In cut-through switching, the switch forwards the data almost immediately. It just needs to know the source and destination MAC addresses. As soon as it has this information, it will forward the data, even if the whole frame hasn't been received by the switch. A simplified visualization of this can be seen in the following diagram:
Figure 6.2: Cut-through switching
Let's go through the numbered steps in the preceding diagram so that we can understand this process better:
- In step 1, the frame is being sent.
- In step 2, the switch receives the destination MAC address.
- In step 3, the switch starts to forward the frame, ...
