
Introduction to Switching Modes
Data transmission and error checking on transmitted and received frames are handled by Layer 2 switches(see Switching) on the data connection layer. The MAC address determines how Layer 2 switches forward packets. The different packet-forwarding modes are referred to as switching modes.
Switching mode distinguishes between different parts of a frame. The numerous components that make up the frame (FCS) are a preamble, the destination MAC address, the source MAC address, the user's data, and the Frame Check Sequence are the numerous components that make up the frame (FCS).

Types of Switching Modes
There are mainly 3 types of Switching Modes:
- Store and Forward
- Cut Through
- Fragment Free.
Store and Forward Switching
Store and forward packet switching is a telecommunications technology in which data packets are kept at each intermediate node before being transferred to the next node. Before sending, the intermediary node verifies that the packet is error-free, assuring data packet integrity. In general, the network layer functions in a store-and-forward packet switching context.

Working Principle
The node that has a packet to transmit sends it to the router, the closest node. The packet is held in the router until it has arrived in its entirety, at which point its checksum is checked for error detection. The packet is then sent to the next router when this is completed. Each router repeats the procedure until the packet arrives at its destination.

Working of Store and Forward mode Switching
The Internet Service Provider (ISP) has six routers (A to F) linked by transmission lines illustrated in blue lines in the figure above. There are two hosts connected to router A and the other to router D. Let's say H1 wishes to transmit H2 a data packet. The packet is sent to router A via H1. The packet is held in router A until it has completed its journey. CRC (cyclic redundancy check) code is used by Router A to verify the checksum. If a CRC error occurs, the packet is rejected; otherwise, it is sent to the next hop; in this case, router F. Router F follows the same procedure and then sends the packet to router D. Finally, the packet is sent to host H2 via router D.
(Also see, Message Switching, Circuit Switching)
Cut-through Switching
Cut-through Switching is a technique of switching data frames or packets in data communications in which the switching device (bridge or switch) sends the frames or packets as soon as the destination address is accessible, rather than waiting for the rest of the data to arrive.

Working Principle
In packet switching systems, cut-through Switching is employed. Packet-switching divides a message into several components called packets, each of which is routed separately from the source to the destination. Because it is a connectionless network switching technology, there is no need to set up a dedicated communication route.
When a data frame or packet arrives at a bridge or switch using cut-through Switching, data transmission may begin as soon as the destination address field is received. The switch checks the destination address against the address table it has stored to see legitimate. If the address is fair and the outgoing connection is accessible, the switching device begins transmitting the frame to the target port immediately, even before the remainder of the frame arrives.
In this case, the switching device serves as a frame forwarder. It cannot run error checks when it begins forwarding since the whole frame is not yet accessible. For error handling, it is dependent on the target devices.
Fragment-Free Switching

Fragment-free Switching is a more sophisticated Cut-through Switching approach.
Fragment-free Switching is a technique for providing error-free transmission by reading at least 64 bytes of a frame before forwarding it to the next node.
Working Principle
It combines the speed for Cut-through Switching with the functionality of error checking. This approach examines the 64 bytes of the ethernet frame that include addressing information. If a collision is found inside the first 64 bytes of a frame, the frame will not be further transmitted.
You can read related articles such as Congestion Control in Computer Networks here.