A LAN Switch Reduce Data Packet Collision

A LAN switch is device that reduce data packet collision, and increase transmission speed. Switch establishes a connection between two pc s so when we want to send packets to pc 2 the switch save the address in temporary memory called (buffer) reading the Mac address and compare it with a list of addresses in look up table .

switch methods:

switch uses one of three ways:Cut-through :when switch receives the packet it start to save 6 bytes that shows the address information and start to send it. even though the packet is not fully send to switch.Store and forward :that means switch save the whole packets and check the packets for an error if there are the packet not send if not the switch compare the Mac address with addresses in look up table .Fragment-free :like cut-through which is saving the 64 bytes before sending the packets because error and collision happens during these initial 64bytes.

Switching type:

Shared-memory: The switch saves all packets in a memory buffer that share all the switch ports. Then, the switch sends the packets from correct port to the destination node.Matrix: has internal grid which the input ports and the output ports cross each other. When the switch receive a packet on the input port, the switch check the MAC address in the lookup table to find the right output port. The two port then are intersect.Bus-architecture: has internal transmission path using time division multiplexer access to shared all ports. to dedicates a memory buffer to each port.C:UsersacerDesktoplayer2switches1.pnghttp://www.tech-faq.com/lan-switches. htm

Router:

Router is hardware device use to send information to another computer or system.How it works? when you want to send an e-mail to another computer that is not in the same local network .i.e.( any computer that is not on same Ethernet network). To which we call default router or "gateway" This router contains all the packages with different destination addresses to the computer network of origin.In fact . router is a very fast computer. It has a processor, memory, software and inputs outputs connection to communicate with other computers.To keep things simple we will take router with minimal connections required.

This would be an Ethernet port and port WAN (Wide Area Network). The computer you want to send an e-mail to Needs to be connect to Ethernet interface. This e-mail will be redirected by the WAN interface to WAN port on the destination (router),since each destination add is saved individually in the memory of the routerhttp://www.webopedia.com/TERM/R/router.htmlress

Requirement:

In restaurant network we need router to connect local network to any network that manager can see the work remotely.C:UsersacerDesktopdlink-DES-1008E-networksetup-600.jpg

What is Modem:

To understand the modem take this example when you want to send information(video e-mail) along telephone line you need modem. Why? because computer understand digital information and the signal transmitted along telephone line is analog. So the modem convert between them for that it's short for modulate demodulate.

Types of modem:

External modem.: have own power supply ,connect with a computer's serial port. By cable and socket for telephone line connection and Because it has own power supply, you can turn off the modem to break an online connection. Also does not drain any power from the computer unlike internal modem and you can see modems connection activity by watching lights.Internal modem: comes inside computer system.

Activated when run a communications program and turned off when exit the program.

How it works:

When modem first connect to telephone line you will hear screeching sound these digital signals being modulated into analog signal. higher tone represent the digit 1and a lower tone represent the digit 0. The receiving modem demodulate signal into digital and sends them to the receiving computer. The modems can tell incoming from the outgoing data signals by the type of tones they use. also allows to compress digitalsignals before modulating them and decompressing them after demodulating the signals. This make data travel more efficient.To establish a speed network in restaurant we have to balance the data flow through cable with speed of network devices .so we decided to connect the network to desktop server with speed 10100Mbps Ethernet ,switch 8 ports10 /100 mbps speed