AAL2 is a protocol optimized for transporting short, variable-length packets with strict timing requirements over an Asynchronous Transfer Mode network. It minimizes latency by packing multiple small payloads, such as compressed voice frames from cellular base stations, into a single 53-byte ATM cell. This multiplexing capability makes it highly efficient for voice trunks and mobile backhaul connections.
The 3G Node B connects back to the radio network controller using AAL2 over the ATM transport layer.
Do not mix it up with
- AAL5: AAL2 is optimized for short, timing-sensitive voice payloads, whereas AAL5 is designed for larger, variable-length data packets without strict timing.
Related terms
AAL
A protocol layer that formats higher-level data into standard cells for asynchronous transfer mode networks.
AAL5
An ATM adaptation layer optimized for transporting standard data traffic like IP packets.
ATM
A telecommunications standard that switches traffic in fixed-size 53-byte cells.
Base station subsystem
The section of a cellular network that manages radio links between mobile devices and the core network.