Asynchronous Transfer Mode

Asynchronous Transfer Model (ATM) operates at the OSI model layer 2 (data link) over either twisted pair or optical fiber.

The transmission unit in ATM is called cell. Cells are fixed-size.

ATM ensures that the cells are received in order, but it does not ensure that they are received.

ATM was conceived as an alternative to TCP/IP model’s ethernet, but it did not achieve success.

ATM was used mainly internally for the telecommunications companies.

ATM Services

ATM Services featured on this post:

Unspecified Bit Rate (UBR) does not have a reserved fixed flow.

Available Bit Rate (ABR) does not have a reserved fixed flow.

Constant Bit Rate (CBR) is a connection-oriented service.