> For the complete documentation index, see [llms.txt](https://azunyan.gitbook.io/internet-protocol/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://azunyan.gitbook.io/internet-protocol/1.-computer-network-and-the-internet/1.2-the-network-edge.md).

# 1.2 The Network edge

#### 1.2.1 Access Networks

Access network—the network that physically connects an end system to the first router (also known as the “edge router”) on a path from the end system to any other distant end system.

Today, the two most prevalent types of broadband residential access are **digital subscriber line (DSL)** and cable.

A residence typically obtains DSL Internet access from the same local telephone company (telco) that provides its wired local phone access. Thus, when DSL is used, a customer’s telco is also its ISP.

The residential telephone line carries both data and traditional telephone signals simultaneously, which are encoded at different frequencies.

While DSL makes use of the telco’s existing local telephone infrastructure, cable Internet access makes use of the cable television company’s existing cable television infrastructure. A residence obtains cable Internet access from the same company that provides its cable television.

#### 1.2.2 Physical media

Physical media fall into two categories: guided media and unguided media. With guided media, the waves are guided along a solid medium, such as a fiber-optic cable, a twisted-pair copper wire, or a coaxial cable. With unguided media, the waves propagate in the atmosphere and in outer space, such as in a wireless LAN or a digital satellite channel.


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