Layer 2 Switch Functions

CE

Layer 2 switches are network devices that operate at the Data Link layer of the OSI model. Their primary function is to forward data frames within a LAN or VLAN, based on the MAC addresses of the devices connected to them.

The correct answers to this question are C and E.

C. Moves packets within a VLAN: Layer 2 switches create broadcast domains and reduce network congestion by forwarding traffic only to the devices that require it. They use MAC addresses to learn the physical location of devices on the network and use that information to forward frames only to the correct ports. This helps to prevent unnecessary broadcast traffic, which can consume bandwidth and slow down the network.

D. Moves packets between different VLANs: This is not a function of a Layer 2 switch. Inter-VLAN communication requires a Layer 3 device, such as a router, to forward packets between different VLANs.

E. Makes forwarding decisions based on the MAC address of a packet: This is a key function of Layer 2 switches. When a switch receives a data frame, it examines the destination MAC address in the frame header and uses its MAC address table to determine which port to forward the frame out of. The switch learns MAC addresses by examining the source MAC address of frames received on each port and associating them with the port. This process is known as MAC address learning.

A. Acts as a central point for association and authentication servers: This is not a function of a Layer 2 switch. Authentication servers are typically located at the network perimeter and are used to authenticate users before allowing them access to network resources.

B. Selects the best route between networks on a WAN: This is not a function of a Layer 2 switch. WAN routers are responsible for selecting the best path between different networks based on metrics such as bandwidth, delay, and cost.