What is an Ethernet Switch?
Ethernet switching connects wired devices such as computers, laptops, servers, and printers to a local area network (LAN). Multiple Ethernet switch ports allow for faster connectivity and smoother access across many devices at once. First introduced in 1990 and having since dramatically evolved, ethernet switches are the most common form of network switches.
An Ethernet switch creates networks and uses multiple ports to communicate between devices in the LAN. Ethernet switches differ from routers, which connect networks and use only a single LAN and WAN port. A full wired and wireless corporate infrastructure provides wired connectivity and Wi-Fi for wireless connectivity.
Hubs are similar to Ethernet switches in that connected devices on the LAN will be wired to them, using multiple ports. The big difference is that hubs share bandwidth equally among ports, while Ethernet switches can devote more bandwidth to certain ports without degrading network performance. When many devices are active on a network, Ethernet switching provides more robust performance.
Routers connect networks to other networks, most commonly connecting LANs to wide area networks (WANs). Routers are usually placed at the gateway between networks and route data packets along the network.
Most corporate networks use combinations of switches, routers, and hubs, and wired and wireless technology.
What Ethernet Switches Can Do For Your Network
Ethernet switches provide many advantages when correctly installed, integrated, and managed. These include:
- Reduction of network downtime
- Improved network performance and increased available bandwidth on the network
- Relieving strain on individual computing devices
- Protecting the overall corporate network with more robust security
- Lower IT capex and opex costs thanks to remote management and consolidated wiring
- Right-sizing IT infrastructure and planning for future expansion using modular switches
Most corporate networks support a combination of wired and wireless technologies, including Ethernet switching as part of the wired infrastructure. Dozens of devices can connect to a network using an Ethernet switch, and administrators can monitor traffic, control communications among machines, securely manage user access, and rapidly troubleshoot.
The switches come in a wide variety of options, meaning organizations can almost always find a solution right-sized for their network. These range from basic unmanaged network switches offering plug-and-play connectivity, to feature-rich Gigabit Ethernet switches that perform at higher speeds than wireless options.
How Ethernet Switches Work: Terms and Functionality
Frames are sequences of information, travel over Ethernet networks to move data between computers. An Ethernet frame includes a destination address, which is where the data is traveling to, and a source address, which is the location of the device sending the frame. In a standard seven-layer Open Systems Interconnection (OSI) model for computer networking, frames are part of Layer 2, also known as the data-link layer. These are sometimes known as “link layer devices” or “Layer 2 switches.”
Transparent Bridging is the most popular and common form of bridging, crucial to Ethernet switch functionality. Using transparent bridging, a switch automatically begins working without requiring any configuration on a switch or changes to the computers in the network (i.e. the operation of the switch is transparent).
Address Learning -- Ethernet switches control how frames are transmitted between switch ports, making decisions on how traffic is forwarded based on 48-bit media access control (MAC) addresses that are used in LAN standards. An Ethernet switch can learn which devices are on which segments of the network using the source addresses of the frames it receives.
Every port on a switch has a unique MAC address, and as frames are received on ports, the software in the switch looks at the source address and adds it to a table of addresses it constantly updates and maintains. (This is how a switch “discovers” what devices are reachable on which ports.) This table is also known as a forwarding database, which is used by the switch to make decisions on how to filter traffic to reach certain destinations. That the Ethernet switch can “learn” in this manner makes it possible for network administrators to add new connected endpoints to the network without having to manually configure the switch or the endpoints.
Traffic Filtering -- Once a switch has built a database of addresses, it can smoothly select how it filters and forwards traffic. As it learns addresses, a switch checks frames and makes decisions based on the destination address in the frame. Switches can also isolate traffic to only those segments needed to receive frames from senders, ensuring that traffic does not unnecessarily flow to other ports.
Frame Flooding -- Entries in a switch’s forwarding database may drop from the list if the switch doesn’t see any frames from a certain source over a period of time. (This keeps the forwarding database from becoming overloaded with “stale” source information.) If an entry is dropped—meaning it once again is unknown to the switch—but traffic resumes from that entry at a later time, the switch will forward the frame to all switch ports (also known as frame flooding) to search for its correct destination. When it connects to that destination, the switch once again learns the correct port, and frame flooding stops.
Multicast Traffic -- LANs are not only able to transmit frames to single addresses, but also capable of sending frames to multicast addresses, which are received by groups of endpoint destinations. Broadcast addresses are a specific form of multicast address; they group all of the endpoint destinations in the LAN. Multicasts and broadcasts are commonly used for functions such as dynamic address assignment, or sending data in multimedia applications to multiple users on a network at once, such as in online gaming. (Streaming applications such as video, which send high rates of multicast data and generate a lot of traffic, can hog network bandwidth.
Managed vs. Unmanaged Ethernet Switches
Unmanaged Ethernet switching refers to switches that have no user configuration; these can just be plugged in and turned on.
Managed Ethernet switching refers to switches that can be managed and programmed to deliver certain outcomes and perform certain tasks, from adjusting speeds and combining users into subgroups, to monitoring network traffic.