In part one of this series we looked back at how computers first became linked and networked, and at some of the early pioneers that made today's Internet possible. Today we look at the companies that provide public support, the physical hardware, and the simple know-how that keeps the Internet traffic flowing.

In simple headline terms there are two distinct groups of commercial people operating in the Internet world. The so-called Internet Service Providers (the ISPs) and the so-called "backbone" companies - the people that provide the physical networks and connections along which the Internet traffic flows.This can involve copper wire networks, fibre optic streams and satellite links - in many cases a single Internet connection will involve all three mediums.

(To complicate the plot slightly, companies such as MCI also own - among various other assets - the ISP CompuServe. However let us ignore this slight complication today.)

This Internet apartheid is a natural one: ISPs deal with the general public, providing the software and customer care and dealing with low level problems; while the backbone companies get on with the single - but far from easy - task of getting the data from Point A to Point B in the quickest possible time.

Naturally ISPs are customers of these backbone companies (nearly all of which are also standard voice telephone companies) and pay for the privilege of using their transportation networks.

People often ask the question "where is the Internet physically?" The best answer is "everywhere and nowhere!" The data networks that carry the bulk of the data traffic are owned by the major telephone companies and are run alongside the standard voice traffic.

However setting up fibre optic and satellite networks, and deciding the correct levels of investment are always major headaches. The decisions of these backbone companies make will decide the speed that the Internet will operate at in the future - especially as more customers join the system.

Today four major telecommunications companies control more than 75% of all the Internet traffic: MCI Communications, Sprint, Worldcom and GTE.

MCI Communications first launched a commercial backbone service in 1994 after helping build and regulate the NSFNET (National Science Foundation InterNET). One of the forerunners to the Internet. It was MCI's Chief Engineer, Vinton Cerf, that co-invented the packet-switching protocol that is the basis of Internet communication today.

Earlier this year MCI agreed to be bought by WorldCom, but seems to have retained its separate identity. According to data provided by Boardwatch magazine MCI controls 31% of the Internet backbone market.

Sprint is one of the oldest phone companies in the world having been founded in 1899. It started its Internet service in 1992 and has complained (without notable success), to the US and European authorities about the merger outlined above. According to data provided by Boardwatch magazine Sprint presently controls 22% of the Internet backbone market.

WorldCom first entered the Internet market in 1996 when it bought the company UUNET Technology along with its parent phone company MFS Communications. In 1997 it took over ANSCommunications and CompuServe and customers include America Oneline and the Microsoft Network. According to data provided by Boardwatch magazine Worldcom presently controls 20% of the Internet backbone market.

GTE entered the backbone business in 1997 when it bought BBN, a company that helped build the first government run internet - APRANET - in 1969. The history of APRANET was explored in part one of this series. According to data provided by Boardwatch magazine GTE presently controls 4% of the Internet backbone market.

How these companies co-operate with the individual ISPs can perhaps be best explained by giving an example of how an E-mail gets from one place in the world to another.

Let us suppose User A in Glasgow wants to send an E-mail to User B in New York. User A is a subscriber to a small company called "Tartan Internet" and User B to a local ISP called "Stars and Stripes" Internet. The User A writes their message, primes their specialist E-mail software and presses the "send"button.

At this point Tartan Internet starts the ball rolling. They have a contract with a company called Frontier (not a real company) that connects their company with the rest of the Internet. The E-mail is passed on to them.

Frontier now has a problem, it is not linked to Stars and Stripes Internet so will need the services of a backbone carrier that is. They have two ways to do this, either as a "peer" or as a "customer." If two Internet carriers decide that they are of equal size they can exchange traffic with each other for free. They can do this directly or by linking at so-called "public peering points."

Stars and Stripes uses MCI as its gateway to the Internet which means that Frontier, in this instance, will have to pay a"transit" fee to send the mail to them who will, in turn, pass on the E-mail to Stars and Stripes Internet ready to be downloaded by User B.

This is the most complicated scenario: The most simple connection would be when both parties used the same ISP and the message could be exchanged without even going on to the Internet.

At one point in its history the Internet had only three major peering points: In Chicago, Palo Alto and Pennsauken - which is in New York State. However these connections became over burdened and were supplemented by so-called "private peering" These are direct, bilateral connections between two carriers in which no fees are charged.

Who will peer with who and under what circumstances is the bug-bear of the industry. WorldCom, for instance, will not peer with any carrier that doesn't have a national network capable of 45 million bits of data per second.

As time goes on the rules of peering have got tougher. John Sidgmore vice-chairman of WorldCom was recently quoted as say that "physically we cannot possibly peer with 7,000 ISPs."

In part three of this series we will look at the Internet regulators, domain name registers and some of the future based systems such as "off-line Internet."

(C) Peter Hayes