An ATM network is composed of one or more interconnected ATM switches, each having point-to-point attachments to ATM users. The following features are found in an ATM network:

• Interface types

  The interface between ATM switches is called a Network to Network Interface (NNI). The interface between an ATM switch and an end user is called a User to Network Interface (UNI), which is the interface between a public ATM carrier and a customer's switch.

• Switch types

  ATM switches come in a variety of types and sizes. A small switch (a few gigabits) is called customer premise equipment (CPE). A large switch (100 GB or larger) is called a central office (CO) switch. A CPE and CO cannot be defined in terms of speed. They also have different MTBF rates.

• Attached devices

  Attached devices can range from residential television sets to large computers.

• Link speeds

  ATM networks support a variety of link speeds, from 1.544 Mbps to 622 Mbps and higher.

• Attach media

  Users can attach by means of category 3 and category 5 for copper interfaces and multimode or single mode for fiber-optic interfaces.