.
Referenced by Receive().
bool ns3::CsmaNetDevice::IsSendEnabled | ( | void | ) |
Is the send side of the network device enabled?
Definition at line 282 of file csma-net-device.cc.
References m_sendEnable, and NS_LOG_FUNCTION_NOARGS.
Referenced by SendFrom(), and TransmitStart().
uint32_t ns3::CsmaNetDevice::MtuFromFrameSize | ( | uint32_t | frameSize | ) | [private] |
Calculate the value for the MTU that would result from setting the frame size to the given value.
Definition at line 132 of file csma-net-device.cc.
References DIX, ETHERNET_OVERHEAD, ns3::LlcSnapHeader::GetSerializedSize(), ILLEGAL, LLC, m_encapMode, NS_ASSERT_MSG, NS_FATAL_ERROR, and NS_LOG_FUNCTION.
Referenced by CsmaNetDevice(), SetEncapsulationMode(), and SetFrameSize().
bool ns3::CsmaNetDevice::NeedsArp | ( | void | ) | const [virtual] |
Does this device need to use the address resolution protocol?
Implements ns3::NetDevice.
Definition at line 937 of file csma-net-device.cc.
References NS_LOG_FUNCTION_NOARGS.
void ns3::CsmaNetDevice::NotifyLinkUp | ( | void | ) | [private] |
Notify any interested parties that the link has come up.
Definition at line 728 of file csma-net-device.cc.
References ns3::Callback< R, T1, T2, T3, T4, T5, T6, T7, T8, T9 >::IsNull(), m_linkChangeCallback, m_linkUp, and NS_LOG_FUNCTION_NOARGS.
Referenced by Attach().
CsmaNetDevice& ns3::CsmaNetDevice::operator= | ( | const CsmaNetDevice & | o | ) | [private] |
Operator = is declared but not implemented. This disables the assigment operator for CsmaNetDevice objects.
Removes, from a packet of data, all headers and trailers that relate to the packet type
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 |
Definition at line 371 of file csma-net-device.cc.
References ns3::EthernetTrailer::CheckFcs(), DIX, GetAddress(), GetBroadcast(), ns3::EthernetHeader::GetDestination(), ns3::EthernetHeader::GetLengthType(), ns3::LlcSnapHeader::GetType(), ILLEGAL, LLC, m_encapMode, NS_FATAL_ERROR, and NS_LOG_FUNCTION.
void ns3::CsmaNetDevice::Receive | ( | Ptr< Packet > | p, | |
Ptr< CsmaNetDevice > | sender | |||
) |
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.
p | a reference to the received packet | |
sender | the CsmaNetDevice that transmitted the packet in the first place |
Definition at line 598 of file csma-net-device.cc.
References ns3::EthernetTrailer::CheckFcs(), ns3::Mac48Address::CopyFrom(), ns3::Address::CopyTo(), DIX, GetAddress(), ns3::EthernetHeader::GetDestination(), ns3::EthernetHeader::GetLengthType(), ns3::EthernetHeader::GetSource(), ns3::LlcSnapHeader::GetType(), ILLEGAL, ns3::Mac48Address::IsBroadcast(), ns3::Mac48Address::IsMulticast(), ns3::Callback< R, T1, T2, T3, T4, T5, T6, T7, T8, T9 >::IsNull(), IsReceiveEnabled(), LLC, m_address, m_dropTrace, m_encapMode, m_promiscRxCallback, m_receiveErrorModel, m_rxCallback, m_rxTrace, NS_FATAL_ERROR, NS_LOG_FUNCTION, NS_LOG_LOGIC, ns3::NetDevice::PACKET_BROADCAST, ns3::NetDevice::PACKET_HOST, ns3::NetDevice::PACKET_MULTICAST, and ns3::NetDevice::PACKET_OTHERHOST.
bool ns3::CsmaNetDevice::Send | ( | Ptr< Packet > | packet, | |
const Address & | dest, | |||
uint16_t | protocolNumber | |||
) | [virtual] |
Start sending a packet down the channel.
Implements ns3::NetDevice.
Definition at line 848 of file csma-net-device.cc.
References m_address, NS_LOG_FUNCTION, and SendFrom().
bool ns3::CsmaNetDevice::SendFrom | ( | Ptr< Packet > | packet, | |
const Address & | source, | |||
const Address & | dest, | |||
uint16_t | protocolNumber | |||
) | [virtual] |
Start sending a packet down the channel, with MAC spoofing
Implements ns3::NetDevice.
Definition at line 855 of file csma-net-device.cc.
References AddHeader(), ns3::Mac48Address::ConvertFrom(), IsLinkUp(), IsSendEnabled(), m_currentPkt, m_queue, m_txMachineState, NS_ASSERT, NS_LOG_FUNCTION, NS_LOG_LOGIC, READY, and TransmitStart().
Referenced by Send().
void ns3::CsmaNetDevice::SetAddress | ( | Mac48Address | addr | ) |
Set the MAC address of the the network device.
addr | The Mac48Address to use as the address of the device. |
Definition at line 261 of file csma-net-device.cc.
References m_address, and NS_LOG_FUNCTION.
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.
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 |
Definition at line 303 of file csma-net-device.cc.
References m_backoff, ns3::Backoff::m_ceiling, ns3::Backoff::m_maxRetries, ns3::Backoff::m_maxSlots, ns3::Backoff::m_minSlots, ns3::Backoff::m_slotTime, and NS_LOG_FUNCTION.
void ns3::CsmaNetDevice::SetEncapsulationMode | ( | CsmaNetDevice::EncapsulationMode | mode | ) |
Set the encapsulation mode of this device.
mode | The encapsulation mode of this device. |
Definition at line 192 of file csma-net-device.cc.
References m_encapMode, m_frameSize, m_mtu, MtuFromFrameSize(), NS_LOG_FUNCTION, and NS_LOG_LOGIC.
Referenced by GetTypeId().
void ns3::CsmaNetDevice::SetFrameSize | ( | uint16_t | frameSize | ) |
Set The max frame size of packets sent over this device.
Okay, that was easy to say, but the details are a bit thorny. We have a MAC-level MTU that is the payload that higher level protocols see. We have a PHY-level MTU which is the maximum number of bytes we can send over the link (cf. 1500 bytes for Ethernet). We also have a frame size which is some total number of bytes in a packet which could or could not include any framing and overhead. There can be a lot of inconsistency in definitions of these terms. For example, RFC 1042 asserts that the terms maximum transmission unit and maximum packet size are equivalent. RFC 791, however, defines MTU as the maximum sized IP datagram that can be sent. Packet size and frame size are sometimes used interchangeably.
So, some careful definitions are in order to avoid confusion:
In real Ethernet, a packet on the wire starts with a preamble of seven bytes of alternating ones and zeroes followed by a Start-of-Frame-Delimeter (10101011). This is followed by what is usually called the packet: a MAC destination and source, a type field, payload, a possible padding field and a CRC. To be strictly and pedantically correct the frame size is necessarily larger than the packet size on a real Ethernet. But, this isn't a real Ethernet, it's a simulation of a device similar to Ethernet, and we have no good reason to add framing bits. So, in the case of the CSMA device, the frame size is equal to the packet size. Since these two values are equal, there is no danger in assuming they are identical. We do not implement any padding out to a minimum frame size, so padding is a non-issue. We define packet size to be equal to frame size and this excludes the preamble and SFD bytes of a real Ethernet frame. We define a single (MAC-level) MTU that coresponds to the payload size of the packet, which is the IP-centric view of the term as seen in RFC 791.
To make this concrete, consider DIX II (Digital Equipment, Intel, Xerox type II) framing, which is used in most TCP/IP stacks. NetWare and Wireshark call this framing Ethernet II, by the way. In this framing scheme, a real packet on the wire starts with the preamble and Start-of-Frame-Delimeter (10101011). We ignore these bits on this device since it they are not needed. In DIX II, the SFD is followed by the MAC (48) destination address (6 bytes), source address (6 bytes), the EtherType field (2 bytes), payload (0-1500 bytes) and a CRC (4 bytes) -- this corresponds to our entire frame. The payload of the packet/frame in DIX can be from 0 to 1500 bytes. It is the maxmimum value of this payload that we call the MTU. Typically, one sees the MTU set to 1500 bytes and the maximum frame size set to 1518 bytes in Ethernet-based networks.
Different framing schemes can make for different MTU and frame size relationships. For example, we support LLC/SNAP encapsulation which adds eight bytes of header overhead to the usual DIX framing. In this case, if the maximum frame size is left at 1518 bytes, we need to export an MTU that reflects the loss of eight bytes for a total of 1492.
Another complication is that IEEE 802.1Q adds four bytes to the maximum frame size for VLAN tagging. In order to provide an MTU of 1500 bytes, the frame size would need to increased to 1522 bytes to absorb the additional overhead.
So, there are really three variables that are not entirely free at work here. There is the maximum frame size, the MTU and the framing scheme which we call the encapsulation mode.
So, what do we do since there are be three values which must always be consistent in the driver? Which values to we allow to be changed and how do we ensure the other two are consistent? We want to actually allow a user to change these three variables in flexible ways, but we want the results (even at intermediate stages of her ultimate change) to be consistent. We certainly don't want to require that users must understand the various requirements of an enapsulation mode in order to set these variables.
Consider the following situation: A user wants to set the maximum frame size to 1418 bytes instead of 1518. This user shouldn't have to concern herself that the current encapuslation mode is LLC/SNAP and this will consume eight bytes. She should not have to also figure out that the MTU needs to be set to 1392 bytes, and she should certainly not have to do this in some special order to keep intermediate steps consistent.
Similarly, a user who is interested in setting the MTU to 1400 bytes should not be forced to understand that (based on encapsulation mode) the frame size may need to be set to eighteen + eight bytes more than what he wants in certain cases (802,3 + LLC/SNAP), twenty-two + zero bytes in others (802.1Q) and other inscrutable combinations
Now, consider a user who is only interested in changing the encapsulation mode from LLC/SNAP to DIX. This is going to change the relationship between the MTU and the frame size. We've may have to come up with a new value for at least one of the these? Which one? There are too many free variables.
We could play games trying to figure out what the user wants to do, but that is typically a bad plan and programmers have a long and distinguished history of guessing wrong. We'll avoid all of that and just define a flexible behavior that can be worked to get what you want. Here it is:
So, if a user calls SetFrameSize, we assume that the maximum frame size is the interesting thing for that user and we just adjust the MTU to a new "correct value" based on the current encapsulation mode. If a user calls SetMtu, we assume that the MTU is the interesting property for that user, and we adjust the frame size to a new "correct value" for the current encapsulation mode. If a user calls SetEncapsulationMode, then we take the MTU as the free variable and set its value to match the current frame size.
frameSize | The max frame size of packets sent over this device. |
Definition at line 242 of file csma-net-device.cc.
References m_encapMode, m_frameSize, m_mtu, MtuFromFrameSize(), NS_LOG_FUNCTION, and NS_LOG_LOGIC.
Referenced by GetTypeId().
void ns3::CsmaNetDevice::SetIfIndex | ( | const uint32_t | index | ) | [virtual] |
index | ifIndex of the device |
Implements ns3::NetDevice.
Definition at line 754 of file csma-net-device.cc.
References m_ifIndex, and NS_LOG_FUNCTION.
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.
t | the interframe gap time |
Definition at line 296 of file csma-net-device.cc.
References m_tInterframeGap, and NS_LOG_FUNCTION.
void ns3::CsmaNetDevice::SetLinkChangeCallback | ( | Callback< void > | callback | ) | [virtual] |
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.
Definition at line 789 of file csma-net-device.cc.
References m_linkChangeCallback, and NS_LOG_FUNCTION.
bool ns3::CsmaNetDevice::SetMtu | ( | const uint16_t | mtu | ) | [virtual] |
mtu | MTU value, in bytes, to set for the device |
Override for default MTU defined on a per-type basis.
Implements ns3::NetDevice.
Definition at line 212 of file csma-net-device.cc.
References FrameSizeFromMtu(), m_encapMode, m_frameSize, m_mtu, NS_LOG_FUNCTION, NS_LOG_LOGIC, and NS_LOG_WARN.
void ns3::CsmaNetDevice::SetName | ( | const std::string | name | ) | [virtual] |
name | name of the device (e.g. "eth0") |
Implements ns3::NetDevice.
Definition at line 740 of file csma-net-device.cc.
References m_name, and NS_LOG_FUNCTION.
Set the node to which this device is being attached.
Implements ns3::NetDevice.
Definition at line 910 of file csma-net-device.cc.
References m_name, m_node, NS_LOG_FUNCTION, and ns3::PeekPointer().
void ns3::CsmaNetDevice::SetPromiscReceiveCallback | ( | PromiscReceiveCallback | cb | ) | [virtual] |
cb | callback to invoke whenever a packet has been received in promiscuous mode and must be forwarded to the higher layers. |
Enables netdevice promiscuous mode and sets the callback that will handle promiscuous mode packets. Note, promiscuous mode packets means _all_ packets, including those packets that can be sensed by the netdevice but which are intended to be received by other hosts.
Implements ns3::NetDevice.
Definition at line 959 of file csma-net-device.cc.
References m_promiscRxCallback, and NS_LOG_FUNCTION.
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.
queue | a Ptr to the queue for being assigned to the device. |
Definition at line 584 of file csma-net-device.cc.
References m_queue, and NS_LOG_FUNCTION.
void ns3::CsmaNetDevice::SetReceiveCallback | ( | NetDevice::ReceiveCallback | cb | ) | [virtual] |
Set the callback to be used to notify higher layers when a packet has been received.
cb | The callback. |
Implements ns3::NetDevice.
Definition at line 944 of file csma-net-device.cc.
References m_rxCallback, and NS_LOG_FUNCTION.
void ns3::CsmaNetDevice::SetReceiveEnable | ( | bool | enable | ) |
Enable or disable the receive side of the network device.
enable | Enable the receive side if true, otherwise disable. |
Definition at line 275 of file csma-net-device.cc.
References m_receiveEnable, and NS_LOG_FUNCTION.
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.
em | a pointer to the ErrorModel |
Definition at line 591 of file csma-net-device.cc.
References m_receiveErrorModel, and NS_LOG_FUNCTION.
void ns3::CsmaNetDevice::SetSendEnable | ( | bool | enable | ) |
Enable or disable the send side of the network device.
enable | Enable the send side if true, otherwise disable. |
Definition at line 268 of file csma-net-device.cc.
References m_sendEnable, and NS_LOG_FUNCTION.
bool ns3::CsmaNetDevice::SupportsSendFrom | ( | void | ) | const [virtual] |
Implements ns3::NetDevice.
Definition at line 966 of file csma-net-device.cc.
References NS_LOG_FUNCTION_NOARGS.
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.
Definition at line 486 of file csma-net-device.cc.
References m_backoff, m_currentPkt, m_queue, m_txMachineState, NS_ASSERT_MSG, NS_LOG_FUNCTION_NOARGS, NS_LOG_LOGIC, READY, ns3::Backoff::ResetBackoffTime(), and TransmitStart().
Referenced by TransmitStart().
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.
Definition at line 507 of file csma-net-device.cc.
References BUSY, GAP, ns3::TimeUnit< 1 >::GetSeconds(), m_channel, m_currentPkt, m_tInterframeGap, m_txMachineState, NS_ASSERT, NS_ASSERT_MSG, NS_LOG_FUNCTION_NOARGS, NS_LOG_LOGIC, ns3::Simulator::Schedule(), TransmitReadyEvent(), and ns3::TRANSMITTING.
Referenced by TransmitStart().
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.
Definition at line 530 of file csma-net-device.cc.
References GAP, m_currentPkt, m_queue, m_txMachineState, NS_ASSERT_MSG, NS_LOG_FUNCTION_NOARGS, READY, and TransmitStart().
Referenced by TransmitCompleteEvent().
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).
Definition at line 410 of file csma-net-device.cc.
References BACKOFF, BUSY, ns3::DataRate::CalculateTxTime(), ns3::Backoff::GetBackoffTime(), ns3::TimeUnit< 1 >::GetSeconds(), ns3::IDLE, ns3::Backoff::IncrNumRetries(), IsSendEnabled(), m_backoff, m_bps, m_channel, m_currentPkt, m_deviceId, m_txMachineState, ns3::Backoff::MaxRetriesReached(), NS_ASSERT_MSG, NS_LOG_FUNCTION_NOARGS, NS_LOG_LOGIC, NS_LOG_WARN, READY, ns3::Backoff::ResetBackoffTime(), ns3::Simulator::Schedule(), ns3::Seconds(), TransmitAbort(), and TransmitCompleteEvent().
Referenced by SendFrom(), TransmitAbort(), and TransmitReadyEvent().
const uint16_t ns3::CsmaNetDevice::DEFAULT_FRAME_SIZE = 1518 [static, private] |
Definition at line 701 of file csma-net-device.h.
Referenced by CsmaNetDevice(), and GetTypeId().
const uint16_t ns3::CsmaNetDevice::ETHERNET_OVERHEAD = 18 [static, private] |
Definition at line 702 of file csma-net-device.h.
Referenced by FrameSizeFromMtu(), and MtuFromFrameSize().
Mac48Address ns3::CsmaNetDevice::m_address [private] |
The MAC address which has been assigned to this device.
Definition at line 668 of file csma-net-device.h.
Referenced by GetAddress(), GetTypeId(), Receive(), Send(), and SetAddress().
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
Definition at line 614 of file csma-net-device.h.
Referenced by SetBackoffParams(), TransmitAbort(), and TransmitStart().
DataRate ns3::CsmaNetDevice::m_bps [private] |
The data rate that the Net Device uses to simulate packet transmission timing.
Definition at line 600 of file csma-net-device.h.
Referenced by Attach(), and TransmitStart().
Ptr<CsmaChannel> ns3::CsmaNetDevice::m_channel [private] |
The CsmaChannel to which this CsmaNetDevice has been attached.
Definition at line 628 of file csma-net-device.h.
Referenced by Attach(), CsmaNetDevice(), DoDispose(), GetChannel(), TransmitCompleteEvent(), and TransmitStart().
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.
Definition at line 621 of file csma-net-device.h.
Referenced by SendFrom(), TransmitAbort(), TransmitCompleteEvent(), TransmitReadyEvent(), and TransmitStart().
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
Definition at line 559 of file csma-net-device.h.
Referenced by Attach(), and TransmitStart().
TracedCallback<Ptr<const Packet> > ns3::CsmaNetDevice::m_dropTrace [private] |
The trace source for the packet drop events that the device can fire.
Definition at line 658 of file csma-net-device.h.
Referenced by GetTypeId(), and Receive().
The type of packet that should be created by the AddHeader function and that should be processed by the ProcessHeader function.
Definition at line 593 of file csma-net-device.h.
Referenced by AddHeader(), CsmaNetDevice(), FrameSizeFromMtu(), GetEncapsulationMode(), MtuFromFrameSize(), ProcessHeader(), Receive(), SetEncapsulationMode(), SetFrameSize(), and SetMtu().
uint32_t ns3::CsmaNetDevice::m_frameSize [private] |
The frame size/packet size. This corresponds to the maximum number of bytes that can be transmitted as a packet without framing. This corresponds to the 1518 byte packet size often seen on Ethernet.
Definition at line 709 of file csma-net-device.h.
Referenced by AddHeader(), CsmaNetDevice(), GetFrameSize(), SetEncapsulationMode(), SetFrameSize(), and SetMtu().
uint32_t ns3::CsmaNetDevice::m_ifIndex [private] |
The interface index (really net evice index) that has been assigned to this network device.
Definition at line 683 of file csma-net-device.h.
Referenced by GetIfIndex(), and SetIfIndex().
Callback<void> ns3::CsmaNetDevice::m_linkChangeCallback [private] |
Callback to fire if the link changes state (up or down).
Definition at line 699 of file csma-net-device.h.
Referenced by NotifyLinkUp(), and SetLinkChangeCallback().
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.
Definition at line 694 of file csma-net-device.h.
Referenced by IsLinkUp(), and NotifyLinkUp().
uint32_t ns3::CsmaNetDevice::m_mtu [private] |
The Maxmimum Transmission Unit. This corresponds to the maximum number of bytes that can be transmitted as seen from higher layers. This corresponds to the 1500 byte MTU size often seen on IP over Ethernet.
Definition at line 717 of file csma-net-device.h.
Referenced by AddHeader(), CsmaNetDevice(), GetMtu(), SetEncapsulationMode(), SetFrameSize(), and SetMtu().
std::string ns3::CsmaNetDevice::m_name [private] |
The human readable name of this device.
Definition at line 688 of file csma-net-device.h.
Ptr<Node> ns3::CsmaNetDevice::m_node [private] |
The Node to which this device is attached.
Definition at line 663 of file csma-net-device.h.
Referenced by DoDispose(), GetNode(), and SetNode().
The callback used to notify higher layers that a packet has been received in promiscuous mode.
Definition at line 677 of file csma-net-device.h.
Referenced by Receive(), and SetPromiscReceiveCallback().
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.
Definition at line 637 of file csma-net-device.h.
Referenced by GetQueue(), GetTypeId(), SendFrom(), SetQueue(), TransmitAbort(), TransmitReadyEvent(), and ~CsmaNetDevice().
bool ns3::CsmaNetDevice::m_receiveEnable [private] |
Enable net device to receive packets. True by default
Definition at line 569 of file csma-net-device.h.
Referenced by GetTypeId(), IsReceiveEnabled(), and SetReceiveEnable().
Ptr<ErrorModel> ns3::CsmaNetDevice::m_receiveErrorModel [private] |
Error model for receive packet events
Definition at line 642 of file csma-net-device.h.
Referenced by GetTypeId(), Receive(), and SetReceiveErrorModel().
The callback used to notify higher layers that a packet has been received.
Definition at line 673 of file csma-net-device.h.
Referenced by Receive(), and SetReceiveCallback().
TracedCallback<Ptr<const Packet> > ns3::CsmaNetDevice::m_rxTrace [private] |
The trace source for the packet reception events that the device can fire.
Definition at line 650 of file csma-net-device.h.
Referenced by GetTypeId(), and Receive().
bool ns3::CsmaNetDevice::m_sendEnable [private] |
Enable net device to send packets. True by default
Definition at line 564 of file csma-net-device.h.
Referenced by GetTypeId(), IsSendEnabled(), and SetSendEnable().
Time ns3::CsmaNetDevice::m_tInterframeGap [private] |
The interframe gap that the Net Device uses insert time between packet transmission
Definition at line 607 of file csma-net-device.h.
Referenced by Attach(), CsmaNetDevice(), SetInterframeGap(), and TransmitCompleteEvent().
The state of the Net Device transmit state machine.
Definition at line 586 of file csma-net-device.h.
Referenced by CsmaNetDevice(), SendFrom(), TransmitAbort(), TransmitCompleteEvent(), TransmitReadyEvent(), and TransmitStart().