WANs I: LANs, MAN’s and WAN’s Oh My!

A Wide Area Network

I started my career in the networking industry at a small Internet Service Provider in Seattle, Washington in the United States (this was in the late 1990’s).  At that time, most end-users accessed the Internet using dial-up connectivity, and modem speeds topped out at about 28 Kbps (yes, it sounds like ancient history).  From there I went to work for AT&T, where I spent the next five or so years assisting Fortune 500 businesses connecting multiple locations together; needless to say, I spent a lot less time dealing with Wide Area Networks than Local Area Networks.

Although I have since mastered LAN’s, I still have a great fondness for WANs and enjoy building labs that simulate them. LANs are suspiciously easy to recognize, first because they use Ethernet switches, but also because they occupy a fairly localized geographical area (hence the term LAN).  Wide area networks are also easy to recognize, as they almost universally depend on large telecommunications providers (AT&T, Verizon, British Telecom, etc.) and use an entirely different set of connections to provide services with.  A term that can be confusing, however, is that of a MAN or Metropolitan Area Network, and as such, needs some clarification.

The simplest way to differentiate MANs from WANs is to look at geography once again.  LANs connect computing devices with a floor, building, or campus, but no further than that.  WANs include networks that tie together sites across significant distances, such as nationally or internationally.  MANs are networks that lie within a smaller, more specific region; in a sense all MANs are WANs but not all WANs are MANS.  Think of the concepts like squares and rectangles; all squares are rectangles but not all rectangles are squares (using the classic shape definitions).

The more technical way of explaining Metropolitan Area Networks involves a little bit of US telecommunications history, specifically when AT&T was broken up in the 1980’s.  In the new system following this “divestiture”, new regions were created within states called local Access Transport Areas, or LATAs.  Local phone companies (e.g., Bell Atlantic, Pacific Bell, etc.operated in these LATAs, and Inter-Exchange Carriers (IXC’s) created connectivity between these areas; each had to operate separately.  In this arrangement, a MAN would be between locations within a LATA, while a WAN would be between them.  Usually this would encompass a city and its outlying suburbs and such, hence the term “metropolitan.”  With regulatory changes, these distinctions are not nearly as relevant, which explains why the term MAN is far less frequently used.

Next time we will look at some of the types of WANs that exist today!

– Joe


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