Ethernet Hub Repeats Everything It Hears

As seen in the figure, Larry sends data to the hub, and the hub repeats what Larry sent out the cables to Archie and Bob. It's that simple!

Figure 4-11 shows cabling, but it does not show which pairs of wires are used. Interestingly, the hub expects straight-though Ethernet cabling between itself and the PCs. Why is that? Well, the people who make hubs, knowing that Ethernet NICs in PCs send on the twisted pair that uses pins 1 and 2 and receive on twisted pair that uses pins 3 and 6, do the opposite. Therefore, a straight-through cable works between a PC NIC and a hub. Figure 4-12 illustrates the concept.