Describing-DSL-Technology课件

Slide Title,Body Text,Second Level,Third Level,Fourth Level,Fifth Level,Cisco Network Academy. All rights reserved.,.,CCNP+ ISCW v1.0,Teleworker Connectivity,Describing DSL Technology,DSL Features,What Is a DSL?,Utilizes high transmission frequencies (up to 1 MHz),Technology for delivering high bandwidth over regular copper lines,Connection between subscriber and CO,What Is a DSL? (Cont.),Downstream and upstream transmission,下行与上行的不同的速率的传输,.,Symmetrical and asymmetrical services,对称与不对称的服务,.,Multiple xDSL variations,多种,DSL,的技术,Can deliver data along with voice (voice over IP),可以同时使用,VOIP,的技术实现语音的传输,Always-on data connection,持续在线的连接,Bandwidth versus distance,距离越远带宽越低,DSL Variants,DSL variants differ in:,Nature,种类（异步或同步）,Maximum data rate,最大的数据传输速率,Line coding technology,线路编码技术,Data and voice support,对数据和语音的支持,Maximum distance,最大传输距离,DSL Variants Examples,DSL Technology,Nature,Max. Data Rate (Down / Up) bps,Data and POTS,ADSL,Asymmetric,8 M / 1 M,Yes,VDSL,Symmetric / Asymmetric,52 M / 13 M,Yes,IDSL,Symmetric,144 k / 144 k,No,SDSL,Symmetric,768 k / 768 k,No,HDSL,Symmetric,2 M / 2 M,No,G.SHDSL,Symmetric,2.3 M / 2.3 M,No,DSL Limitations,DSL Distance Limitations,Maximum data rate and distance assume no impairments.,Maximum data rate is achieved at shortest distance.,Maximum distance is achieved at lowest data rate.,DSL Technology,Max. Data Rate(Down / Up) bps,Max. Distancefeet / km,ADSL,8 M / 1 M,18,000 / 5.46,VDSL,52 M / 13 M,4,500 / 1.37,IDSL,144 k / 144 k,18,000 / 5.46,SDSL,768 k / 768 k,22,000 / 6.7,G.SHDSL,2.3 M / 2.3 M,28,000 / 8.52,ADSL,ADSL (Cont.),ADSL equipment:,ADSL terminal unit-remote (ATU-R),ADSL terminal unit-central office (ATU-C),ADSL features three basic line-coding techniques:,Single carrierCAP modulation,Multicarrier with DMT,Multicarrier with G.lite,ADSL operation and performance is influenced by different impairments.,ADSL and POTS Coexistence,A key feature of ADSL is coexistence with POTS.,Transmission of voice and data signals is performed on the same wire pair.,Data circuits are offloaded from the voice switch.,ADSL and POTS Coexistence (Cont.),Splitter versus microfilter,How are data and POTS channels separated?,POTS splitter at CO,Microfilters at customer premises,CAP Modulation,Single-carrier modulation technique,DMT Modulation,Multiple-carrier modulation technique,Data over ADSL: PPPoE,Data over ADSL,IP packets encapsulated over ATM,Three major approaches:,RFC 1483/2684 Bridged,PPPoE,PPPoA,PPP over Ethernet,Ethernet frame carrying PPP frame,Service provider end:,DSLAM for DSL connection termination,Aggregation router for PPP session termination,Subscriber end:,DSL modem for DSL connection termination,PPPoE client for PPP session termination,The client device is the PC or the router at the CPE,PPPoE Session Variables,DSL and PPPoE deployment types:,Router terminating DSL and with PPPoE client,Modem terminating DSL and router with PPPoE client,Modem terminating DSL and end-user PC with PPPoE client,PPPoE Session Establishment,PPP session is from PPPoE client to the aggregation router.,Subscriber IP address is assigned by the aggregation router via IPCP.,Data over ADSL: PPPoA,PPP over ATM (Cont.),CPE receives an IP address via IPCP like in the dial model.,Summary,DSL is a family of access technologies for delivering high bandwidth over regular copper lines at limited distances.,In regards to the downstream and upstream, the DSL can be symmetrical or asymmetrical.,DSL variants are ADSL, HDSL, RADSL, SDSL, IDSL, VDSL, and G.SHDSL.,The trade-off among various DSL types is distance versus speed.,Different impairments influence the achieved operational speed.,