PROYECTO FINAL DE CARRERA TÍTULO DEL PFC: Estudio de viabilidad telefonía IP en red inalámbrica UPC TITULACIÓN: Ingeniería Superior de Telecomunicaciones AUTOR: Cristina Jerez Álvarez DIRECTOR: Josep Paradells Aspas Glosario ACK Acknowledgment ADSL Asymmetric Digital Subscriber Line AP Access Point ASCII American Standard Code for Information Interchange ASK Amplitude Shift Keying BBDD Base de Datos BPSK Binary Phase Shift Keying CDMA Code Division Multiple Access DC Direct Current (0 Hz) DNS Domain Name System DSSS Direct Sequence Spread Spectrum DVB Digital Video Broadcasting EAP Extensible Authentication Protocol ETSI European Telecomunication Standard Institute FDM Frequency Division Multiplexing FM Frequency Modulation FSK Frequency Shift Keying GHz Gigahertz GMSK Gaussian Minimum Shift Keying GSM Global System for Mobile communications Hz Hertz HTTP HyperText Transfer Protocol ICI Inter-Carrier Interference ID Identification IEEE Institute of Electrical and Electronic Engineers IFFT Inverse Fast Fourier Transform IMPP Instant Messaging and Presence Protocol IP Internet Protocol IPSec Internet Protocol Security 2 ISDN Integrated Services Digital Network ISM Industrial Scientific Medical ITU International Telecomunication Union kbps Kilo bits per second kHz Kilohertz LDAP Lightweight Directory Access Protocol m Metro MAC Medium Access Control Mbps Mega bits per second MCU Multipoint Control Unit MIME Multipurpose Internet Mail Extensions MHz Megahertz MGC Media Gateway Control MMCC Multimedia Conference Control MOS Mean Opinion Score OFDM Orthogonal Frequency Division Multiplexing PAE Port Access Entity PAP Password Authentication Protocol PBX Private Branch Exchange PC Point Coordinator PCM Pulse Code Modulation PHY Physical Layer PPP Point to Point Procotol PSK Phase Shift Keying PSTN Public Switched Telephone Network QAM Quadrature Amplitude Modulation QoS Quality Of Service RF Radio Frequency RFC Request for Comments RSN Robust Security Network RSNA Robust Security Network Association RSVP ReSerVation Protocol 3 RTP Real-time Transport Protocol RTCP Real-time Control Protocol SCIP Simple Conference Invitation Protocol SCP Service Control Point SCTP Stream Control Transmission Protocol SDP Session Description Protocol SIMPLE SIP for Instant Messaging and Presence Leveraging Extensions SIP Session Initiation Protocol SMTP Simple Mail Transport Protocol SSID Sevice Set ID SSP Service Switching Point STD Standard TCP Transmission Control Protocol TERENEA Trans-European Research and Education Networking Association TKIP Temporal Key Integrity Protocol TLS Transport Layer Security TSN Transitional Security Network TV Television UA User Agent UAC User Agent Client UAS User Agent Server UDP User Datagram Protocol URI Universal Resource Identifier URL Uniform Resource Locator VoIP Voice over IP XSF Xarxa Sense Fils (Red sin Hilos) WPA WiFi Protected Access WEP Wired Equivalent Protocol WiFi Wireless Fidelity WLAN Wireless Local Area Network WRAP Wireless Router Application Platform 4 Índice Glosario ........................................................................................................................ 2 Introducción ................................................................................................................. 7 Capítulo 1 ................................................................................................................... 10 1. Problemática existente ........................................................................................ 10 1.1. Planteamiento del problema ............................................................................... 10 1.2. Justificación ......................................................................................................... 12 1.3. Objetivos ............................................................................................................. 13 1.3.1. Objetivo General ........................................................................................... 13 1.3.2. Objetivos específicos .................................................................................... 13 Capítulo 2 ................................................................................................................... 15 2. Conceptos generales sobre VoIP ......................................................................... 15 2.1. Voz sobre IP (VoIP) .............................................................................................. 15 2.1.1. ¿Qué es Voz sobre IP? ................................................................................... 17 2.1.2. Elementos de red .......................................................................................... 18 2.1.3. Protocolos de VoIP ........................................................................................ 20 2.2. Arquitectura Multimedia de Internet .................................................................. 20 2.2.1. RTP (Real Time Protocol) ............................................................................... 23 2.2.2. RTCP (Real Time Control Protocol) ................................................................ 26 2.2.3. SDP (Session Description Protocol) ............................................................... 26 2.3. SIP (Session Initiation Protocol) ........................................................................... 27 2.3.1. Descripción del protocolo ............................................................................. 27 2.3.2. Agentes SIP ................................................................................................... 31 2.3.3. Protocolo de funcionamiento........................................................................ 33 Capítulo 3 ................................................................................................................... 45 3. Estudio Servicio UPCom (Comunicaciones unificadas en la UPC) ......................... 45 3.1. Que es UPCom .................................................................................................... 45 3.1.1. Situación de partida ...................................................................................... 46 3.1.2. Características de UPCom ............................................................................. 49 Capítulo 4 ................................................................................................................... 51 4. Descripción de escenarios XSF: portal cautivo (eduroam-web) y WPA-TKIP (eduroam) ................................................................................................................... 51 4.1. Redes Inalámbricas: ¿Qué es Wireless? ¿Qué es WiFi? ........................................ 51 4.1.1. Estándar Wireless IEEE802.11 ....................................................................... 52 4.2. ¿Qué es eduroam? .............................................................................................. 53 4.2.1. ¿Cómo funciona? .......................................................................................... 55 4.2.2. ¿Cómo se incorpora eduroam a la XSF? ........................................................ 57 4.2.3. Tipos de acceso a XSF .................................................................................... 57 Capítulo 5 ................................................................................................................... 62 5. Problemática ....................................................................................................... 62 5.1. Búsqueda de terminales ...................................................................................... 65 5.2. Autenticación ...................................................................................................... 72 5.3. NATs.................................................................................................................... 79 5 5.4. Seguridad ............................................................................................................ 84 5.5. Movilidad ............................................................................................................ 84 5.6. QoS ..................................................................................................................... 86 Capítulo 6 ................................................................................................................... 87 6. Soluciones ........................................................................................................... 87 6.1. Características de terminales............................................................................... 87 6.2. Autenticación ...................................................................................................... 88 6.3. NATs.................................................................................................................... 95 6.3.1. Métodos para atravesar NAT y Firewalls. Técnicas y comparativas. .............. 95 6.4. Métodos de seguridad....................................................................................... 101 6.4.1. Autenticación y control de acceso. .............................................................. 101 6.4.2. Cifrado. ....................................................................................................... 104 6.5. Handover entre APs .......................................................................................... 113 6.5.1. RADIUS en AP ............................................................................................