Like the frame relay and X.25, ATM is also connected to the connection. ATM procedures are divided into three layers: The following is a physical layer.
The middle is an ATM layer, which is an ATM adaptation layer. The physical layer specifies the interface between ATM data streams and physical media.
Includes two sub-layers: physical media related sub-layers and transmission gratum layers. Physical media related sub-layers specified ATM
The rate of transmission through a given medium is streamed. The conventional sub-layer specifies the cells transmitted by physical media related sub-layers.
Procedure. The ATM layer is the core of ATM technology, although there are multiple ATM adaptation layers and multiple physical layers to choose from, but
The structure of the letter and the control cell exchange is fixed, and the difference is not different due to the distinction. ATM layer is responsible
Elementary circuit, multiplexing, and repeated use.
The highest layer of the ATM procedure is the ATM adaptation layer (AAL). It converts the high-level user service into the format and length in the ATM, and then converts it to the original user service after the destination station. This layer includes five sub-layers (AAL1-AAL5), and different ATM adapted sub-layers are consistent with different services supported by ATM. AAL1 supports fixed bit rate (CBR) services, such as digitized sounds and image signals for applications that are sensitive to cell delays and loss; AAL2 supports time-sensitive variable bit rate (VBR) services; AAL3 / 4 Supports connection-oriented burst business, and data services; AAL5 supports burst LAN data services. The AAL layer can also integrate the connected ATM with unconnected data, allowing ATM users to broadcast and a point-to-multipoint communication.
