INTERNET INFRASTRUCTURE

LANS WANS INTRANETS AND EXTRANETS WIRELESS NETWORKS

It uses radio waves to connect computers equipped with wireless NICs. While there are a number of different wireless standards in use, most wireless hardware available today supports one or more of the IEEE series of specifications. IEEE networks are often referred to as wireless fidelity (wi-fi) Wireless networking can be used to connect computers directly to each other in a peer-to-peer network, or to connect computers to an access point that can be used to connect to a wireless LAN or even the internet. Wireless networks use radio waves to network computers

What are the advantages? Older buildings may make it impossible or very expensive to set up network connections using cable. Wireless technology can penetrate walls and make such networking straightforward and affordable Computers and other equipment in a network can be rearranged without the need to move or change cable connections.

Internet Backbone Internet backbone consists of high-speed lines that form the core network of the internet. The first Internet backbones were supported by ARPANET and later NSFnet. A number of different companies currently support the links that make up the internet backbone. Internet backbone high-speed lines include T1,T3,OC-1, and OC-3 cables.

Internet Backbone T1 cables contain two twisted-pair wires with a bandwidth of megabits per second. T3 lines contain 28T1 lines and have a bandwidth of Mbps. OC-1 and OC-3 are fibre optic cables (optical carrier or OC) and support capacities of 51.84Mbps and Mbps

Bandwidth, Throughput, and Latency Bandwidth expresses the theoretical maximum amount of data that an internet connection can transmit in one second. Internet bandwidth is measured in bits per second E.gs. Of Bandwidths

Bandwidth Bandwidth can be symmetrical (even) or asymmetrical (uneven) depending on the technology used to connect to the internet Technologies offering the same bandwidth speeds whether uploading or downloading data are symmetrical Technologies with differing bandwidths for uploading and downloading are referred to as asymmetrical

Bandwidth Asymmetrical technologies almost always make more bandwidth available for downloading compared to uploading. This uneven division is a compromise that meets the needs of most internet users because most people download data far more frequently than they upload it. It is important to realize that bandwidth measures the capacity of an internet connection, stating only the maximum theoretical data transmission capacity of the connecting medium

Bandwidth Network overhead typically prevents a connection from achieving its theoretical maximum. Network over head means that the network itself uses a certain percentage of available bandwidth to support data transmission. E.g. TCP/IP protocol requires some bandwidth when packaging and addressing data.

Throughput It provides a better measure of internet connection speed than bandwidth. Throughput rates the actual amount of user data the network can transmit per second, rather than the theoretical rate of data transmission capacity measured by bandwidth. Throughput measures only useable data transmitted and does not include data used for network overhead.

Latency Even an internet connection with high bandwidth and/or high throughput could be slow due to latency. Latency refers to the time between the transmission and reception of data across a network. It is expressed as milliseconds (ms)

Latency A number of factors contribute to the delays caused by latency, including device delays and network congestion Although the bandwidth and throughput for a Satellite internet connections may be high, the long route that the satellite signals must travel between earth and outer space can cause delays (latency) of more than 750 ms. A user can check latency using a utility program called ping.

Latency Ping sends a small data packet to a host and then measures the time it takes for the packet to go to the host and return.

Connection TypeLatency Rate Dial-up modem ms ISDN15-30ms DSL/Cable10-20ms Satellite ms T12-5ms

Exercise Ping

ISPs How to choose an ISP – Needs assessment: how you use the internet whether is for checking of mails or beyond that. If you use the internet to check mails and browse the internet, you don’t need an ISP who offers large amount of bandwidth but if you view streaming video, upload or download large files, or play online games, then you need an ISP who offers large amount of bandwidth

ISP Analyze how many hours per week or per month you use or plan to use the internet. Many ISPs and IAPs offer flat monthly or annual rates, but some offer packages that charge for an initial hourly package and bill for any hours that exceed that amount. If you want your ISP to host your web site, you will need to assess how much disk storage, if any, your ISP offers with an account, as well as the price for additional MB of storage.

Shared resources Workgroup computing and groupware: workgroup computing also called collaborative computing, enables teams of co-workers to use networks of microcomputers to share information and to cooperate on projects. It is not only possible by networks and microcomputers but also by groupware. Groupware is software that allows two or more people on a network to work on the same information at the same time.

Shared resources Electronic data interchange: is the direct electronic exchange between organizations computer systems of standard business documents such as purchase orders, invoices, and shipping documents. Business to business transactions conducted via a computer network. In order to use EDI, organizations must have compatible computer systems, or else go though an intermediary.

Shared resources Intranets and Firewalls: Intranets are internal corporate networks that use the infrastructure ad standards of the internet and the world wide web. One of the greatest considerations of an intranet is security. Firewall as a security system is employed in intranets. A firewall is a system of hardware and software that connects the intranet to external networks, such as the internet. It blocks unauthorized traffic from entering the intranet and cal also prevent unauthorized employees from access the intranet

Shared resources Two components of firewalls are a proxy server and caching. Proxy server is a server, or remote computer, that may exist outside of the organization’s network, ad all communications to the organization are routed through it. The proxy server decides which messages or files are safe to pass through to the organization’s network. It can also provide document caching

Shared resources Caching is to store copies of web pages for quick access; the purpose is to speed up the web for their users. The only difficulty with this practice is that the original web page may have been updated, but this is not reflected on the copy in the cache in the proxy computer.

Shared resources Extranets: are extended intranets connecting not only internal personnel but also selected customers, suppliers, and other strategic offices