Which switching technique minimizes latency but may forward bad frames, requiring retransmission?

Which switching technique minimizes latency but may forward bad frames, requiring retransmission?

• A. Fragment-free
• B. Store-and-forward
• C. Circuit-switching
• D. Cut-through

Answer: (D)

Minimizing forwarding latency in a switch comes from starting to send a frame as soon as enough header information is read, without waiting for the whole frame. This is cut-through switching. It reads the destination address and immediately forwards the frame, so the initial delay is kept very low. The trade-off is that error checking isn’t completed before forwarding, so a corrupted frame can be passed along and later cause a retransmission. That trade-off is what makes it the fastest option, but the risk of forwarding bad frames is real. For comparison, store-and-forward waits until the entire frame is received and passes a CRC check before forwarding, which eliminates bad frames but adds latency. Fragment-free is a middle ground, forwarding after the first portion of the frame, which reduces some risk while keeping latency lower than store-and-forward, but not as low as pure cut-through.

Minimizing forwarding latency in a switch comes from starting to send a frame as soon as enough header information is read, without waiting for the whole frame. This is cut-through switching. It reads the destination address and immediately forwards the frame, so the initial delay is kept very low. The trade-off is that error checking isn’t completed before forwarding, so a corrupted frame can be passed along and later cause a retransmission. That trade-off is what makes it the fastest option, but the risk of forwarding bad frames is real. For comparison, store-and-forward waits until the entire frame is received and passes a CRC check before forwarding, which eliminates bad frames but adds latency. Fragment-free is a middle ground, forwarding after the first portion of the frame, which reduces some risk while keeping latency lower than store-and-forward, but not as low as pure cut-through.