1. Network Repeater
Network repeaters regenerate incoming electrical, wireless or optical signals. With physical media like Ethernet or Wi-Fi, data transmissions can only span a limited distance before the quality of the signal degrades. Repeaters attempt to preserve signal integrity and extend the distance over which data can safely travel. Actual network devices that serve as repeaters usually have some other name. Active hubs, for example, are repeaters. Active hubs are sometimes also called Multiport Repeaters but more commonly they are just “hubs.” Other types of passive hubs are not repeaters. In Wi-Fi, access points function as repeaters only when operating in so-called Repeater mode .
2. Network Hub
A hub is a small Network Device. A hub joins multiple computers (or other network devices) together to form a single network segment. On this network segment, all computers can communicate directly with each other. Ethernet hubs are by far the most common type, but hubs for other types of networks such as USB also exist. A hub includes a series of ports that each accept a network cable, one port is reserved for “uplink” connections to another hub or similar device.
3. Network Bridge
It reads the outermost section of data on the data packet, to tell where the message is going only the outermost hardware address of the packet. It reduces the traffic on other network segments,since it does not send all packets. Bridges can be programmed to reject packets from particular networks Bridging occurs at the data link layer of the OSI model. Bridge cannot read IP addresses. Bridge can read the ethernet data which gives the hardware address of the destination address. Bridges forward all broadcast messages.
4. Network Router
It is a network device with interfaces in multiple networks whose task is to copy packets from one network to another. Router gives path to data packet to destination. Routers provide connectivity inside enterprises, between enterprises and the Internet, and within an Internet Service Provider (ISP). It operates at Layer 3 (Network Layer) of the OSI Model. Router works with Static Routing manually configure by Network Administrator. Router works with Dynamic Routing which routers calculate automatically by different methods. Router stores calculate path in his Routing Table. The network router will then use its routing table to make intelligent decisions about which packets to copy to which of its interfaces. The router will use this information to create a routing table. This process is known as routing.
5. Network Switch
Network Switch is a small hardware device that joins multiple computers together within one local area network (LAN).
Network Switches operate at layer two (Data Link Layer) of the OSI model . Network switches appear nearly identical to network hubs, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Unlike hubs, Switches are capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately. By delivering messages only to the connected device intended. Switch conserves network bandwidth and offers generally better performance than a hub. Switch supports different bandwidth either 10/100 Mbps Fast Ethernet or Gigabit Ethernet (10/100/1000) standards.
A gateway is an interconnecting device which joins two different network together they are also known as protocol converters. It accepts packet formed for one protocol and converts the formated packet into another protocol.
7. CSU/DSU (Channel Service Unit/Data Service Unit)
CSU/DSU is a hardware device about the size of an external modem that converts a digital data frame from the communications technology used on a local area network (LAN) into a frame appropriate to a wide-area network (WAN) and vice versa. The Channel Service Unit (CSU) receives and transmits signals from and to the WAN line and provides a barrier for electrical interference from either side of the unit. The CSU can also echo loop back signals from the phone company for testing purposes. The Data Service Unit (DSU) manages line control,and converts input and output between RS-232 C, RS-449, or V.xx frames from the LAN and the time-division multiplexed (TDM) DSX frames on the T-1 line.The DSU manages timing errors and signal regeneration.The DSU provides a modem-like interface between the computer as Data Terminal Equipment(DTE) and the CSU.
Modem is a device that converts digital signal to analog signal (modulator) at the sender’s end and converts back analog signal to digital signal (demodulator) at the receiver’s end. A modem is always placed between a telephone line and a computer. A modem links home network to the Internet through Internet Service Provider (ISP). The high speed types of data outside your home aren’t suitable for your direct use, so modems convert the data into digital Ethernet, which all the network equipment in your home can use. The internet services that are outside your home (or business) which are supplied by your ISP are either DSL, cable, dial-up, or satellite. Modems are often combined with a router into a single unit, which then also gives you a firewall protecting of your network from attack. If your modem is not also a router, then you will probably want a router in addition to your modem.
9. Ethernet Card
An Ethernet card is one kind of network adapter. These adapters support the Ethernet standard for high-speed network connections via cables. Ethernet cards are sometimes known as network interface cards (NICs).