Sistemas Tecnológicos Sesión Nro. 3. Las Redes de Computadoras

Redes  Es un grupo de dispositivos, como por ejemplo los computadores, las impresoras, los concentradores (hubs), los conmutadores (switches), y otros componentes de hardware, que est á n conectados entre s í y pueden comunicarse con la finalidad de compartir: –Datos –Aplicaciones –Recursos.  Seg ú n su alcance geogr á fico se clasifican en: –WAN (Wide Area Network) –MAN (Metropolitan Area Network) –LAN (Local Area Network)

Red privada generalmente contenida dentro de un edificio o en un espacio de tamaño reducido a unos pocos kilómetros cuadrados. Las LANs son diferenciadas principalmente por tres características:  Su tamaño  Su tecnología de transmisión  Su topología Observaciones: Basadas en canales tipo “broadcast” (Uno envía, todos escuchan) Usualmente están conectadas a redes de grandes áreas (WANs) utilizando compuertas (Gateways) Velocidades entre 10 y 1000 Mbps Ejemplos: Ethernet, Fast Ethernet, Anillo FDDI, ATM LANs. Redes LAN

Definen la disposición física de los componentes de una LAN Topología BUS Topología Estrella Topología Anillo Topología Mixta Topologías de Redes

Red que cubre el área geográfica de una ciudad (varios Kms. cuadrados). Características:  Basado en tecnología LAN  Soporta data, voz y video  Ejemplos: TV por cable, Internet por Cable  Estándar IEEE DQDB (Distributed Queue Dual Bus) Redes MAN

Redes WAN  Red que cubre extensas áreas geográficas (Países, continentes).  Esta compuesta por un conjunto de computadoras denominadas Hosts. – Estos Hosts están conectados por una subnet. – A cada extremo de la subnet se encuentran elementos de conexión denominados Switches o Routers que la interconecta con otras subnets.  La conexión entre routers se efectúa a través de lineas de comunicación que generalmente son propiedad de compañias telefónicas o de telecomunicaciones.

Networking Elements Network Interface Card (NIC) Network Operating System (NOS)

Networking Elements Hub, Switch Cables / Medios de Transmisión UTP Coaxial Fibra Óptica

More Local Users and Remote Users Internet Resources and Commerce New Applications and Computers Challenges Driving The Business

Ethernet Operation

Layer 3 Layer 2 Layer 1 Level of Intelligence and Complexity Hubs, Switches, Routers  Increase performance  Decrease cost  Secure the environment

Hubs—Layer 1

Switches—Layer 2 MAC Port Address Table XXX1Port 1 XXX2Port 6 XXX3Port 8 Virtual Connections Memory Switch

Routers—Layer 3 Network FDDI Network Frame Relay Remote Location Network Ethernet Routing Table Frame Relay Ethernet FDDI

Network Congestion  Too many users in a single collision domain  Bandwidth-intensive applications such as publishing, CAD/CAM, and imaging  Networked applications such as support automation software  More servers and high- performance PCs More Users Internet Access Networked Applications High Bandwidth Applications

… Mejorando el Performance Shared Ethernet 10 Switched Ethernet 10 Shared Fast Ethernet 100 Switched Fast Ethernet 100

Segmentación con Switched Ethernet Switched Ethernet Cada Nodo tiene 10 Mbps Backbone Switched Ethernet 10

Shared Fast Ethernet Todos los Nodos Comparten 100 Mbps Backbone Shared Fast Ethernet 100

Swicthed Fast Ethernet Switched Fast-Ethernet Cada Nodo tiene 100 Mbps Backbone Switched Fast Ethernet 100

Why Fast Ethernet?  It’s Fast! –Ten times the speed of Ethernet  It’s Simple! –No re-training for MIS and LAN administrators –Runs same applications as today’s 10BASE-T –Uses existing cabling infrastructure –Familiar network management tools  It’s Affordable! –Just twice the price of 10Mps Ethernet –No extra or ‘hidden’ costs Fast Ethernet is Ethernet — Only Faster!

Fast Ethernet Applications 10Mb Segments, 100Mb Servers 10 Mb Hubs 10/100 Switch 100 Mb Hub 10Mb Segments, 100Mb Downlinks and Servers 100 Mb Hub 100 Mb Switch 10/100 Switch

Fast Ethernet Applications Private 10Mb Desktops, 100Mb Downlinks & Servers 100 Mb Switch 10/100 Switches Shared 100Mb to the Desktop 100 Mb Switch 100 Mb Hubs 100 Mb Hub

Deploying 100BASE-T... Peak vs. Aggregate Bandwidth Problem: Aggregate Bandwidth Solution: 10/100 Switching Problem: Peak Bandwidth Solution: 100Mbps Workgroup High performance systems with EISA or PCI bus Slow response on large file transfers Bursty traffic Large workgroup Standard end systems with ISA bus Continuous loading Excessive collisions Eliminates server bottlenecks and scaleable to large networks BUT peak workstation bandwidth still only 10Mbps Improves peak performance, but end stations need 100Mbps cards Switching further increases aggregate bandwidth ?? ?? 10/100 Switch 100 Mb Repeater

Switching or Fast Ethernet to the Desktop Fast EthernetSwitched Ethernet Existing Workgroups New Workgroups Seldom makes sense  Most existing PCs cannot take advantage of 100 Mb  High cost - adapter change Obvious upgrade path  Low cost  Leverages existing PCs  No cable change  Multimedia capable For power users - peak bandwidth needs  Ideal for PCI and EISA PCs, Unix workstations  Only slightly higher cost  Easy migration with 10/100 adapters For office automation - aggregate bandwidth  Lower cost  Clear choice for ISA PCs  Standard Ethernet cable

Understanding Migration Issues  Can my cabling support high-speed networking technologies?  How do I boost performance with minimum cost and disruption to users?  What happens to replaced equipment—can I use it someplace else?  How familiar am I with the new technology—do I need to re-train my staff before an upgrade?