Switches connect computers in a network or different segment of the same network. Switches work at the data link layer of the OSI reference model. So, Switches treat data in the form of frames and not as signals, which is the case with physical layer devices like hubs. A data frame contains information about the MAC address of the destination computer. Switches can read this MAC address and as a result, forward the data only to the port that is associated with this MAC address. for this purpose, switches maintain a list of MAC addresses and port number associated with each MAC address.
Switches work at the data link layer. Therefore, they convert the signal to data frame, check the destination MAC address of the frame, and reconvert the frame into a signal. As a result, switches regenerate the signal as opposed to hubs or repeaters, which amplify the signals.
Switches use any of the following two methods to transmit data:
Computers are connected using a switch. Assume that Node A sends data to Node C. The data from Node A reaches the switch from Host-1 in the form of a data frame. The switch then reads the destination MAC address and from the list of MAC addresses, the switch known that the data is meant for Node C. as Node C is associated with port-3 the switch forwards the data only to Port-3. The data is converted back into a signal and transmitted to Node C.
Both methods of switching have advantages as well as disadvantages. In cut-through switching, the switch forwards the frame as soon as it receives the frame, and therefore, the data transfer rate is not affected. However, this methods does not employ any error-checking mechanisms, and as a result, corrupt frames may be forwarded to the destination. The destination computer sends an error report to the source computer, and the corrupt data frame needs to be sent again resulting in unnecessary network traffic.
Store-and-forward switching ensures that corrupt frames are dropped and only error-free data is forwarded. However, store and forward switching is slower because each frame is checked for integrity, and the data is forwarded only after the switch received all the frames.
Depending on the requirements of the network, you can select an appropriate methods of switching. For example, if the speed of the network is the primary concern, you can select cut-through switching. Most switches, however, have the ability to select an appropriate switching method depending on the network conditions. Initially, the switch uses cut-through switching, but if it finds that the number of corrupt data frames is high, it automatically selects store-and-forward switching. After some time, if the switch observes that the number of corrupt data frames is lower, the switch reverts back to cut-through switching. This is called as auto switching.
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Neel Kamal
Switches use any of the following two methods to transmit data:
- Cut-through switching : In this methods, the switch reads the destination MAC address of a data frame and immediately forwards the frame to the respective port.
- Store-and-forward switching: In this methods, the switch receives all the data frames corresponding to a particular transmission. the frames are then checked for integrity and errors. If the frames are found to be error-free, the switch forwards the frames to the respective port. If the frames are corrupt, they are not forwarded to the destination, and the source device has to resend the frames.
Packet Switching
Both methods of switching have advantages as well as disadvantages. In cut-through switching, the switch forwards the frame as soon as it receives the frame, and therefore, the data transfer rate is not affected. However, this methods does not employ any error-checking mechanisms, and as a result, corrupt frames may be forwarded to the destination. The destination computer sends an error report to the source computer, and the corrupt data frame needs to be sent again resulting in unnecessary network traffic.
Store-and-forward switching ensures that corrupt frames are dropped and only error-free data is forwarded. However, store and forward switching is slower because each frame is checked for integrity, and the data is forwarded only after the switch received all the frames.
Depending on the requirements of the network, you can select an appropriate methods of switching. For example, if the speed of the network is the primary concern, you can select cut-through switching. Most switches, however, have the ability to select an appropriate switching method depending on the network conditions. Initially, the switch uses cut-through switching, but if it finds that the number of corrupt data frames is high, it automatically selects store-and-forward switching. After some time, if the switch observes that the number of corrupt data frames is lower, the switch reverts back to cut-through switching. This is called as auto switching.
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Thanks a lot for reading!
Neel Kamal
Identify the function of SWITCHES in a network
Reviewed by Neel Kamal
on
November 30, 2018
Rating:
Reviewed by Neel Kamal
on
November 30, 2018
Rating:
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