A day in the life of the Internet: London

On Jan. 19, we stationed reporters at eight network access points around the globe to find out just what it takes to keep the Internet humming.

By Jana Sanchez
Network World, 03/01/99

LONDON, JANUARY 19 -- Getting past the three layers of security at Telehouse, where London's Internet Exchange (LINX) is housed, is a challenge akin to breaking into James Bond's MI6 HQ.

A history here of terrorism, flooding and the fear of power outages and

natural emergencies led to the creation of a state-of-the-art secured building. The several layers of re-enforced glass security doors that require pass cards and pass codes to enter testify to the significance of what is housed within.

For here, along with a presence by all major U.K., European and U.S. telcos, are found the switches and routers through which more than 90 percent of all domestic U.K. Internet traffic passes.

The morning of our visit, the only human around was engineer Jerry Reilly, whose makeshift, fold-out desk, holding a tiny laptop computer, protrudes from one of the racks. Normally, he would be at LINX's office in Peterborough in Cambridgeshire, since almost any problem that could arise can be solved remotely.

LINX, a not-for-profit group, is composed of the U.K.'s Internet service providers (ISPs) and allows all Internet traffic that originates in the U.K. destined for other U.K.-based servers to stay in the U.K. While not all U.K. ISPs are themselves members, all of them, except for America Online Inc., exchange their domestic traffic using LINX through one of the member ISPs. This means that when a request for a Web page or e-mail coming from a user on a U.K. ISP, such as Demon Internet, is destined for another U.K.-based ISP, such as BT.net, then instead of that traffic going onto the international backbone, it goes directly through the switches at LINX from one ISP to the other.

In addition to keeping traffic between U.K. Internet users on the island, LINX, one of the largest and fastest growing exchange points in Europe, works to improve connectivity between the U.K. and the rest of the world, said Reilly. If U.K. internal traffic stays in the country, it reduces traffic congestion on the European and trans-Atlantic backbones.

Currently members pay a one-time joining fee of 10,000 and 12,000 pounds per year. Some ISPs that use extra resources, such as extra ports or extra traffic, pay additional charges.

The actual LINX suite in Telehouse is only about 15 square meters and every bit of it, except for aisle space, is stuffed with racks holding switches and other equipment. No one works on site. Rather three engineers, who split a 24-hour shift, are notified via their mobile phones if a problem arises and they rush over or, more likely, solve the problem remotely.

The core of the exchange is a Packet Engines Inc. 5200 Gigabit routing switch. This mammoth switch can more than handle the traffic that comes through the LINX, said Keith Mitchell, executive chairman of LINX. To date, the switch has cost LINX about 100,000 pounds sterling. Providing backup for that switch, in the event of technical faults, are two Plaintree Systems Inc. WaveSwitch 4800 switches and two Cisco Systems Inc. 5000 switches. The system accommodates 70 ports.

ISPs who have space in Telehouse, within 130 meters of the LINX suite are connected via copper to the LINX switches. Those that are more than 130 meters away are connected via FDDI. Space is tight in Telehouse right now and even some ISPs who want space there cannot get it. But relief is on the way with the Telehouse 2000 extension, being build adjacent to the building.

Traffic peaks normally about 2 p.m. at around 400M bits per second. The traffic is about the same every week day, with weekends being lighter. With the switch LINX has, it can easily accommodate even the busiest times.

In fact, LINX has never gone down. There were two minor incidents caused by a Telehouse employee switching off the power supply in error, but noone completely lost service, said Mitchell.

Read the stories of individual NAPs by clicking on their city name below: