Question

Discuss at least three devices and the network media that is used within your home network or your organization's network. Explain in detail!

Answer 1

NETWORK DEVICES:

1) HUB:

Hubs connect multiple computer networking devices together. A hub also acts as a repeater in that it amplifies signals that deteriorate after traveling long distances over connecting cables. A hub is the simplest in the family of network connecting devices because it connects LAN components with identical protocols.

A hub can be used with both digital and analog data, provided its settings have been configured to prepare for the formatting of the incoming data. For example, if the incoming data is in digital format, the hub must pass it on as packets; however, if the incoming data is analog, then the hub passes it on in signal form.

Hubs do not perform packet filtering or addressing functions; they just send data packets to all connected devices. Hubs operate at the Physical layer of the Open Systems Interconnection (OSI) model. There are two types of hubs: simple and multiple port.

2)SWITCH:

Switches generally have a more intelligent role than hubs. A switch is a multi-port device that improves network efficiency. The switch maintains limited routing information about nodes in the internal network, and it allows connections to systems like hubs or routers. Strands of LANs are usually connected using switches. Generally, switches can read the hardware addresses of incoming packets to transmit them to the appropriate destination.

Using switches improves network efficiency over hubs or routers because of the virtual circuit capability. Switches also improve network security because the virtual circuits are more difficult to examine with network monitors. You can think of a switch as a device that has some of the best capabilities of routers and hubs combined. A switch can work at either the Data Link layer or the Network layer of the OSI model. A multilayer switch is one that can operate at both layers, which means that it can operate as both a switch and a router. A multilayer switch is a high-performance device that supports the same routing protocols as routers.

Switches can be subject to distributed denial of service (DDoS) attacks; flood guards are used to prevent malicious traffic from bringing the switch to a halt. Switch port security is important so be sure to secure switches: Disable all unused ports and use DHCP snooping, ARP inspection and MAC address filtering.

3)ROUTER:

Routers help transmit packets to their destinations by charting a path through the sea of interconnected networking devices using different network topologies. Routers are intelligent devices, and they store information about the networks they’re connected to. Most routers can be configured to operate as packet-filtering firewalls and use access control lists (ACLs). Routers, in conjunction with a channel service unit/data service unit (CSU/DSU), are also used to translate from LAN framing to WAN framing. This is needed because LANs and WANs use different network protocols. Such routers are known as border routers. They serve as the outside connection of a LAN to a WAN, and they operate at the border of your network.

Router are also used to divide internal networks into two or more subnetworks. Routers can also be connected internally to other routers, creating zones that operate independently. Routers establish communication by maintaining tables about destinations and local connections. A router contains information about the systems connected to it and where to send requests if the destination isn’t known. Routers usually communicate routing and other information using one of three standard protocols: Routing Information Protocol (RIP), Border Gateway Protocol (BGP) or Open Shortest Path First (OSPF).

Routers are your first line of defence, and they must be configured to pass only traffic that is authorised by network administrators. The routes themselves can be configured as static or dynamic. If they are static, they can only be configured manually and stay that way until changed. If they are dynamic, they learn of other routers around them and use information about those routers to build their routing tables.

Routers are general-purpose devices that interconnect two or more heterogeneous networks. They are usually dedicated to special-purpose computers, with separate input and output network interfaces for each connected network. Because routers and gateways are the backbone of large computer networks like the internet, they have special features that give them the flexibility and the ability to cope with varying network addressing schemes and frame sizes through segmentation of big packets into smaller sizes that fit the new network components. Each router interface has its own Address Resolution Protocol (ARP) module, its own LAN address (network card address) and its own Internet Protocol (IP) address. The router, with the help of a routing table, has knowledge of routes a packet could take from its source to its destination. The routing table, like in the bridge and switch, grows dynamically. Upon receipt of a packet, the router removes the packet headers and trailers and analyses the IP header by determining the source and destination addresses and data type, and noting the arrival time. It also updates the router table with new addresses not already in the table. The IP header and arrival time information is entered in the routing table. Routers normally work at the Network layer of the OSI model.

NETWORK MEDIA:

1)COAXIAL CABLES:

Coaxial cable uses a single conductor in the middle of a cable. The central conductor is surrounded by an insulator called the dielectric. A conductive shield is put around the dielectric. This shield acts as the second conductor for the circuit as well serves to protect the inner conductor from interference. Coaxial cable for local area network (LAN) connections is obsolete. Coaxial cable is being used in some cases for delivering the last mile of service. For e.g., coaxial cables are being used by Cable TV networks to deliver high-speed service customer premises.

2) TWISTED PAIR CABLES:

There are two types of twisted pair cables:

a)Unshielded Twisted Pair Cables:

Unshielded twisted pair cabling, or UTP cabling, is the most common type of network cabling. It consists of four twisted pairs of wire, each with a different number of twists per foot, all encased on one sheath. UTP cabling is graded according to category. Category 3 and 4 were replaced by Category 5 cabling by the year 2000. Category 5 is recommended for running Ethernet at speeds of 100 Mbps. Category 5e, was introduced to run gigabit Ethernet or 1000BaseT networks. Category 6 and Category 6a have since been introduced to give better performance at higher speeds. UTP cabling has an intrinsic impedance of 100 ohms.

b)Shielded Twisted Pair Cables:

There are two types of shielded twisted pair wiring. In the 1980s and 1990s shielded twisted pair was promoted as the best wire type for Token Ring networks. This had an intrinsic impedance of 150 ohms. A new wiring trend is to use 100 ohm shielded twisted pair. The shielding reduces noise and increases the performance of the cable. These are sometimes called foiled twisted pair, or FTP (not to be confused with file transfer protocol) or sometimes called screened twisted pair, or ScTP. These types of cables are compatible with normal UTP.

3) FIBER OPTIC CABLES:

There are two types of Fiber optic cables:

a)Multi Mode Fiber Optic Cables:

Fiber optic cable is sometimes called wave guide or light guide because it guides the light waves along the length of the cable.Multi mode fiber is used for short cable runs, usually 1.6 mi (approximately 2 km) or less.

b)Single Mode Fiber Optic Cables:

Single mode fiber optic cable can operate over much longer distances. Because the fiber only allows one mode of light to propagate, light pulses put on the fiber keep their shape much longer. This allows the light pulses to travel much further without interfering with other pulses. Single mode fibre is recommended for cable runs in excess of 1.6 mi.