However, note that “switch” is a generic term for network devices that may function as bridges, or routers, or even both, depending on their feature sets and configuration. We will use the words “bridge” and “switch” interchangeably to describe Ethernet bridges.
As a result, modern Ethernet networks may consist of hundreds of switch connections in a building, and thousands of switch connections across a campus network.
Modern buildings have multiple wireless access points (APs) to provide 802.11 Wi-Fi services for things like smartphones and tablets, and each of the APs is also connected to a cabled Ethernet system. Every VoIP telephone and every printer is a computer, and even building management systems and access controls (door locks) are networked. Over the years, computers have become ubiquitous, and many people use multiple devices at their jobs, including their laptops, smartphones, and tablets. Things have changed quite a lot since Ethernet bridges were first developed in the early 1980s. Later, when twisted-pair Ethernet was developed and switches with many ports became widely available, they were often used as the central connection point, or hub, of Ethernet cabling systems, resulting in the name “switching hub.” Today, in the marketplace, these devices are simply called switches. At that time, Ethernet only supported connections to coaxial cables. The first Ethernet bridges were two-port devices that could link two of the original Ethernet system’s coaxial cable segments together. That’s the result of lots of hard work on the part of the standards engineers to define a set of standards that vendors could agree upon and implement in their switch designs. The standardization of bridging operations in switches makes it possible to buy switches from different vendors that will work together when combined in a network design. Ethernet bridging was initially defined in the 802.1D IEEE Standard for Local and Metropolitan Area Networks: Media Access Control (MAC) Bridges. To do this, they copy Ethernet frames from one switch port to another, based on the Media Access Control (MAC) addresses in the Ethernet frames. By moving Ethernet frames between the switch ports, a switch links the traffic carried by the individual network connections into a larger Ethernet network.Įthernet switches perform their linking function by bridging Ethernet frames between Ethernet segments. Ethernet switches link Ethernet devices together by relaying Ethernet frames between the devices connected to the switches.