Our discussion of networking thus far has been fairly company-centric, meaning we have talked about LAN and WAN technology in terms of providing a network infrastructure for a single company or institution. Even our discussion of wide area networking was a look at providing data communication avenues between remote sites and the company's central LAN.
Another important aspect of networking the enterprise involves providing users with a conduit to the Internet. Although the rationale for connecting a company to the Internet can at times seem to be based on nothing more than a high-placed corporate officer shouting "Everyone else is doing it" at a board meeting, it falls on the network administrator or the administration team to determine the best way to connect the company's network infrastructure to the Internet backbone. This usually means researching local Internet service providers (ISPs) and different WAN technology options for the connection between the corporate network and the ISP (with the ISP providing the onramp to the Internet backbone). Before we talk about ISPs and some of the issues related to selecting a connection type (we discuss the various WAN technologies used to connect to the Internet in Chapter 13, "Expanding a LAN with WAN Technology"), let's take a look at how the Internet backbone is structured to provide communication among Internet service providers.
Accessing the Internet Backbone
When ARPAnet was first being developed, its creators wanted to create a packet-switching network that provided redundant paths for data transfer. ARPAnet was to serve as an internetwork (a network of networks) connecting government and educational institutions that could still move data even if sites or network paths became disconnected from the network backbone (that is, destroyed in a nuclear holocaust). As the ARPAnet evolved into the Internet, however, businesses and individuals wanted connections to the Internet backbone. This is where the Internet service provider (ISP) or Internet access provider (IAP) comes in.
Although the terms ISP and IAP are often used interchangeably when referring to companies that provide Internet access, for our discussion, I'd like to differentiate between the two. ISPs typically serve the little guy, such as a home user or small business, who wants to connect to the Internet and take advantage of Internet email, the WWW, and other Internet services. So, let's say that ISPs (because of the word service in the name ) provide Internet connections to users and companies and offer services such as Internet email, Web browsing, FTP, and newsgroupsall the typical Internet services. They may even provide some space on their Web servers for user Web pages and may also provide the DNS servers required for connection to the Internet.
An ISP doesn't have to be a monster organization that is directly connected to the Internet backbone. An ISP can actually lease its connection to the Internet from an IAP.
So, what's an IAP? An IAP would be a communications company that only provides a connection to the Internet. The companies served by an IAP (usually larger companies and even ISPs) would be responsible for their own DNS servers, mail servers, and so on. The IAP only provides the onramp to the Internet and actually connects to the Internet backbone via a network access point (NAP) . An NAP is a public exchange facility that provides connections for any number of IAPs to the Internet backbone.
So, now you are probably wondering how these different network access points are connected. The different NAPs are actually connected by a set of trunk lines (which are part of the Internet backbone). Sprint is an example of a company that operates a NAP.
Each of the NAPs rests on one of the Internet trunk lines, and these trunk lines allow the Internet access providers to communicate with each other (the end result of their communications is the movement of data over the Internet). An Internet trunk line (and there are currently seven in the United States) is referred to as a metropolitan area ethernet (MAE) . The first MAE line was created in Washington, D.C., and is referred to as MAE East . The MAE that primarily serves the Silicon Valley is referred to as MAE West (kind of figures, doesn't it?).
So, to make a long story short, unless you are a very large company, you probably won't be directly connected to the Internet backbone by an NAP. Your connection will be downstream of the backbone, provided by the linking of your ISP to larger IAPs or companies that have NAP connections.
Choosing an Internet Service Provider
It really goes without saying (although I'm going to say it anyhow) that you should carefully research the different ISPs available for connecting your company to the Internet. Depending on where your business is located, there might be as many ISPs to choose from as used-car dealers. You should also exercise the same caution in choosing an ISP that you would when buying a used car.
While selecting an ISP for a home network or small office isn't as crucial as selecting an ISP for a large corporate network (unsatisfied home networks and small companies can usually switch ISPs fairly quickly without that much disruption to the business), you should be sure that you select an ISP that provides good support in case you have problems configuring your network computers to connect to the Internet. You should also look for an ISP with a good track record and one that supplies you with extras such as additional email accounts at a reasonable fee.
Obviously, how your company or small business is planning to use the Internet will color how you choose your ISP. For example, if your Internet connection is extremely important to how your company does business, you will want to select an ISP that can ensure a consistent connection. The following list of questions provides some issues that you will want to explore when selecting your ISP, particularly in situations where you are connecting a larger company to the Internet:
Although this list doesn't take into consideration any special requirements or your actual Internet connection needs, you probably get the picture that your choice of ISP shouldn't be based totally on price (the same goes with used cars ). You need to take the time to be sure the ISP has the experience and connectivity muscle that will assure you of a consistent and cost-effective connection to the Internet. Don't be afraid to ask an ISP for references. Taking the opportunity to talk to other clients of the ISP might prove to be the most valuable research you do when selecting an ISP.
Choosing a Connection Type
Your connection to your ISP can take advantage of any of the different WAN connectivity strategies we discussed in Chapter 13. The connection type you choose should provide enough bandwidth to handle the movement of data between your network users and your ISP. For example, a small business might be able to get away with a 640Kbps DSL connection. A larger business might require a fractional T-1 or a full T-1 carrier line to provide the appropriate data transfer pipe.
During your initial dialogue with a prospective ISP, you need to find out how much experience it has with the different WAN possibilities for connecting your company to it. An ISP with a proven track record of providing connections for businesses can also provide you with information on the type of connections it provides to other clients.
One connection type that we didn't take a look at when we discussed the various WAN technologies in Chapter 13 is the cable modem. It provides an alternative for small companies looking for a connection to the Internet in markets where DSL isn't available or in situations where ISDN just doesn't provide enough bandwidth. Cable companies such as Time Warner (which is known as Bright House in some markets) offer cable modem connections.
Cable modem connections take advantage of the cable TV infrastructure. Data is moved on different frequencies (or channels , if you prefer). Upstream and downstream data typically require separate frequencies. Although cable modem technology and the methods for allocating bandwidth are still being developed, bandwidths in excess of 2Mbps (with the possibility of speeds up to 30Mbps) can be experienced using the technology (the more bandwidth you want, the more you pay the provider). Because a cable company that offers broadband cable modem connections also serves as the ISP for these connections, a small company that wants a connection to the Internet, but does not necessarily consider the connection to be mission critical, might want to consider broadband as a possible connection.
A number of cable television providers, such as Time Warner, now offer cable modem connections for home networks, small businesses, and even larger businesses. Different connection packages are available that supply varying amounts of bandwidth. The cable modem itself supplies the connection between the ISP (the cable company) and its Internet gateway server. The cable modem is connected to a regular television coaxial cable outlet. You can then connect the cable modem to your router, switch, or hub using CAT 5 twisted-pair cabling.
In many regional cable markets, even the basic home cable modem package will provide dynamically assigned IP addresses and enough bandwidth for five networked computers. It is a very good way to share an Internet connection in a home or small office situation.
Regardless of the technology you choose for your connection to your ISP, you need to be sure you understand that particular WAN technology and how to secure IP traffic between your network and the ISP. The use of firewalls and other security strategies such as IPSec (firewalls and IPSec are discussed in Chapter 20) should also play a part in your overall planning of the connection of your network to the Internet.