Network Devices

A router is an Open Systems Interconnect (OSI) model Layer 3 device. IP addressing and routing is performed at Layer 3. A router is used to connect networks that are assigned IP addresses in different subnets. A router delimits a broadcast domain.

A bridge is a Layer 2 device that connects network segments. A bridge is more efficient than a repeater because it can analyze traffic. However, it does not limit a broadcast domain.

A firewall is a security device that filters traffic. Basic firewalls filter incoming and outgoing traffic based on the TCP/IP port. A firewall is typically used between segments that have different security requirements. There are different types of firewalls that operate at different layers of the OSI model. For example, a packet filter firewall operates at the Layer 3 of the OSI model, but an application layer firewall operates at Layer 7.

A repeater also connects network segments. However, a repeater simply rebroadcasts the signal. It cannot be used to connect segments in different IP subnets. A repeater also does not serve as a broadcast domain delimiter. A repeater operates at Layer 1 of the OSI model.