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 UTP: Typically wrapped inside a plastic cover (for mechanical protection).

ØA sample UTP cable with unshielded twisted pairs of wires.

STP: cables are similar to UTP cables except there is a metal foil or braided-metal-mesh.

ØCategory 5(or Se): up to 100 Mbps (common for networks).

Category 6: more twisted than category 5 up to 1 Gbps

ØCoaxial cables: carry signals of higher frequency (100 KHz- 500 KHz) than UTP cables

ØOuter metallic wrapping servers both act as a shield against noise and as the second conductor that completes the circuit.

Fiber-optic cables

ØLight travels at 3*10 elevated to 8 in free space and is the fastest possible speed in the universe.

ØLight slows down in denser media.

ØRefraction occurs at interface with light bending away from the normal when it enters a less dense medium.

ØBeyond the critical angle= total internal reflection.

ØCore and clarity (less dense material).

Elements on a LAN Network:

·Network card: connects computer to network

·Switch: centralizes cabling, being the central node, receiving signal from transmitting work station, redirecting to target station port

·Router: device that forwards data package between networks. It is connected to two or more data lines from different networks

·Hub: receives the data through a port and transmits it to all the other ports.

·Switch: stores MAC addresses for all the devices connected to its ports. When data is receives through a port checks the MAC addressee and  re-directs data to the corresponding port.

·Modem: communication card connected with external network through a port.

·Router: a networking device that forward data packet between computer networks.

SERVER: computer program that provides several services such as sharing resources among clients or performing computation for a client. Sometimes whole computers may be used as servers. A single server can serve multiple clients and a single client can use multiple servers.

·File server computer: computer that stores and manages for multiple users on a network

·Web server computer: computer dedicated to corresponding to requests for web pages

CONNECTING: there are varioustechnologies to connect a home computer to the internet:

1.Modem: converts computer data into an analog audio for transfer over a telephone line, and then a modem in the destination converts it back into data

2.Digital subscriber line (DSL): uses regular copper lines to transfer digital data to and from the phone company’s central office

3.Cable modem: uses the same line that your cable TV signals come in on to transfer the data back and forth

Broadband: connection in which transfer speed is faster than 128 bits per second (DSL and Cable Modems)

SENDING INFORMATION:

·To improve the efficiency of transferring information along a shared network, data is divided into fixed-sized number packets.

·Routers are used to direct packets between networks

PROTOCOL:

·To share information computers need to speak the same language (Communication protocol)

·Set of rules, conventions and data structure that governs the exchange of information over a network.

·Includes guidelines that regulates the following characteristics:

1.access method

2.allowed physical topologies

3.types of cabling

4.speed of data transfer

·Internet Protocol (IP): software deals with the routing of of packets through the maze of interconnected networks to their final destination

·Transmission control protocol (TCP): software breaks the info into packets and delivers it to IP software and then orders the packets at their destination.

IP ADRESS:

Functions:

1.host or network interface identification

2.Location addressing

·Static IP: addresses manually assigned

·Dynamic IP: addresses assigned dynamically on LANs and broadband networks by the Dynamic Host Configuration Protocol

·LAN IP: Gateway address

·WAN IP: Public IP address obtained by ISP provider

DOMAIN NAME SYSTEM (DNS): translates more readly memorized domains names to the numerical IP addresses to locate and identify computer services and devices.

USER DATAGRAM PROTOCOL (UDP):

·Is an alternative to TCP

·The main difference is that TCP is reliable but with a bad performance and UDP is not that reliable but has a better performance

Other protocols build on the foundation established by the TCP/IP protocol suite:

·Simple mail transfer protocol (SMTP)

·File transfer protocol (FTP)

·Telnet

·Hyper text transfer protocol (http)

PROXY or PROXY server: server that acts as an intermediary for requests from clients seeking resources from other servers

FUNCTIONS:

1.Access control

2.Traffic registration

3.Restriction to certain types of traffic

4.Performance improvement

5.Communication anonymity