I’m sitting in Room 50 on the fourth floor of 721 Broadway, connected to the NYU wifi. I enter www.anotheridea.co in my browser and think “Oh no, I’m late on another blog post.” But then I wonder, “How did my website content get to being on my screen? Where does it live? Does it even live somewhere? Maybe I should write that blog post…”
Connecting to a Network, ISPs and IXps
In connecting to a network, there are consumers and content providers. Consumers request data—email, the news, Netflix, etc— and content providers serve up the requested data.
I, as a consumer, connect to the Internet from various networks — perhaps on my local network at home, at the neighborhood coffee shop or the ITP floor. My network connection to the Internet is facilitated by an Internet Service Provider (ISP) which owns cables and sells access to a network. And similarly, content providers also access the Internet through an ISP. Some of the largest ISPs are Comcast, AT&T, Time Warner and Verizon.
Consumers, content providers, and all the data in-between, access the Internet from many different networks. As such, these different networks need to connect to each other for data to be transmitted efficiently — that connection happens at particular points in space using particular protocols.
Major networks connect through Internet Exchange Points
At Internet Exchange Points (IXPs), three or more autonomous network systems connect and directly exchange traffic, rather than routing through third-party networks. IXPs are company-owned physical network access points, providing access to a patch panel which connects to other networks. They might own their buildings, or just patch panels in other buildings—such as in a third-party colocation facility.
IXP participants are commonly Internet Service Providers but may also include common carriers, content distributors (i.e. Netflix), hosting providers (i.e. Bluehost), or research and/or education networks (i.e. New York University), among other classifications. Common carriers transport goods–such as data or internet access–for hire as a business to any customer willing to pay and must provide the same level of service to all potential customers indiscriminately. ISPs are considered common carriers.
Colocation and Interconnection Facilities
Broadly, any space in which different networks connect can be called an “interconnection facility”. An interconnection facility is a particular physical location–be it an entire building or part of one–that offers secure space for networks to locate and operate equipment–routers, end devices, access switch–for making connections between other networks. Co-locating network equipment makes data transfer across networks more efficient. Colocation might describe locating one’s server near an ISP’s endpoint, or it might describe locating one’s routers near an ISP or IXP location to maximize the connections to other networks.
Such facilities can be distinguished across a number of aspects:
- Locations may be carrier-neutral, such as Neutrality Properties which operates as a “landlord” and does not operate networks itself. Alternatively, they may operated by carriers or Internet Service Providers, such as Level 3 (now owned by CenturyLink) which operates a Tier 1 network. (Tier 1 networks can reach every other network through free peering with every other Tier 1 network.)
- Locations can be multi-tenant or have an exclusive tenant which simply connects to its own networks.
- Locations can offer various series and environments potentially including backup power generators, cooling system, dedicated cabling, particular administration agreements, etc.; and
- Some locations provide access to the ends of fiber optic cables
How do networks “talk” to each other?
A network, or collection of networks, managed by a single organization is known as an autonomous system (AS) and is identifying by an autonomous system number provided by ICANN. Within an autonomous system, networks communicate using an Interior Gateway Protocol, while Border Gateway Protocol is used between autonomous systems. Border Gateway Protocol links a system with its number(s) and routes (Sugeno, 92). A connection between two AS networks is made by each announcing its routes via BGP and also updating its routing table to acknowledge the routes of another network. For further discussion of routing protocols, see Mithru’s article. As of Monday, October 30th, 2017, there are almost 60,000 unique autonomous networks. (See the CIDR report: http://www.cidr-report.org/as2.0/)
A History of Interconnection Facilities
A rise in colocation facilities were driven by deregulation of local telecommunication services set forth in the Telecommunications Act of 1996. Regional carriers and local exchange carriers were required to connect to other carriers, to install network features, and to provide physical colocation. (Evans-Cowley, 552). Additionally, development of colocation facilities was fuelled by rapidly expanding Internet usage, the spread of consumer computer networking, and customer demand for faster transmission speeds. In the late 1990s, more and more internet consumers were transferring large amounts of data: files, email, video, audio, and so forth. Similarly, numerous IXPs were also established throughout the 1990s and coincided with the development of these facilities.
Conclusion
The necessity of a physical connection–whether at a patch panel or access switch–between different networks underscores the often-forgotten tangibility of networks. Although the exchange of bits and bytes can seem abstract–their transfer is only possible through vast physical infrastructure, evident in the windowless buildings filled with conduit, lights, and tubes.
Sources (links throughout, journal references here):
Giotsas, Vasileios, et al. “Mapping Peering Interconnections to a Facility.” Proceedings of the 11th ACM Conference on Emerging Networking Experiments and Technologies – CoNEXT ’15, 2015.
Evans-Cowley, Jennifer. “A New Land Use in Downtown: How Cities Are Dealing with Telecom Hotels.” Journal of Urban Affairs, vol. 25, no. 5, 2003, pp. 551–570.
Sugeno, Akio. “Improve Availability of Networks: Internet Exchange Points and Their Role in Cyberspace.” Advances in Cyber Security, Mar. 2013, pp. 90–106.