F5 GLOSSARY

Switch

What is a Switch?

A switch is a device that relays data within a network. Switches are categorized by the protocol layer they operate at. Typically, when simply referred to as a "switch," it usually points to either:

  • L2 Switches (Layer 2 Switches): Operate at the data link layer (e.g., Ethernet).
  • L3 Switches (Layer 3 Switches): Operate at the network layer (e.g., IP).

L2 Switches:
L2 switches associate Ethernet MAC addresses with specific ports on the switch. Based on this information, the switch forwards incoming data frames to the port associated with the destination MAC address. These switches are also commonly referred to as LAN switches.

L3 Switches:
L3 switches forward data packets based on IP addresses. Equipped with routing capabilities, they can forward packets between networks, much like routers. Many L3 switch products also support VLAN technology, which allows a single physical L2 switch to function as multiple virtual L2 switches. For communication between these virtual L2 switches, L3 switches perform routing, making internal L3 switch functionality common in VLAN-compatible (especially core) switches.

Other types of switches include:

  • L4 Switches (Layer 4 Switches): Operate at the transport layer (e.g., TCP).
  • L7 Switches (Layer 7 Switches): Cover up to the application layer (e.g., HTTP).

L4 and L7 switches can perform advanced packet forwarding based on TCP headers or application-level data. These capabilities enable load balancing, bandwidth control, session optimization, WAN acceleration, and enhanced security. Since these switches don’t just relay packets but also provide advanced traffic control and delivery features, they are collectively referred to as ADC (Application Delivery Controllers).

F5 offers F5 BIG-IP, which includes ADC capabilities, providing features like load balancing, advanced traffic management, and security enhancements.