ATM A Connection Oriented Cell Switching Technology The objective of this lab is to examine the effect of ATM adaptation layers and service classes on the performance of the network. Overview Asynchronous Transfer Mode (ATM) is a connection-oriented, packet-switched technology. The packets that are switched in an ATM network are of a fixed length, 53 bytes, and are called cells . The cell size has a particular effect on carrying voice traffic effectively. The ATM Adaptation Layer (AAL) sits between ATM and the variable-length packet protocols that might use ATM, such as IP. The AAL header contains the information needed by the destination to reassemble the individual cells back into the original message. Because ATM was designed to support all sorts of services, including voice, video, and data, it was felt that different services would have different AAL needs. AAL1 and AAL2 were designed to support applications, like voice, that require guaranteed bit rates. AAL3/4 and AAL5 prov
