ADSL & PPPoE & RADIUS

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Content 1, Introduction 3 2, Overview 3 3,ADSL 4 3,1 The principle of the signal transmitting 4 3,2 The physical issues of signal transmission 5 3,3 Proposed modulation formats for ADSL 5 3,3,1 The modulation technique 5 3,3,1,1 Frequency modulation 5 3,3,1,2 Amplitude modulation 6 3,3,1,3 Phase modulation 6 3,3,2 Three different modulation of ADSL 6 3,3,2,1 QAM – Quadrature Amplitude modulation 6 3,3,2,2 CAP – Carrierless Amplitude phase 7 3,3,2,3 DMT – Discrete multi tone (multi carrier modulation) 7 3,4 The xDSL 8 4,PPPoE 10 4, 1 Introduction 10 4, 2 Two phases of PPPoE 10 4,2,1 PPPoE Discovery 11 4,2,2 PPPoE session 12 4,3,PPPoE Security Considerations 14 4,4,The data flower 14 4,5 The Experiment of the PPPoE 15 5 RADIUS 16 5,1 Introduce 16 5,1 Operations 17 5,3 RADIUS Security Considerations 18 6 Reference 19 2
1, Introduction Asymmetric Digital Subscriber Lines (ADSL) is used to deliver high-rate digital data over existing ordinary phone-lines. This makes it possible for all the users who use phone line and modem to connect the Internet to get the cheap and rapid solution. And it also keeps the original familiar operation interface. There are some inconsistent targets for the modem internet connection: not only to connect remote multi-users host via a connection device, but also to provide some functionalities such connection control, fee calculation and reduce the configuration for the users. The PPPOE Protocol and RADIUS Protocol are to resolve the issues above. PPPoE (PPP over Ethernet) is a Point to Point protocol on the Ethernet which is created after 1998. For the connection control and fee calculation, Remote Authentication Dial In User Service (RADIUS) will provide. In the paper,I will describe the relationships among the three parts, the principle of each part and the running mode of them in detail. I will show an implementation based on the Point to Point protocol via Ethernet under Linux OS. And some samples to connect the Internet via ADSL. 2, Overview Why we use ADSL today? The most cost-effective method to connect multiple hosts to the customer premise access device is via Ethernet. It is important to require little or no configuration on the end user side while keeping the cost of this device as low as possible. By combining two standards, Ethernet and PPP, into PPP over Ethernet (PPPoE), it is required of the end user only to set up standard dial-up Internet access. The PPPoE solution uses existing PC hardware and software, existing Ethernet NICs, and existing ADSL/DSL modems. It requires no special configuration or additions to the customer premise modem or ADSL/DSL access network. It requires no special wire for the high-speed networks and services. Actually ADSL is fit into the existing equipment and operation system with little disruption to ongoing subscriber services. A user places a telephone call to establish physical layer connectivity. The voice signal and the data signal will be departed via “Splitter”. The “Splitter” will modulate the signal from ADSL Modem to high frequency signal. In this way, the ADSL and ISBN can be used with phone at the same time. Using Dial-Up Networking in Windows, the user makes a connection to the ISP via an ADSL/DSL access device (modem). ISPs are accustomed to providing consumer Internet access through PPP sessions. PPP can be easily adapted to broadband services with no changes to the existing protocol. When the ISPs began to prepare their networks for the 3
Page 1: ADSL & PPPoE & RADIUS Seminar paper
Page 5 and 6: 3,ADSL Figure 2: The ADSL in the OS
Page 7 and 8: one. But if we delay the sending of
Page 9 and 10: modulation techniques,xDSL can be d
Page 11 and 12: PPPoE, defined in RFC 2516 (“A Me
Page 13 and 14: session that needs to be terminated
Page 15 and 16: transferred directly via TCP/IP sta
Page 17 and 18: RADIUS (Remote Authentication Diali
Page 19: 6 Reference R. Stevens, TCP/IP Illu

ADSL & PPPoE & RADIUS

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