Tuesday, October 13, 2009

Question and Answers

Questions and Answers concerning particular and often very detailed issues given without introduction.
Comments, questions are of course welcome!!!

Q: Why AAL2 on Iu interface needs ALCAP and AAL5 does not need this signaling protocol ?
A: AAL5 is using PVC configured by O&M, hence there is no need to establish, release or maintain this connections. AAL2 is not using PVC but VC/VP which need to be established, released and maintained by separate signaling protocol i.e. ALCAP.

Q: What is the meaning of PDU and SDU and what is the difference between them ?
A: PDU is Protocol Data Unit and SDU is Service Data Unit. Difference between them and their role should describe following figure
PDU and SDU illustration

Q: What means NNI and UNI ? This two terms can be seen together with SAAL layer.
A: NNI means Network-to-Network Interface also known as Network-Node Interface. UNI means User-to-Network Interface.