#263Tech: What is an Internet Exchange Point (IXP)?

Recently, the Postal and Telecommunications Regulatory Authority of Zimbabwe (POTRAZ) announced plans to start the process of setting up Internet Exchange Points (IXPs) to improve information access around the country.

An Internet Exchange Point is a convergence zone where Internet networks come together to peer or exchange traffic between their networks.

You must remember that the Internet is a conglomerate of small networks like Wide Area Networks (WANs) encompassing Local Area Networks (LANs) all inter-joined together on an Internet Exchange Point (IXP) to form the Internet itself.

These are often misconstrued as internet service providers but they are not. While they allow network operators to exchange traffic with other network operators, an exchange point will not sell you anything resembling complete Internet connectivity. They are, instead, one of the building blocks around which the Internet is built.

Who Connects To Them?

Any network that wants to peer with other networks can connect to an exchange point. Traditionally, this meant Internet service providers (ISPs), who would sell Internet access to their customers. They would interconnect with each other at exchange points to allow their customers to communicate. More recently, exchange point customers are often content providers, who peer with ISPs to get their content to the ISPs’ customers. Content providers also connect to exchange points to exchange traffic with other content providers, including advertising networks interconnecting with advertiser-supported websites, email providers exchanging email messages, and the like.

What Is An Internet Exchange Point, Technically?

An exchange point is usually an Ethernet switch, much like the Ethernet switches that connect computers in an office network. Each network connecting to the exchange point connects one or more of its routers to the exchange point’s Ethernet switch, and they send traffic across the Ethernet switch to routers belonging to other networks.

Nigerian internet exchange point

Nigerian Internet exchange point

Where Are They?

Exchange points are usually in big telecom buildings where the networks that connect to them also have equipment. This makes it simple to run the connections, but means that a problem in a single building can damage a large number of networks. Netnod takes a different approach, keeping its exchange switches in underground telecom bunkers, and having networks connect to them via fiber cables from other buildings. However, in Stockholm, Netnod has expanded its exchange switch fabric with DWDM equipment at the major data centres. Netnod has also installed switch equipment at other sites in Stockholm, to make it easy for networks to connect to the Netnod exchange from different locations.

Who Operates Exchange Points?

Several different types of organizations operate exchange points. Some are operated by organizations made up of the members who connect to the exchange. Others are operated by commercial organizations, sometimes to facilitate interconnections in buildings they own, and sometimes as tenants of collocation facilities just like the networks that connect to them.