Summary

The ATM Adaptation Layer (AAL) type 3/4 enhances the service provided by the ATM layer to support functions required by the next higher layer. This AAL performs functions required by the user, control and management planes and supports the mapping between the ATM layer and the next higher layer.

The AAL type 3/4 supports the non-assured transfer of user data frames. An internal mulitplexing function allows the establishment of several concurrent AAL type 3/4 user connections on one ATM connection. On each such connection, the data sequence integrity is maintained and transmission errors are detected.

Two new appendices describe the multiplexing AAL type 3/4 connections on an ATM connection using the Multiplexing Identification (MID) field and one procedure for dynamic MID allocation.