ADSL-Dr.WissamFawaz.pptVIP

* * * * * * * DSL was designed to provide high speed access. * A telephone company technician must install a Network Interface Device on the customer’s permises. This small plastic box marks the end of the telephone company’s property and the start of the customer’s property. Close to the NID is a splitter, that separates the 0-4000 Hz band used by the POTS from data. The POTS signal is routed to the existing telephone or fax machine and the data signal is routed to an ADSL modem. * What it does is to divide the available 1.1 Mhz spectrum on the local loop into 256 independent channels of 4 Khz each. Channel 0 is used for POTS (Plain Old Telephone Service). Channels 1-5 are not used to keep the voice signal and data signals from interfering. The rest are available for user data. In its ADSL version 32 channels are used for upstream and the rest downstream. The ADSL standard allows speeds of as much as 8 Mbps downstream and 1 Mbps in the upstream * * * * * * * * * * * Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge end systems, access networks, links 1.3 Network core circuit switching, packet switching, network structure 1.4 Delay, loss and throughput in packet-switched networks 1.5 Protocol layers, service models 1.6 Networks under attack: security 1.7 History * A closer look at network structure: network edge: applications and hosts access networks, physical media: wired, wireless communication links network core: interconnected routers network of networks * The network edge: end systems (hosts): run application programs e.g. Web, email at “edge of network” client/server peer-peer client/server model client host requests, receives service from always-on server e.g. Web browser/server; email client/server peer-peer model: minimal (or no) use of dedicated servers e.g. Skype, BitTorrent * Access networks and physical media Q: How to connect end systems to edge router? residential access nets institutional access networks (school, company) mobil