Layer 2 Switch Functions

CE.

Layer 2 switches operate at the Data Link Layer (Layer 2) of the OSI model, and their primary function is to forward frames between network devices on the same VLAN. They achieve this by examining the Media Access Control (MAC) address of incoming frames and forwarding them only to the port that leads to the destination device.

The two functions of a Layer 2 switch are:

1. Moving packets within a VLAN: A VLAN (Virtual Local Area Network) is a logical group of devices that are not necessarily located on the same physical network segment but are configured to communicate as if they were. Layer 2 switches allow devices on the same VLAN to communicate with each other by forwarding frames between the ports that are members of the same VLAN. This is achieved by associating each port on the switch with a specific VLAN.

2. Making forwarding decisions based on the MAC address of a packet: Layer 2 switches use the MAC address of incoming frames to make forwarding decisions. They maintain a MAC address table that maps each MAC address to the port on which the associated device is connected. When a frame arrives, the switch checks the destination MAC address against its MAC address table and forwards the frame only to the port that leads to the destination device. If the switch does not have an entry for the MAC address, it broadcasts the frame to all ports on the same VLAN.

Option A is incorrect because switches do not perform association or authentication functions. These are typically handled by servers such as RADIUS or TACACS+ servers.

Option B is incorrect because switches do not make routing decisions between networks on a WAN. This function is performed by Layer 3 devices such as routers.

Option D is partially correct in that some Layer 3 switches can move packets between different VLANs, but standard Layer 2 switches do not have this capability.

Therefore, the correct answers are options C and E.