20 * |
20 * |
21 * \subsection CSMA Channel Model |
21 * \subsection CSMA Channel Model |
22 * |
22 * |
23 * The class ns3::CsmaChannel models the actual transmission medium. |
23 * The class ns3::CsmaChannel models the actual transmission medium. |
24 * There is no fixed limit for the number of devices connected to the channel. |
24 * There is no fixed limit for the number of devices connected to the channel. |
25 * The ns3::CsmaChannel models a bitrate and a speed-of-light delay which can |
25 * The ns3::CsmaChannel models a data rate and a speed-of-light delay which can |
26 * be accessed via the attributes "BitRate" and "Delay" respectively. |
26 * be accessed via the attributes "DataRate" and "Delay" respectively. |
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27 * The data rate provided to the channel is used to set the data rates |
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28 * used by the transmitter sections of the CSMA devices connected to the |
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29 * channel. There is no way to independently set data rates in the |
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30 * devices. Since the data rate is only used to calculate a delay time, there |
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31 * is no limitation (other than by the data type holding the value) on the |
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32 * speed at which CSMA channels and devices can operate. |
27 * |
33 * |
28 * The ns3::CsmaChannel has three states, IDLE, TRANSMITTING and PROPAGATING. |
34 * The ns3::CsmaChannel has three states, IDLE, TRANSMITTING and PROPAGATING. |
29 * These three states are "seen" instantaneously by all devices on the channel. |
35 * These three states are "seen" instantaneously by all devices on the channel. |
30 * By this we mean that if one device begins or ends a simulated transmission, |
36 * By this we mean that if one device begins or ends a simulated transmission, |
31 * all devices on the channel are immediately aware of the change in state. |
37 * all devices on the channel are immediately aware of the change in state. |
60 * in which the packet bits propagate to a central location and then back out |
66 * in which the packet bits propagate to a central location and then back out |
61 * equal length cables to the other devices on the channel. |
67 * equal length cables to the other devices on the channel. |
62 * |
68 * |
63 * The ns3::CsmaChannel models a broadcast medium so the packet is delivered |
69 * The ns3::CsmaChannel models a broadcast medium so the packet is delivered |
64 * to all of the devices on the channel (including the source) at the end of |
70 * to all of the devices on the channel (including the source) at the end of |
65 * the propagation time. |
71 * the propagation time. It is the responsibility of the sending device to |
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72 * determine whether or not it receives a packet broadcast over the channel. |
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73 * |
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74 * The ns3::CsmaChannel provides following Attributes: |
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75 * |
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76 * - DataRate: The bitrate for packet transmission on connected devices; |
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77 * - Delay: The speed of light transmission delay for the channel. |
66 * |
78 * |
67 * \subsection CSMA Net Device Model |
79 * \subsection CSMA Net Device Model |
68 * |
80 * |
69 * The CSMA network device appears somewhat like an Ethernet device. The |
81 * The CSMA network device appears somewhat like an Ethernet device. The |
70 * ns3::CsmaNetDevice provides following Attributes: |
82 * ns3::CsmaNetDevice provides following Attributes: |
71 * |
83 * |
72 * - Address: The ns3::Mac48Address of the device; |
84 * - Address: The ns3::Mac48Address of the device; |
73 * - DataRate: The data rate of the device; |
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74 * - SendEnable: Enable packet transmission if true; |
85 * - SendEnable: Enable packet transmission if true; |
75 * - ReceiveEnable: Enable packet reception if true; |
86 * - ReceiveEnable: Enable packet reception if true; |
76 * - EncapsulationMode: Type of link layer encapsulation to use; |
87 * - EncapsulationMode: Type of link layer encapsulation to use; |
77 * - RxErrorModel: The receive error model; |
88 * - RxErrorModel: The receive error model; |
78 * - TxQueue: The trasmit queue used by the device; |
89 * - TxQueue: The trasmit queue used by the device; |