Introduction to Network

Computer Networks Primary purposes of network is to increase productivity. The minimum requirements for setting up a network are: An NIC card Network Media Connectors

Network Interface Circuit (NIC) Card IS a printed circuit board that provides network communication capabilities to and from a PC. Amplifies electronic signals Package data for transmission Physically connects computer to transmission media Each NIC card is stored with a unique address provided by IEEE called MAC address. MAC is a 48 bit address, the first 24 bits is the vendor code and the next 24 bits represent the Serial Number.

Network Media IS the actual physical environment which data travels as it moves from one computer to another, and it connects network devices. The most common types of network media are: Coaxial Cables Twisted Pair Cables Fiber Optic Cables Wireless

Coaxial Cables Consists of Used to connect dish antenna to a TV set. Single copper conductor Plastic insulation Over a wire mesh( Braided Copper Shielding) Another plastic insulation. Used to connect dish antenna to a TV set. Coaxial Cables are of two types: Thicknet (longest distance ) Thinnet Connectors used: BNC T Terminators.

Twisted Pair Cables Used for both LANs and telephone systems. Composed of four color-coded pairs of copper conductors twisted around each other. The outer jacket provides protection and keeps the pairs in alignment. There are two types: Unshielded Twisted Pair Cable (UTP) Shielded Twisted Pair Cable (STP)

Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) Used in normal office environments. IS the most popular network media. Connectors used is RJ 45 connectors.

Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) The advantage of UTP is its ability to limit signal degradation from electromagnetic interference (EMI) and Radio frequency interference. Reduces Crosstalk There are different categories of UTP cable. The most used is CAT5 –have the maximum segment length 100m.(shorter than coax)

Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) Implementation Straight through Cable Used for Switch to router Switch to PC or server Hub to PC or server

Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) Implementation Crossover Cable (pins 1 and 2 on one connector connect to pins 3 and 6 on the other) Used for Switch to switch Switch to hub Hub to hub Router to router PC to PC

Twisted Pair Cables Unshielded Twisted Pair Cable (UTP) Implementation Roll-over Cable (pins 1 on one connector connect to pins 8 on the other) Used for Console port of a router or switch to the PC

Twisted Pair Cables shielded Twisted Pair Cable (STP) Protect against signal degradation. Each pair of wires is wrapped in a metallic foil. The four pairs of wires are then wrapped in an overall metallic braid or foil.

Twisted Pair Cables shielded Twisted Pair Cable (STP) Reduces electrical noise within and outside the cable. Used in Token Ring. Maximum segment length is 100m

Fiber Optic Cables Capable of conducting modulated light transmission. Consists of two fibers encased in separate sheaths. A cable, consisting of a center glass core surrounded by layers of plastic, that transmits data using light rather than electricity. Connectors used are multimode. Not effected by EMI There are two types of fiber-optic cables: Single-mode Multimode

Fiber Optic Cables Single-mode Allow only one mode of light to propagate through the fiber. Capable of higher bandwidth and greater distances Uses Lasers as the light-generation method and is expensive.

Fiber Optic Cables Multimode Allows multiple modes of light to propagate through the fiber. Often used for workgroup applications. The segment length is less than the single-mode.

Wireless The device use to signal distribution called wireless hub or access point To receive the signal from the access point the pc needs to install wireless (NIC) Radio frequency (RF) Transmit voice, video and data Affected by electromagnetic interference Limited distance Wireless LAN (WLAN) use radio waves, microwave and Infrared waves.

Network Topologies The configurations of network components Widely used network topologies Bus Star Extended star Ring Mesh Partial Mesh

Bus Network Topology Most simple network topology All devices connected to a common central cable (wire or other media ) Inexpensive Easily expanded If cable fails, the entire network will shut down Earlier Ethernet commonly implement a bus topology

Bus Network Topology (Continued)

Star Network Topology Star topology is centered around central routing device called a switch or a hub by point-to-point links. All network nodes connect to the hub Easy to install and update If hub fails, network fails Disadvantage that it require more cabling therefore, higher cost than the bus. Extended star

Ring Network Topology Each node connected to two other nodes in a ring Similar to the buss, but with the ends of the buss connected together by unidirectional transmission link to form a single closed loop. Each station on the network connects to the network at a repeater. Expensive and difficult to install One example of a ring topology is Token Ring networks

Ring Network Topology (Continued)

Dual-Ring Tow rings allow data to be sent in both directions Creates redundancy.

Mesh Network Topology Every node connected to every other node Fast Reliable No hub or bus to fail If one device goes down, it is the only node affected Expensive Every node must be wired to every other node Difficult to add nodes If there are 32 nodes in a mesh network and you wish to add a new node, how many new cables must you add? 32 nodes Add new 33rd node New node must connect to all 32 existing nodes, therefore 32 cables to add

Partial Mesh At least one derive is connected to all other devices without being fully meshed.