CSMA/CD - Elements of the networks 802.3/Ethernet
When you start working in the area of networks is important to know some basics about the operation of Ethernet networks. Important aspects in the design and implementation of switching networks.
CSMA / CD
Ethernet signals are transmitted to all hosts that are connected to the LAN through a set of special rules to determine which station can access the network. The set of rules that uses Ethernet technology is based on carrier sense multiple access and collision detection (CSMA/CD) IEEE. You may remember CCNA Exploration: Network Fundamentals, CSMA/CD is used only half-duplex communication is usually found in the hubs. The switches do not use full-duplex CSMA/CD.
Carrier Detect
In the access method CSMA/CD, all network devices that have a message to send should listen before transmitting.
If a device detects a signal from another device, wait a certain period before attempting to transmit.
When not detected any traffic, the device transmits its message. While such a transfer occurs, the device continues monitoring traffic or collisions on the LAN. After sending the message, the device returns to the default listener.
Multiple Access
If the distance between the devices is such that the latency of the signals of a device is no detection of these by a second device, it could also begin to transmit. Thus, the medium would have two devices transmitting signals at the same time. The messages are spread across the medium until they meet. At that time, the signals are mixed and the messages are destroyed: a collision occurs. Although messages are damaged, the mixed signals continues to spread throughout the medium.
Collision Detection
When a device is in listening mode, can detect when a collision on the shared medium. This is because all devices can detect an increase in the amplitude of the signal is above the normal level.
When a collision occurs, other devices are in listening mode, as well as all transmitting devices, detect the increase in amplitude of the signal. All devices are transmitting at that time, they will do to ensure that all devices on the network can detect the collision.
Congestion signal and delay random
When a collision is detected, the transmitting devices send a signal of congestion. Congestion signal, notifies the other devices on the collision so that they invoke a Backoff Algorithm. The function of this is to make all devices stop transmission during a random period, thereby reducing the signs of a collision.
After ending the delay assigned to a device, the device returns to "listen before transmit." A random delay period ensures that the devices involved in the collision does not attempt to send traffic back at the same time, leading to repeat the whole process. However, during the period of postponement is possible that a third device to transmit before either involved in the collision have a chance to re-transmit.
CSMA / CD
Ethernet signals are transmitted to all hosts that are connected to the LAN through a set of special rules to determine which station can access the network. The set of rules that uses Ethernet technology is based on carrier sense multiple access and collision detection (CSMA/CD) IEEE. You may remember CCNA Exploration: Network Fundamentals, CSMA/CD is used only half-duplex communication is usually found in the hubs. The switches do not use full-duplex CSMA/CD.
Carrier Detect
In the access method CSMA/CD, all network devices that have a message to send should listen before transmitting.
If a device detects a signal from another device, wait a certain period before attempting to transmit.
When not detected any traffic, the device transmits its message. While such a transfer occurs, the device continues monitoring traffic or collisions on the LAN. After sending the message, the device returns to the default listener.
Multiple Access
If the distance between the devices is such that the latency of the signals of a device is no detection of these by a second device, it could also begin to transmit. Thus, the medium would have two devices transmitting signals at the same time. The messages are spread across the medium until they meet. At that time, the signals are mixed and the messages are destroyed: a collision occurs. Although messages are damaged, the mixed signals continues to spread throughout the medium.
Collision Detection
When a device is in listening mode, can detect when a collision on the shared medium. This is because all devices can detect an increase in the amplitude of the signal is above the normal level.
When a collision occurs, other devices are in listening mode, as well as all transmitting devices, detect the increase in amplitude of the signal. All devices are transmitting at that time, they will do to ensure that all devices on the network can detect the collision.
Congestion signal and delay random
When a collision is detected, the transmitting devices send a signal of congestion. Congestion signal, notifies the other devices on the collision so that they invoke a Backoff Algorithm. The function of this is to make all devices stop transmission during a random period, thereby reducing the signs of a collision.
After ending the delay assigned to a device, the device returns to "listen before transmit." A random delay period ensures that the devices involved in the collision does not attempt to send traffic back at the same time, leading to repeat the whole process. However, during the period of postponement is possible that a third device to transmit before either involved in the collision have a chance to re-transmit.
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