Switching modes of industrial grade switches

Switching mode of a switch

Switches are exchanged in three ways:

1) straight through type:

Through Ethernet switches can be understood as line matrix telephone switches between vertical and horizontal ports. It is a data packet at the input port detection, check the Baotou package, to obtain the address, start the internal dynamic lookup table into the appropriate output port, connected at the intersection of the input and output of the data packets through the corresponding port, to achieve the exchange function. Because it does not require storage, the delay is very small and the exchange is very fast, which is its advantage. Its disadvantage is that, because the packet content has not been saved by Ethernet switches, it is impossible to check whether the transmitted packets are wrong and cannot provide error detection capability. Because there is no cache, the input / output ports with different speeds are not connected directly and are prone to packet loss.

2) store and forward:

Store and forward is the most widely used method in the computer network field. The input port of the first packet stored, then the CRC (cyclic redundancy check) check, just take out the packet‘s destination address in the packet processing of error, through the look-up table into an output port to send packet. Because of this, the storage and forwarding method has a large delay in data processing, which is its insufficiency. However, it can detect the data packet of the switch and improve the network performance effectively. Especially important is that it can support the conversion between ports at different speeds and maintain the cooperation between high speed ports and low speed ports.

3) debris isolation:

This is a solution between the first two. It checks whether the length of the packet is 64 bytes, and if less than 64 bytes, it means false packets and discards the packet; if it is greater than 64 bytes, the packet is sent. This method does not provide data validation. Its data processing speed is faster than store and forward, but slower than through.