Network devices or networking hardware are the physical devices that are used for establishing connections and facilating interaction between different devices in a computer network.
Hubs work in the physical layer of the OSI model. A hub is a device for connecting multiple Ethernet devices and making them act as a single network segment. It has multiple inputs and output ports in which a signal introduced at the input of any port appears at the output of every port except the original incoming port.
A hub can be used with both digital and analog data. Hubs do not perform packet filtering or addressing function, they send the data packets to all the connected devices.
A repeater operates at the physical layer of the OSI model.
A bridge operates at the data link layer of the OSI model. It can read only the outmost hardware address of the packet but cannot read the IP address. It reads the outmost section of the data packet to tell where the message is going. It reduces the traffic on other network segments. It does not send all the packets. So, a bridge can be programmed to reject packets from a particular network.
Switches may operate at one or more layers of the OSI model. They may operate in the data link layer and network layer; a device that operates simultaneously at more than one of these layers is known as a multilayer switch.
A Switch can check the errors before forwarding the data, which makes it more efficient and improves its performance. A switch is the better version of a hub. It is a multi-port bridge device.
Routers are small physical devices that operate at the network layer to join multiple networks together.
A gateway is an internetworking capable of joining together two networks that use different base protocols.
A network gateway can be implemented completely in software, hardware, or a combination of both, depending on the types of protocols they support.
A network gateway can operate at any level of the OSI model. A broadband router typically serves as the network gateway, although ordinary computers can also be configured to perform equivalent functions.
A brouter is a combination of a Bridge and a Router. It provides the functions of a bridge and a router, so it can operate at the data link and network layers of the OSI Model.
Most brouters are simply routers that have been configured. The main function of a bridge is to connect two different LAN segments using the same protocol. A router, on the other hand, is used to route the packets in a network.