ISPs and the Types of Connections to the Internet

The ISPs short term for Internet Service Providers is the gateway to your wonder World of Internet. They give different types of access to Internet. The types of connection are broadly defined as per the equipment and its type of connection used to connect you to the Internet.

The Analog connection called as a Dial- up access was the earliest ways by which connections were established to the Internet using the Telephone Lines. It is both economical and slow. You use a Modem connected to your PC, and dial a phone number to connect to the Network. Typical Dial-up connection speeds range from 2400 bps to 56 Kbps.

The next better option came in the way of ISDN connections or Integrated Services Digital Network (ISDN) for sending Voice, Video, and Data over digital Telephone lines or normal Telephone wires. Speeds range from 64 Kbps to 128 Kbps. The B-ISDN, the Broadband ISDN is similar to ISDN but it transfers data over Fiber Optic Telephone lines.

The DSL has become the standard way to connect to the Internet and it provides an always on connection because it uses existing 2-wire copper telephone line and is always on. The two main categories of DSL for home subscribers are called ADSL and SDSL.
The ADSL short for Asymmetric Digital Subscriber Line supports Data rates of from 1.5 to 9 Mbps when receiving data (known as the downstream rate) and from 16 to 640 Kbps when sending data (known as the upstream rate). ADSL requires a special ADSL modem.

The SDSL, short for symmetric digital subscriber line, a Technology that allows more data to be sent over existing Copper Telephone Lines and supports data rates up to 3 Mbps. SDSL works by sending digital pulses in the high-frequency area of Telephone wires and can not operate simultaneously with voice connections over the same wires.

The VDSL or Very High DSL (VDSL) is a DSL technology that offers fast data rates over relatively short distances — the shorter the distance, the faster the connection rate.

Internet is provided in modern times through Cable TV lines by use of a Cable Modem and you get a broadband Internet and the Cable speeds range from 512 Kbps to 20 Mbps.
Wireless Internet Connection is one of the newest Internet connection types by using Radio frequency bands providing an always-on connection which can be accessed from anywhere.

In addition to these types of basic connections we have more types of leased lines like T1, T2, and T3 connections which are fully dedicated Lines giving exclusive access to Internet at much faster Data transfer speeds.

What Is an ISP and How to Choose One

An ISP, or internet service provider, is a company that provides its customers access to the internet and other web services. In addition to maintaining a direct line to the internet, the company usually maintains web servers. By providing necessary software, a password-protected user account, and a way to connect to the internet (e.g., modem), ISPs offer their customers the ability to browse the web and exchange email with other people. Some ISPs also offer additional services. With the development of smart phones, many cell phone providers are also ISPs.

ISPs can vary in size-some are operated by one individual, while others are large corporations. They may also vary in scope-some only support users in a specific city, while others have regional or national capabilities.

What services do ISPs provide?

Almost all ISPs offer email and web browsing capabilities. They also offer varying degrees of user support, usually in the form of an email address or customer support hotline. Most ISPs also offer web hosting capabilities, allowing users to create and maintain personal web pages; and some may even offer the service of developing the pages for you. Some ISPs bundle internet service with other services, such as television and telephone service.

Many ISPs offer a wireless modem as part of their service so that customers can use devices equipped with Wi-Fi. As part of normal operation, most ISPs perform backups of email and web files. If the ability to recover email and web files is important to you, check with your ISP to see if they back up the data; it might not be advertised as a service. Additionally, most ISPs implement firewalls to block some portion of incoming traffic, although you should consider this a supplement to your own security precautions, not a replacement.

How do you choose an ISP?

Traditional, broadband ISPs typically offer internet access through cable, DSL, or fiber optic options. The availability of these options may depend where you live. In addition to the type of access, there are other factors that you may want to consider:

security – Do you feel that the ISP is concerned about security? Does it use encryption and SSL to protect any information you submit (e.g., user name, password)? If the ISP provides a wireless modem, what wireless security standards does it support, and are those standards compatible with your existing devices?

privacy – Does the ISP have a published privacy policy? Are you comfortable with who has access to your information and how it is being handled and used?

Services – Does your ISP offer the services you want? Do they meet your requirements? Is there adequate support for the services? If the ISP provides a wireless modem, are its wireless standards compatible with your existing devices?

cost – Are the ISP’s costs affordable? Are they reasonable for the number of services you receive, as well as the level of those services? Are you sacrificing quality and security to get the lowest price?

dependability – Are the services your ISP provides reliable, or are they frequently unavailable due to maintenance, security problems, a high volume of users, or other reasons? If the ISP knows that services will be unavailable for a particular reason, does it adequately communicate that information?

user support – Are there published methods for contacting customer support? Do you receive prompt and friendly service? Do their hours of availability accommodate your needs? Do the consultants have the appropriate level of knowledge?

speed – How fast is your ISP’s connection? Is it sufficient for accessing your email or navigating the internet?

ISP’s and Internet Backbones

We saw earlier that end systems (user PCs, PDA’s, Web servers, mail servers, and so on) connect into the Internet via an access network. Recall that the access network may be a wired or wireless local area network (for example, in a company, school, or library), a residential cable modem or DSL network, or a residential ISP (for example. AOL or MSN) that is reached via dial-up modem. But connecting end users and content providers into access networks -is only a small piece of solving the puzzle of connecting the hundreds of millions of end-systems and hundred of thousands of networks that make up the Internet.

The Internet is a network of networks– understanding this phrase is the key to solving this puzzle. In the public Internet, access networks situated at the edge of the Internet are connected to the rest of the Internet through a tiered hierarchy of ISPs. Access ISPs (for example, residential cable and DSL networks, dial-up access networks such as AOL, wireless access networks, and company and university ISPs using LANs) are at the bottom of this hierarchy. At the very top of the hierarchy is a relatively small number of so-called tier-1 ISPs. In many ways, a tier-1 ISP is the same as any network–it has links and routers and is connected to other networks. In other ways, however, tier-I ISPs are special. Their link speeds are often 622 Mbps or higher, with the larger tier-I ISPs having links in the 2.5 to 10Gbps range; their routers must consequently be able to forward packets at extremely high rates. Tier-I ISPs are also characterized by being:

* Directly connected to each of the other tier-1 ISPs

* Connected to a large number of tier-2 lSPs and other customer networks

* International in coverage Tier-l ISPs are also known as Internet backbone networks.

These include Sprint, Verizon, (previously UUNet/WorldCom), AT&T, NT]’, Level3, Qwest, and Cable & Wireless. Interestingly, no group officially sanctions tier-I status; as the saying goes–if you have to ask if you are a member of a group, you’re-probably not. A tier-2 ISP typically has regional or national coverage, and (importantly) connects to only a few of the tier-I ISPs thus, in order to reach a large portion of the global Internet, a tier-2 ISP needs to route traffic through one of the tier-I ISPs to which it is connected. A tier-2 ISP is said to be a customer of the tier-I ISP to which it is connected, and the tier-1 ISP is said to be a provider to its customer. Many large companies and institutions connect their enterprise’s network directly into a tier-I or tier-2 ISP, thus becoming a customer of that ISP. A provider ISP charges its customer ISP a fee, which typically depends on the transmission rate of the link connecting the two. A tier-2 network may also choose to connect directly to other tier-2 networks, in which case traffic can flow between the two tier-2 networks without having to pass through a tier-I network. Below the tier-2 ISPs are the lower-tier ISPs, which connect to the larger Internet via one or more tier-2 ISPs. At the bottom of the hierarchy are the access151’s. Further complicating matters, some tier-I providers are also tier-2 providers (that is, vertically integrated), selling Internet access directly to end users and content providers, as well as to lower-tier ISPs. When two ISPs are directly connected to each other, they are said to peer with each other. An interesting study [Subramanian 2002] seeks to define the Internet’s tiered structure more precisely by studying the Internet’s topology in terms of customer- provider and peer-peer relationships.