An interconnection device is any device that can enable computers to exchange data on a network. The function of interconnection devices and examples of interconnection devices on networks are explained below:
Network Interface Card (NIC)
A NIC is also known as a network adapter. Any device that wants to communicate and send / receive data must have a NIC installed. They are usually located in a computer’s expansion slot, similar to how you’d see a graphics card or sound card installed. The NIC contains a transceiver which is a combination of a transmitter and receiver. This facilitates data transmission, enabling the device to send and receive data. The NIC also contains a MAC address (also known as a hardware address) which is a unique, 48-bit identifier used by many networking protocols including ethernet and 802.11 wireless. A MAC address looks something like this: 65:85:45:F2:C3:8N
Repeater
Repeaters are non-intelligent network devices that receive a signal through one port. They regenerate that signal and then transmit the signal again on all remaining ports. To extend the length of a network, repeaters can be used to connect network segments (a portion of a computer network) but they can’t be used to connect different networks using different access methods. Repeaters reduce the loss of signal along a cable (known as a attenuation) which in turn provides a more stable connection to the devices connected the repeater. Wireless repeaters are common in many homes and are used to help extend the network coverage to parts of a house which previously had no coverage or very poor signal.
HUB
Hubs are used in Ethernet networks to connect multiple ethernet devices together, forming a network segment (group of computers that is a portion of a network). A hub, like a repeater has no intelligence so simply broadcasts all network data across all ports. However, most hubs can detect basic errors such as collision and because every computer connected to the hub has its own dedicated connection to the hub, this means that if there is a connection failure, it only affects a single device and not the entire hub and all of it’s associated connections / devices.
Bridge
Unlike repeaters, a bridge can extend the capacity as well as the length of a network because each port on a bridge has a MAC address. They are used to connect two or more LANs of the same type, e.g. Ethernet to Ethernet. When activating a bridge on an Ethernet network, they automatically start to capture and analyse addresses of incoming frames, building up a routing table and learning the topology of the network. Because bridges learn about the network, they are considered intelligent devices and can manage traffic, resulting in reduced bandwidth and a more efficient flow of data on a network.
Switch
The switch has replaced a lot of hubs and bridges in Local Area Networks as it’s considered a more intelligent device, improving network performance and reducing the chances of errors occurring on a network. A switch keeps a record of all MAC address connected to it so it can then identify which device is connected to which port. When a frame is received, it then looks at the destination MAC address and knows exactly which port to send the data on to. It doesn’t just send the data out on all ports like a hub does.
Switches also allocate full bandwidth to all ports so if a switch is 10/100Mbps, all ports are allocated 10/100Mbps speed. This is not the case with the a hub where that bandwidth is shared across all ports. They can be used to link a number of end-user devices (e.g. workstations) or they can also interconnect multiple network segments.
Router
If a network has a number of sub-networks (segments) that use different networking protocols and architectures, it requires a sophisticated device to manage the data flow. This device is known as a router which determines how incoming packets get to destination networks in the most efficient way possible. Routers can communicate information about their network with routers on different networks and they store information in a routing table.
Routers are located at the edge of networks (known as gateways) which is the point at which two or more networks connect. For example your home router connects to your ISP. Your home router manages traffic and devices in your home whilst simultaneously talking to your ISP and ensuring data is sent and received efficiently.