Switch

A switch is a device that channels incoming data from any of multiple input ports to a specific output port. It then takes the data and sends it toward its destination. A switch operates at layer 2 or Data Link layer of the OSI model. At layers 2 it looks at each packet, and from the MAC address it determines which device the data unit is intended for. Then with this information the switch sends data it towards the devide's destination.

Layers 2 switching

• Hardware based bridging
• Wire-speed performance
• Collision domain per port
• Traffic containment based on Mac Address

Issues

• No traffic based on Mac address
• Can’t restrict where traffic can go
• No traffic between VLANs
• Unbounded Broadcast domain
• Servers are not centrally located

Bridges

A Bridge is a device that connects two local-area networks (LANs), or two segments of the same LAN. Unlike a router, bridges are protocol independent. They simply forward packets without analyzing and re-routing messages. Bridging occurs at layer 2 of the OSI model which is the data link layer. This means a bridge cannot read IP addresses, but only the outermost hardware address of a packet.