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A metropolitan area network (MAN) is similar to a local area network (LAN) but spans an entire city or campus, or some other municipal or organizational territory. MANs are formed by connecting multiple LANs. Thus, MANs are larger than LANs, but smaller than wide area networks (WAN) that cover dispersed geographical areas, sometimes directly connecting users around the world.
MANs are typically extremely efficient and can provide fast communication via high-speed carriers, such as fiber optic cables. The rise of wireless and successive networking technologies, though, means a proliferation of modalities for getting signals around a greater MAN area.
A MAN is ideal for many kinds of network users because it is a medium-size network. MANs are used to build networks with high data connection speeds for cities and towns.
The working mechanism of a MAN is similar to an Internet Service Provider (ISP), but a MAN is not owned by a single organization. Like a WAN, a MAN provides shared network connections to its users. A MAN mostly works on the data link layer, which is Layer 2 of the Open Systems Interconnection (OSI) model.
Distributed Queue Dual Bus (DQDB) is the MAN standard specified by the Institute Of Electrical And Electronics Engineers (IEEE) as IEEE 802.6. Using this standard, a MAN extends up to 30-40 km, or 20-25 miles. MAN has benefited from technologies like dense wavelength division multiplexing and optical packet switching to emerge as a modern networking option for both municipalities and organizations such as universities.
Metropolitan area networks, according to their design, may deliver some benefits, such as firewall centralization. Having a more central gatekeeping point for the Internet can cut down on malware and other threats. A MAN may also provide more efficient forms of administration and data entry.
Cities implementing modern MANs may also have complementary technology implementations, such as Internet Exchange points.
However, MANs also carry some particular disadvantages. One of these is buy-in – the idea that there must be some coherent push to adopt a metropolitan area network, and accommodate its use, which is where some of these implementations run into problems.
One barrier to implementing MANs is that ISPs often have objections to metropolitan area networks.
The reason is because an effective metropolitan area network makes it more difficult for ISPs to collect the fees that they get from managing local area networks in that covered region or area. It’s not hard to find evidence of this, if you look.
For example, a series of reports from Ars Technica from 2010 to 2014 provide ample evidence of ISPs working against MAN implementation, some citing such efforts in 20 U.S. states.
In general, we have seen the pushback against MANs hobble efforts to put these systems in place in many U.S. communities. The frontier of networking clashes with a profit motive. This is one central factor in the future of this type of municipal or civic networking option.