|
ATM adaptation layer
Service-dependent sublayer of the data link layer. The AAL accepts data from
different applications and presents it to the ATM layer in the form of 48-byte
ATM payload segments. AALs consist of two sublayers, CS and SAR. AALs differ on
the basis of the source-destination timing used, whether they use CBR or VBR,
and whether they are used for connection-oriented or connectionless mode data
transfer. At present, the four types of AAL recommended by the ITU-T are AAL1,
AAL2, AAL3/4, and AAL5. See AAL1, AAL2, AAL3/4,
AAL5, CS, and SAR. See also ATM and ATM
layer.
|