Asymmetric.pptVIP

COMP514 – ADSL DSL connection DSL Lecture Topics ADSL – customer access DSLAM MDF LLU ADSL Asymmetric Digital Subscriber Line Core idea: utilises existing copper used for the phone network Voice signals in 4kHz; most copper is capable of transmitting more than this across a short distance Divide the copper into frequencies used for voice and frequencies used for data via splitter ADSL filters ADSL ADSL splitter portions off frequencies lying between 25.875 khz and 1104 kHz Upstream 25.875 kHz to 138 kHz Downstream 138 kHz to 1104 kHz Asymmetric Divided into channels of 4.3125 kHz ADSL modems test channels for interference, use channels that are acceptable More channels == more bandwidth DSLAM Digital Subscriber Line Access Multiplexer Houses a large number of DSL modems MDF Main Distribution Frame Copper Aggregation point Terminates local-loop Central Office Large building that holds telephone switch equipment, DSLAM, etc. e.g. Big White Building on Galloway St. Mini-DSLAM Installed in a roadside cabinet Low power devices, strict heat requirements A unit that is situated closer to customers who are too far away to get DSL service via telco’s central office Backhaul to central office. Local Loop Unbundling (LLU) LLU allows an ISP to place their own equipment in an exchange and provide their own data services over the local-loop copper. They are responsible for backhauling their services NZ went further than most with LLU ‘Naked DSL’ – allows for the exclusive use of the copper Discussion LLU – what does it really mean? * ISP MDF Voice to PSTN DSLAM LAN filter RADIUS Core BRAS MDF Voice to PSTN DSLAM LAN filter P P ATU-R ATU-R h P l P l S ATU-C ATU-C Charles Summers, ADSL Standards, Implementation, and Architecture Figure 2.10 ATU-C: ADSL Transceiver Unit – Central Office ATU-R: ADSL Transceiver Unit – Remote MDF Voice to PSTN DSLAM filter Backhaul MDF Voice to PSTN DSLAM * * *