Difference Between Store‑and‑Forward Switching and Cut‑Through Switching
Switching is a technique that is used to transmit data between the networks. It is achieved by using switches that are used to connect multiple LAN networks. Switches forward the data packets based on their MAC addresses. Switching is used to efficiently utilize the bandwidth of the network and reduce the collisions between the packets. Switching techniques are of three types – circuit switching, message switching, and packet switching.
Switching modes are used to forward data packets by identifying different parts of the data frame such as preamble, a destination address, source address, ether type, data to be sent, and FCS. There are majorly two types of switching methods- cut-through switching and store-and-forward switching.
Store-and-forward switching is a method of switching data packets by the switching device that receives the data frame and then checks for errors before forwarding the packets. It supports the efficient transmission of non-corrupted frames. It is generally used in telecommunication networks.
In store-and-forward switching, the switching device waits to receive the entire frame and then stores the frame in the buffer memory. Then the frame is checked for errors by using CRC(Cyclic Redundancy Check) if the error is found then the packet is discarded else it is forwarded to the next device.
Cut-through switching is a method of switching data packets by the switching device that forwards the packets as soon as the destination address is available without waiting for the rest of the data to arrive. It supports low latency and high-speed transmission and requires less storage space. It is used in fiber channel transmission, SCSI traffic transmission, etc.
In cut−through switching, data transmission starts as soon as the destination address field arrives at the switching device. Then the device performs a lookup operation to check whether the destination address is valid or not. If the address is found valid and the link to the destination is available then the switching device starts to transmit the packets to the destination without waiting for the rest of the frame to arrive.
Difference between Cut-through Switching and Store-and-Forward Switching:
|The switching device waits to receive the entire frame before forwarding the data packet.||The switching device forwards the data packet as soon as the destination address is received and doesn’t wait for the entire frame to be received.|
|It supports error checking and collided/ bad frames are discarded before forwarding the packets.||There is no error-checking technique.|
|It checks for errors based on FCS bits of the data frame.||It relies on higher-level protocols to detect the error.|
|Frames are stored in the buffer memory of the switching device.||Frames are not stored in the switching device.|
|It is not further classified into different types.||Cut through switching is further classified as Rapid frame forwarding and Fragment free.|
|It has a high latency rate as the device waits for the entire frame to be received before sending the packets to the destination.||It has a low latency rate as the device does not wait for the entire frame to be received before sending the packets to the destination.|
|It is more secure as it does not forward corrupted frames to the destination.||It is less secure as it sometimes forwards corrupted frames to the destination.|
|It has a high waiting time as the switching device waits for the entire frame to be received before forwarding it.||It has a low waiting time as it forwards the frame as soon as the destination address is received.|
|It does not limit routing or arbitration decisions in switches.||It puts a limit on routing or arbitration decisions in switches between source and destination.|
|It has networks with more storage requirements.||It has less storage requirement.|
|Example: Telecommunication networks or transmission across networks requiring high mobility.||Example: Communication via fiber channel and low latency transmission for SCSI transmission.|
Store-and-forward switching and cut-through switching are two different methods used in network switches to forward packets from source to destination. The key differences between them are as follows:
- Delay: Store-and-forward switches store the entire packet before forwarding it to the next hop, whereas cut-through switches start forwarding the packet as soon as the destination address is received. As a result, store-and-forward switches have higher delay but lower error rates compared to cut-through switches.
- Error Handling: Store-and-forward switches can detect errors in the entire packet before forwarding it, and can discard or retransmit the packet if an error is detected. Cut-through switches, on the other hand, do not perform error checking and may forward packets with errors.
- Packet Size: Store-and-forward switches can handle packets of any size, whereas cut-through switches can only handle packets that are larger than a certain threshold. This is because cut-through switches only forward a packet after receiving the destination address, and if the packet is too short, the entire packet might be already forwarded before the switch can detect errors.
- Throughput: Cut-through switches have higher throughput than store-and-forward switches because they start forwarding packets as soon as they receive the destination address. Store-and-forward switches have higher delay because they store the entire packet before forwarding it, and this delay limits the overall throughput of the switch.
In summary, store-and-forward switching is more reliable and can handle packets of any size, but has higher delay and lower throughput compared to cut-through switching. Cut-through switching has higher throughput, but may forward packets with errors and can only handle packets above a certain size threshold.
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