Several exchange methods of the switch

Cut Through

A straight-through Ethernet switch can be understood as a line matrix telephone switch that crosses between ports. When it detects a packet on the input port, it checks the packet header of the packet, obtains the destination address of the packet, starts the internal dynamic lookup table and converts it into the corresponding output port, connects it at the intersection of the input and output, and passes the packet to the packet. The corresponding port implements the switching function. Since it is not needed, the delay is very small and the exchange is very fast, which is its advantage. Its disadvantage is that because the contents of the packet are not stored and stored by the Ethernet switch, it is impossible to check whether the transmitted packet is incorrect or not, and cannot provide error detection capability. Since there is no buffer, it is not possible to directly connect input/output ports with different rates, and it is easy to drop packets.

Store & Forward

The store-and-forward method is the most widely used method in the field of computer networks. It checks the packet of the input port, takes out the destination address of the packet after processing the error packet, and converts it into an output port through the lookup table to send the packet. For this reason, the store-and-forward method has a large delay in data processing, which is its deficiency, but it can detect errors in packets entering the switch and effectively improve network performance. Especially important is that it can support the conversion between ports of different speeds, keeping the high-speed port and low-speed port work together.

Fragment Free

This is a solution between the first two. It checks if the length of the packet is 64 bytes. If it is less than 64 bytes, it is a fake packet, the packet is discarded; if it is larger than 64 bytes, the packet is sent. This method also does not provide data verification. Its data processing speed is faster than the store-and-forward method, but slower than the straight-through.