Problem:
What switching modes exist and what are the differences?
 

Solution:
Cut-through packet switching (CT)

Packet switching approach that streams data through a switch so that the leading edge of a packet exits the switch at the output port before the packet finishes entering the input port. A device using cut-through packet switching reads, processes, and forwards packets as soon as the destination address is looked up and the outgoing port determined. Also known as on-the-fly packet switching. Compare with store and forward packet switching.

Pros: Faster, more efficient
Cons: Will forward broken frames and possibly amplify network problems


Store and forward packet switching (S&F)

Packet-switching technique in which frames are completely processed before being forwarded out the appropriate port. This processing includes calculating the CRC and checking the destination address. In addition, frames must be temporarily stored until network resources (such as an unused link) are available to forward the message. Contrast with cut-through packet switching.

Pros: More reliable, will filter away broken frames
Cons: Slower, higher CPU/RAM load on the switch


Adaptive cut-through packet switching (A-CT)
A forwarding switch cut-through technology that adapts its data forwarding process (Cut-through, Fragment-Free, Store & Forward) according to the data error rate within the network. Attempts to detect broken frames as they pass through and alternate between switching modes when necessary.

Pros: Same as cut-through
Cons: May cause problems tracking down faulty equipment


Fragment-free packet switching (FgFree)
A type of forwarding method used in switches that allows data to be forwarded through after the first 64bytes of each data packet is checked due to the data error rate condition of the network. In effect, this is an attempt to work-around network problems by filtering out bad traffic.

Pros: Same as cut-through in error-free environment
Cons: Will not actually discriminate between faulty and OK packets