Understanding Linux Network Internals

Bridges Versus Switches

The terms bridge and switch can be used to refer to the same device. However, nowadays the term bridge is mainly used in the documentation (such as the IEEE specifications referenced at the end of this chapter) that discusses how a bridge behaves and how the STP (which we will see in the next chapter) works. In contrast, references to the actual devices are usually made with the term switch.

The only cases where I have seen people referring to a bridge device using the term bridge is when the device is equipped with only two ports (and bridges with two ports are not that common nowadays). This is why I often define a switch informally as a multiport bridge. Unless you are familiar with the official IEEE documentation, you will probably use the term switch. I personally worked on bridging software for years, and as far as I can remember, I used the term bridge only when working on the documentation, never to refer to a device on any network setup.

Generally speaking, I can say that there is really no difference between a bridge and a switch.

Bridges are pretty common nowadays. You can find bridges with a variable number of ports (and matching prices). An Ethernet bridge, nowadays, represents the most common way to implement a LAN.

With a PC running Linux, you can implement a bridge by installing more than one NIC. You can also find multiport Peripheral Component Interconnect (PCI) NICs on the market that allow you to have more network interfaces than PCI slots. ...