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Tema 1: Redes de acceso a Internet. PowerPoint Presentation
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Tema 1: Redes de acceso a Internet.

Tema 1: Redes de acceso a Internet.

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Tema 1: Redes de acceso a Internet.

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  1. Tema 1: Redes de acceso a Internet. Estructura de Internet MPLS Tecnologías cableadas Digital Subscriber Line (xDSL) Cable Broadband Service Broadband Over Power Lines Fiber Tecnologías inalámbricas Satellite Wireless 3G

  2. router workstation server mobile local ISP regional ISP company network A “nuts and bolts” view of a network • Millions of connected computing devices: hosts, end-systems • pc’s workstations, servers • PDA’s phones, toasters running network apps • communication links • fiber, copper, radio, satellite • routers: forward packets (chunks) of data thru network • protocols: control sending, receiving of msgs • TCP, IP, and HTTP, FTP, PPP, …

  3. A closer look at the network structure • The network edge: applications and hosts • The network core: • routers • network of networks • The access networks and physical media: communication links

  4. local ISP local ISP NAP NAP Internet structure: network of networks • Roughly hierarchical • National/international backbone providers (NBPs) • e.g. BBN/GTE, Sprint, AT&T, IBM, UUNet • interconnect (peer) with each other privately, or at public Network Access Point (NAPs) • A point of presence (POP) is a machine that is connected to the Internet. • Internet Service Providers (ISPs) provide dial-up or direct access to POPs. • regional ISPs • connect into NBPs • local ISP, company • connect into regional ISPs regional ISP NBP B NBP A regional ISP

  5. Network Access Points (NAPs) Note: Peers in this context are commercial backbones. Source:

  6. MCI/WorldCom/UUNET Global Backbone Source:

  7. The situation in Europe See: Also: More about technolgies:

  8. Hierarchical Routing • aggregate routers into regions, “autonomous systems” (AS) • routers in same AS run same routing protocol • “intra-AS” routing protocol • routers in different AS can run different intra-AS routing protocol • Gateway router • Direct link to router in another AS

  9. forwarding table configured by both intra- and inter-AS routing algorithm intra-AS sets entries for internal dests inter-AS & intra-As sets entries for external dests 3a 3b 2a AS3 AS2 1a 2c AS1 2b 3c 1b 1d 1c Inter-AS Routing algorithm Intra-AS Routing algorithm Forwarding table Interconnected ASes

  10. Intra-AS Routing • also known as Interior Gateway Protocols (IGP) • most common Intra-AS routing protocols: • RIP: Routing Information Protocol • OSPF: Open Shortest Path First • IGRP: Interior Gateway Routing Protocol (Cisco proprietary)

  11. Internet inter-AS routing: BGP • BGP (Border Gateway Protocol): the de facto standard • BGP provides each AS a means to: • Obtain subnet reachability information from neighboring ASs. • Propagate reachability information to all AS-internal routers. • Determine “good” routes to subnets based on reachability information and policy. • allows subnet to advertise its existence to rest of Internet: “I am here”

  12. Why MPLS? • Integrate best of Layer 2 and Layer 3 • Intelligence of IP Routing • performance of high-speed switching • Legacy service transport • QoS • VPN Semantics • Link layers include: • Ethernet, PoS, ATM, FR Note: MPLS and IP could be optimal solution for overall IP Services Architecture.

  13. MPLS as a Foundation for Value Added Services VPNs Traffic Engineering IP+ATM IP+Optical GMPLS Any Transport Over MPLS MPLS Network Infrastructure

  14. General Context (CE) – Customer Edge • At Edge (ingress): • Classify packets • Label them • In Core: Forward using labels (as opposed to IP addr) Label indicates service class and destination Edge Label Switch Router Label Switch Router (LSR) (PE) – Provider Edge (P) – Provider Label Distribution Protocol (LDP/TDP, RSVP,BGP) • At Edge (egress): • Remove Label (PE) – Provider Edge

  15. RIB Routing Process LIB FIB LFIB Control and Forward Plane Separation Route Updates/ Adjacency Control Plane Label Bind Updates/ Adjacency MPLS Process Data Plane MPLS Traffic IP Traffic

  16. MPLS Example: Routing Information Out I’face OutLabel Out I’face OutLabel Out I’face OutLabel In Label Address Prefix In Label Address Prefix In Label Address Prefix 128.89 1 128.89 0 128.89 0 171.69 1 171.69 1 … … … … … … 128.89 0 0 1 You Can Reach 128.89 Thru Me You Can Reach 128.89 and 171.69 Thru Me 1 Routing Updates (OSPF, EIGRP, …) 171.69 You Can Reach 171.69 Thru Me

  17. MPLS Example: Assigning Labels Out I’face Out I’face Out I’face In Label Address Prefix In Label Address Prefix In Label Address Prefix OutLabel OutLabel OutLabel - 128.89 1 4 4 128.89 0 9 9 128.89 0 - - 171.69 1 5 5 171.69 1 7 … … … … … … … … … … … … 128.89 0 0 1 Use Label 9 for 128.89 1 Use Label 4 for 128.89 and Use Label 5 for 171.69 Label Distribution Protocol (LDP) (downstream allocation) 171.69 Use Label 7 for 171.69

  18. MPLS Example: Forwarding Packets Out I’face Out I’face Out I’face In Label Address Prefix In Label Address Prefix In Label Address Prefix OutLabel OutLabel OutLabel - 128.89 1 4 4 128.89 0 9 9 128.89 0 - - 171.69 1 5 5 171.69 1 7 … … … … … … … … … … … … MPLS network egress point 128.89 0 0 1 Data 9 Data 1 Data 4 Data Label Switch Forwards Based on Label

  19. Un ejemplo: ONO

  20. Un ejemplo: ONO

  21. Un ejemplo: ONO

  22. Tecnologías cableadas de acceso time UMTS 2010 SHDSL BPON VDSL UDSL 2005 SDSL HSCSD ADSL GPRS HDSL EDGE PMP 2000 2B1Q CDMA VoD GSM DECT TV digital PDC STM 1 WLAN Voice 4B3T 1995 CDMA OPAL Power line POTS Bluetooth TV VSAT ISDN AMPS AON PON 1990 xDSL TV analog WLL Cellular radio Satellite 1980 Wireless Coax Fiber optics Copper 1975 Copper 1900

  23. Implantación de las diversas tecnologías

  24. What is xDSL • DSL: Digital Subscriber Line • DSL as a transmission technology using the existing copper wires between a central exchange and a customer with a bit rate speed up to 26 Mbit/s • Signals: symmetrical/asymmetrical, digital, text, audio, video • Concepts of local loop, management, handshake, interoperability, scalability, legacy

  25. Why x-DSL • Faster than analog (56 kbit/s) and ISDN (>128 kbit/s) modems, reasonable cost, reach 3-6 km • Less expensive that E1/T1 systems, 1.5-2.0- Mbit/s, reach 1 km • Use already existing copper pairs (depending on the performance): start as equipments installed. • Transforms potential 700 millions copper wires installed worldwide into multimegabit data pipes • Scenario convenient to providers and users immediately available • Enable the management of different providers of different services to different users tipology • Alternative: Optical access • Wait for full availability • current cost • better performance

  26. How it works • Remove line components limiting the bandwidth to the voice frequency (4 KHz = 64 Kbit/s) • Use of copper low attenuation frequencies sending more bits x Hertz for longer reach • Use higher bit rate with a low increase of signal rate (baud) in the line • Use of line codes allowing the transmission of 2 to 15 bits x Hertz (up to 1.1, 2.2, 12 MHz) • Adoption of techniques/phylosophies limiting negative effects (crosstalk, echo, spectrum, etc.)

  27. VPI 18, VCI 23, PCR 256/128 Kb/s VPI 18, VCI 31, PCR 512/256 Kb/s VPI 18, VCI 37, PCR 2048/300 Kb/s Circuito permanente ATM Arquitectura de una red ADSL Red ATM Red telefónica DSLAM (ATU-C) Internet Router-modem ADSL (ATU-R) Ethernet 10BASE-T Bucle de abonado (conexión ADSL) Enlace ATM OC-3 (155 Mb/s)

  28. DSLAM Digital subscriber line access multiplexer • A Digital Subscriber Line Access Multiplexer (DSLAM) allows telephone lines to make faster connections to the Internet. • It is a network device, located near the customer's location, that connects multiple customer Digital Subscriber Lines (DSLs) to a high-speed Internet backbone line using multiplexing techniques. • By locating DSLAMs at locations remote to the telephone company central office (CO), telephone companies are now providing DSL service to consumers who previously did not live close enough for the technology to work.

  29. ADSL G.Lite (ITU G.992.2) • ADSL requiere instalar en casa del usuario un filtro de frecuencias o ‘splitter’ (teléfono de ADSL). • El splitter aumenta el costo de instalación y limita el desarrollo. • ADSL G.Lite suprime el splitter. También se llama ADSL Universal, ADSL ‘splitterless’ o CADSL (Consumer ADSL). • Sin splitter hay más interferencias, sobre todo a altas frecuencias.

  30. ADSL2 versus ADSL (G.992.3 x G.992.1) • 2nd generation of ADSL with improvements on: • Loop-reach increase for equivalent bit rates (300m) • Higher down/up bit rates • loop diagnostics • Adjustable spectrum shaping during operat/initializ • Power vs traffic control: L0(full),L1, L2 • robustness against loop impairments and RFI • Improved multivendor interoperability • Improved application support for an all digital mode of operation and voice over ADSL operation;

  31. ADSL 2+ : G.992.5 • Performance • Increase downstream: to 16 Mbit/s • Maybe increase in upstream (Oct. 2003) • Increase reach (1.5 - 3 Km) • ADSL+ doubles the bandwidth (from 1.1 to 2.2 MHz) with a significant increase of data rates on short loops • Backwards compatibility (needs G.992.3)

  32. VDSL (Very high speed DSL) • Es el ‘super-ADSL’. Permite capacidades muy grandes en distancias muy cortas. • Las distancias y caudales en sentido descendente son: • 300 m 51,84 – 55,2 Mb/s • 1000 m 25,92 – 27,6 Mb/s • 1500 m 12,96 – 13,8 Mb/s • En ascendente se barajan tres alternativas: • 1,6 – 2,3 Mb/s • 19,2 Mb/s • Igual que en descendente (simétrico)

  33. Cable Broadband Service • Developed for TV distribution • Evolved to provide TV/Data/Voice • Up to 15 Mbs download; 2 Mbs upload • Distance independent • Register w/ FCC Cable Modem

  34. Hybrid Fiber/Coax (HFC) CATV Network

  35. Residential access networks: cable modems Diagram:

  36. Gigabit Passive Optical Network (GPON) Fiber to the Home Architecture Central Office Passive Outside Plant Multi-dwelling units Typically up to 20 km (28 dB) Edge router (data, video) 2.5 Gbps @ 1490 nm splitters points Small/medium enterprises 1.2 Gbps @ 1310 nm Optical Line Terminal (OLT) Optional 1,550 nm to support local analog/digital video if required Single family homes Softswitch (for voice) Optical Network Terminal (ONT) Source: Fiber to the Home Council

  37. Objetivos • Soporte de todos los servicios: voz (TDM, tanto SONET como SDH), Ethernet (10/100 BaseT), ATM,… • Alcance máximo de 20 Km, aunque el estándar se ha preparado para que pueda llegar hasta los 60 km. • Soporte de varios bitrate con el mismo protocolo, incluyendo velocidades simétricas de 622 Mb/s, 1.25 Gb/s, y asimétricas de 2.5 Gb/s en el enlace descendente y 1.25 Gb/s en el ascendente. • El número máximo de usuarios que pueden colgar de una misma fibra es 64 (el sistema está preparado para dar hasta 128).

  38. Futuro de GPON • GPON no requiere de dispositivos electrónicos u opto-electrónicos activos para la conexión entre el abonado y el operador, y por lo tanto supone una inversión y unos costes de mantenimiento menores • La mayoría de los grandes operadores actuales se han decantado por la tecnología GPON. • En 2007 muchas operadoras han realizado “pruebas piloto” con pocos usuarios. El objetivo de estas pruebas es empezar a vislumbrar las dificultades de trabajar la fibra óptica. • A lo largo de 2008 se espera el lanzamiento “masivo” de servicios sobre GPON.

  39. Coupler Repeater Power Generation Plant Backhaul Point (Gateway) In some Access implementations, these physical links are replaced by wireless links Access BPL Internet Low Voltage Aggregation Point BPL signals are extracted here & converted into/from traditional communication packets for appropriate communication direction High Voltage MediumVoltage Broadband Over Power Lines ~ 1kVolts to 40 kVolts ~ MVolts ~ 120/240 Volts LV Distribution Transformer Substation Power Line Interface Device Located In Home

  40. Tecnología PLC: Principios básicos Una idea sencilla: Acondicionar la red eléctrica para la transmisión simultánea de las señales de baja frecuencia (50/60 Hz) para transmisión de energía y alta frecuencia (1-40 MHz) para transmisión de datos Red de Acceso PLC Principios básicos • La Red Eléctrica es un medio hostil para la transmisión de datos: derivaciones, malas conexiones, ruido, impedancia variable... • Modulaciones robustas: DSSS, GMSK, OFDM • No existe ningún estándar, sino un grupo de sistemas diferentes e incompatibles entre sí • Velocidades de transmisión de hasta 200 Mbps compartidos entre los usuarios, y dependiendo de la configuración • Enchufe eléctrico (Toma única de alimentación, voz y datos.) • Permite seguir prestando el suministro eléctrico sin ningún problema • Simetría del ancho de banda Baja Tensión (BT) Media Tensión (MT) Conexión a otros operadores CT2 CT1 Terminal Punto Interconexión CT3 Repetidor CT4 HE 100 – 300 hogares HE: Equipo PLC en CT CTn Repetidor (Instalado en el Cuarto de Contadores) CT5 Terminal (Instalado en Casa de Cliente) CT6 CT: Centro de Transformación MT/BT

  41. El uso de la red eléctrica existente: La principal ventaja de la tecnología PLC y su máximo condicionante Tecnología PLC: Principios básicos Ventajas • Permite gestión y control en Tiempo Real • Bi-direccional • Aprovecha la infraestructura eléctrica: • Alta disponibilidad (Red de MT mallada) • Mejora mantenimiento preventivo (medio físico compartido) • Rapidez de instalación • Coste moderado • Total independencia de: • Obra Civil y licencias • Licencias radio • Interferencias • Operadores TELCOM (Internos / Externos) Desventajas • Variable en el tiempo • Ruido elevado • Altas atenuaciones • Múltiples reflexiones Densidad Espectral de Media Tensión

  42. Tecnologías inalámbricas de red

  43. Basics of Satellites • Two Stations on Earth want to communicate through radio broadcast but are too far away to use conventional means. • The two stations can use a satellite as a relay station for their communication • One Earth Station sends a transmission to the satellite. This is called a Uplink. • The satellite Transponder converts the signal and sends it down to the second earth station. This is called a Downlink.

  44. Basics: Advantages of Satellites • The advantages of satellite communication over terrestrial communication are: • The coverage area of a satellite greatly exceeds that of a terrestrial system. • Transmission cost of a satellite is independent of the distance from the center of the coverage area. • Satellite to Satellite communication is very precise. • Higher Bandwidths are available for use.

  45. Basics: Disadvantages of Satellites • The disadvantages of satellite communication: • Launching satellites into orbit is costly. • Satellite bandwidth is gradually becoming used up. • There is a larger propagation delay in satellite communication than in terrestrial communication.

  46. Basics: How Satellites are used • Service Types • Fixed Service Satellites (FSS) • Example: Point to Point Communication • Broadcast Service Satellites (BSS) • Example: Satellite Television/Radio • Also called Direct Broadcast Service (DBS). • Mobile Service Satellites (MSS) • Example: Satellite Phones

  47. Types of Satellites • Satellite Orbits • GEO • LEO • MEO • Molniya Orbit • HAPs • Frequency Bands

  48. Geostationary Earth Orbit (GEO) • These satellites are in orbit 35,863 km above the earth’s surface along the equator. • Objects in Geostationary orbit revolve around the earth at the same speed as the earth rotates. This means GEO satellites remain in the same position relative to the surface of earth. • Advantages • A GEO satellite’s distance from earth gives it a large coverage area, almost a fourth of the earth’s surface. • GEO satellites have a 24 hour view of a particular area. • These factors make it ideal for satellite broadcast and other multipoint applications. • Disadvantages • A GEO satellite’s distance also cause it to have both a comparatively weak signal and a time delay in the signal, which is bad for point to point communication. • GEO satellites, centered above the equator, have difficulty broadcasting signals to near polar regions

  49. Frequency Bands • Different kinds of satellites use different frequency bands. • L–Band: 1 to 2 GHz, used by MSS • S-Band: 2 to 4 GHz, used by MSS, NASA, deep space research • C-Band: 4 to 8 GHz, used by FSS • X-Band: 8 to 12.5 GHz, used by FSS and in terrestrial imaging, ex: military and meteorological satellites • Ku-Band: 12.5 to 18 GHz: used by FSS and BSS (DBS) • K-Band: 18 to 26.5 GHz: used by FSS and BSS • Ka-Band: 26.5 to 40 GHz: used by FSS

  50. Satellite: anexample • Ofertas de Telefónica España