ATM AAL Layers-Difference between AAL1,AAL2,AAL3,AAL4,AAL5
Refer Following links to subtopics on ATM tutorial:
ATM Network Architecture & Interfaces
ATM Protocol Stack
ATM services
ATM Switch
ATM Call Flow
ATM vs STM
ATM vs TDM
ATM versus Frame Relay
ATM AAL Layer Types
This page compares ATM protocol layers AAL Type 1 to 5 i.e. AAL1, AAL2, AAL3, AAL4, AAL5 and mention difference between AAL1, AAL2, AAL3, AAL4,
AAL5 ATM protocol layers. ATM Adaptation layers are classified based on their support for various service classes as well as following
parameters:
• Timing between source and destination (required or not required)
• Bit rate (constant or variable)
• connection mode (whether connection oriented or connectionless)
• AAL service Classes- A/B/C/D

Fig-1:ATM AAL Layers
AAL Layer in ATM is divided into two sublayers viz. Convergence Sublayer (CS) and
Segmentation and Reassembly Sublayer(SAR) based on functionality of AAL layer.
The function of ATM Adaptation layer in ATM protocol stack are summarized below:
CS sublayer performs following functions:
• management of lost and wrongly delivered ATM cells
• Timing recovery
• Interleaving

Fig-2:ATM Protocol Stack
SAR sublayer performs following functions:
• Fragmentation of bit stream from upper layers into size equal to ATM cells for transmission to ATM layer in the stack.
• Reassembly of ATM cells into bit stream for delivery to upper layers.
The figure-2 depicts ATM protocol stack mentioning AAL layer.
Refer ATM Protocol Stack➤.
ATM AAL1(AAL Type-1) Protocol Layer

Fig-3:ATM AAL Type-1 (AAL1)
The figure-3 depicts ATM AAL1 (Type-1) protocol layer fields.
ATM AAL2(AAL Type-2) Protocol Layer

Fig-4:ATM AAL Type-2 (AAL2)
The figure-4 depicts ATM AAL2 (Type-2) protocol layer fields.
ATM AAL3(AAL Type-3), AAL4(AAL Type-4) Protocol Layer

Fig-5:ATM AAL Type-3/4 (AAL3/AAL4)
The figure-5 depicts ATM AAL3/AAL4 (Type-3 and Type-4) protocol layer fields.
ATM AAL5(AAL Type-5) Protocol Layer

Fig-6:ATM AAL Type-5 (AAL5)
The figure-6 depicts ATM AAL5 (Type-5) protocol layer fields.
What is Difference between
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Difference between SC-FDMA and OFDM
Difference between SISO and MIMO
Difference between TDD and FDD
Difference between 802.11 standards viz.11-a,11-b,11-g and 11-n
OFDM vs OFDMA
CDMA vs GSM
Bluetooth vs zigbee
Fixed wimax vs mobile
wibro vs mobile wimax
Microcontroller vs microprocessor
FDM vs TDM
wimax vs lte