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Now, as mentioned, VPNs or virtual private networks have replaced a lot of deployments of leased lines,

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but you'll still find them.

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They've been around for a very long time, and depending where you are in the world, this may be the

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only way to get a high speed connection to a business site.

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Now, because these have been around a long time and have been used in various parts of the world they

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often referred to with different terms or different names.

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So the first term is a leased line, which once again implies that you are leasing the line from a provider.

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You don't own the connection.

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You are paying a monthly fee, in other words, a monthly leasing fee to lease the line from the service

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provider, which would typically be a telephone company or telco such as AT&T or British Telecom.

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So some terms that you may come across include leased circuit or leased line.

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These terms are often used interchangeably.

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A circuit refers to the actual electrical circuit between the two endpoints.

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In the old days, we used to have circuit switched networks.

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Where you'd make a telephone call between two sites and use an analog modem to send traffic between

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those two sites.

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So it was a circuit that was established for the duration of your telephone call.

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A leashed line, however, is a dedicated circuit between two sites, so you don't have to make a call

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to send data across it.

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It's a permanent point to point connection between the two sites.

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You may also come across the term serial link or serial line.

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Once again, these are used interchangeably and mean the same thing.

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The term serial in this case refers to the fact that the bits sent across the wire flow serially and

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that routers use serial interfaces to make the connection a point to point link or point a point at

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least line refers to the fact that you are making the connection between two points rather than between

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multiple sites at the same time.