Before the Ethernet Switch was developed, data networks comprised coaxial cable, repeaters and early hubs. Modern Ethernet switches often operate at 10, 100 and 1000Mbps and can automatically switch between these speeds depending on the capabilities of the end user devices. This give flexibility to owners and administrators of networks when upgrading workstations, peripherals and servers.
Hubs relied upon building a ‘shared environment’ where all end user devices had equal rights when it came to transmitting data within the network. The Ethernet technology was built upon something known as CSMA/CD (Carrier Sensed Multiple Access with Collision Detect). As a device, a hub is a fairly unintelligent device that merely accepts data on a single port and floods that data out of the remaining ports in an attempt to ensure the intended end user workstation receives the specific data addressed to it. The problem is that all other workstations attached to the hub also receive the same data.
Ethernet switches were designed to make the data network more efficient by ensuring that only the intended recipient actually receives the specific data. In order to achieve this, an Ethernet switch had to have more intelligence and the ability to seek out an individual end user device to which to switch the data. All network devices will have a unique 48-bit MAC Address ‘burnt in’ to the network interface which becomes that device’s unique identity on the network.
The switch employs a method of address learning to harvest all the MAC Addresses of physically attached devices and maintain a table of addresses and to which physical port they are attached. This enables the Ethernet switch to make specific decision as to which port to forward data out in order to reach the intended recipient of the data.
Modern Ethernet switches perform many functions, but the fundamental functions include:
Filtering and Forwarding
These functions will be described in more detail in future posts. At Network Systems Training (UK) Ltd, we run a number of training courses designed to teach delegates how to install, operate and manage a variety of Ethernet Switches. A lot of our training courses incorporate the use of Ethernet switches for the delivery of Intranet and Internet data. Please take a look at our training course schedule if you think you may need professional data network training that that involves the use of Ethernet devices.
Keep a lookout for further posts providing technical descriptions of how Layer 2 and Layer 3 Ethernet Switches operate as well as technical briefs on features incorporated within Ethernet Switches.
For a comprehensive look at Ethernet Technology, take a look at our course schedule where you will see dates published for our 4-Day The Evolution of Ethernet training course.