Chapter 2: Connecting to the WAN Connecting Networks

Chapter Introduction 2.1 WAN Technologies Overview 2.2 Selecting a WAN Technology 2.3 Summary

2.1 WAN Technologies Overview

Purpose of WANs Why Choose a WAN? WANs propojují na velké vzdálenosti propojují LANs mezi sebou využívají služby jiných, např. telefon, kabel, satelit, ISP používají sériové propojení

 Stages of business growth TermínVýznamPříklad Small office Campus Branch Distributed Malá kancelář Areál Pobočky v různých městech Rozptýlený, s pobočkami po celém světě Učebna TVP ISŠ Auto Lukáš Cisco Purpose of WANs

 Stages of business growth 1. Small office Purpose of WANs

 Stages of business growth 2. Campus Purpose of WANs

 Stages of business growth 3. Branch Purpose of WANs

 Stages of business growth 4. Distributed Purpose of WANs

 Cisco Enterprise Architectures Organizační jednotky, které zajišťují jednotlivé činnosti Purpose of WANs

 Cisco Enterprise Architectures Příklad topologie Purpose of WANs

WAN Technology Concepts  WAN functions and the OSI Reference Model Většina činností WAN se odehrává na vrstvách 1 a 2. Zařízení WAN většinou slouží jako málo inteligentní propojení mezi vzdálenými místy. Zařízení vyšších vrstev (např. routery) využívají WAN jen k tomu, aby po nich něco poslaly.

 WAN physical layer concepts WAN Technology Concepts

 WAN physical layer concepts WAN Technology Concepts Public Switched Telephone Network

 WAN data link layer protocols WAN Technology Concepts Spojení dvou bodů, vyhrazené jen jim, napořád. Jako poštovní služby: doručuje balíčky. Ty mohou chodit i různými cestami a dojít i v jiném pořadí, než byly poslány. Jako telefon. Po dobu hovoru jsou body spojeny linkou, jejíž konfigurace se nemění.

 Switching technologies used for WANs WAN Technology Concepts Jako poštovní služby: doručuje balíčky. Ty mohou chodit i různými cestami a dojít i v jiném pořadí, než byly poslány. Jako telefon. Po dobu hovoru jsou body spojeny linkou, jejíž konfigurace se nemění.

2.2 Selecting a WAN Technology

WAN Services WAN Link Connection Options

WAN Services Service-Provided Network Infrastructure

Private WAN Infrastructures Leased Lines Advantages:  Simplicity  Quality  Availability Disadvantages:  Cost  Limited flexibility

 Dedicated Links: Leased line services Private WAN Infrastructures Leased Lines

Private WAN Infrastructures Dialup Advantages:  Simplicity  Availability  Low implementation cost Disadvantages:  Low data rates  Long connection time

 Circuit switching options Basic Rate Interface Primary Rate Interface Public Switched Telephone Network Private WAN Infrastructures ISDN

Private WAN Infrastructures Frame Relay Nesou datový i hlasový provoz. Žádné kontroly ani řízení => malé zpoždění. Stálé virtuální obvody (PVC = Permanent Virtual Circuits) jsou identifikovány pomocí DLCI = Data-Link Connection Identifier. Když R1 posílá na R2, hodí to na DLCI = 102. Když R2 posílá na R1, hodí to na DLCI = 201. Jedna linka může mít na každém konci jiný identifikátor.

 Packet switching options: Frame Relay Private WAN Infrastructures Frame Relay

Private WAN Infrastructures ATM Built on a cell-based architecture, rather than on a frame-based architecture. ATM cells are always a fixed length of 53 bytes. Rychlost až 622Mb/s i více. Data přepravuje v malých cells (buňkách) o délce 53B = 5B hlavička + 48B => málo starostí, malé zpoždění => hodí se pro hlas, video

Private WAN Infrastructures Ethernet WAN Ethernet dříve nebyl použitelný na velké vzdálenosti. Např. kabel UTP nemůže být delší než 100 m. Ale moderní optické kabely mohou překonat desítky km. Proto poskytovatelé začali používat Ethernet např. pro spojení v rámci města. Varianty:  Metropolitan Ethernet (MetroE)  Ethernet over MPLS (EoMPLS)  Virtual Private LAN Service (VPLS) Výhody: menší náklady snadná integrace s dosavadními sítěmi větší výkon, produktivita

Private WAN Infrastructures MPLS Multiprotocol Label Switching (MPLS) is a multiprotocol high- performance WAN technology that directs data from one router to the next, based on short path labels rather than IP network addresses.

Private WAN Infrastructures VSAT Very small aperture terminal (VSAT) – obousměrné spojení přes satelit.

Private WAN Infrastructures DSL  Always-on connection technology that uses existing twisted-pair telephone lines to transport high- bandwidth data, and provides IP services to subscribers.  A DSL modem converts an Ethernet signal from the user device to a DSL signal, which is transmitted to the central office.

Private WAN Infrastructures Cable  Network access is available from some cable television networks.  Cable modems provide an always- on connection and a simple installation.

Private WAN Infrastructures Wireless New developments in broadband wireless technology:  Municipal Wi-Fi – Many cities have begun setting up municipal wireless  WiMAX – Worldwide Interoperability for Microwave Access (WiMAX) is a new technology that is just beginning to come into use.  Satellite Internet

Private WAN Infrastructures 3G/4G Cellular Common cellular industry terms include:  3G/4G Wireless – Abbreviation for 3rd generation and 4th generation cellular access. These technologies support wireless Internet access.  Long-Term Evolution (LTE) – A newer and faster technology, considered to be part of the 4th generation (4G) technology.

Private WAN Infrastructures VPN Technology VPN is an encrypted connection between private networks over a public network. Benefits:  Cost savings  Security  Scalability  Compatibility with broadband technology Two types of VPN:  Site-to-site VPNs  Remote-access VPNs

Selecting WAN Services Choosing a WAN Link Connection Answer the following questions when choosing a WAN Connection:  What is the purpose of the WAN?  What is the geographic scope?  What are the traffic requirements?

Selecting WAN Services Choosing a WAN Link Connection

© 2008 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID Summary

Chapter 2: Summary  A business can use private lines or the public network infrastructure for WAN connections.  WAN access standards operate at layers 1 and 2 of the OSI model, and are defined and managed by the TIA/EIA, ISO, and IEEE.  A WAN may be circuit-switched or packet-switched.  There is common terminology used to identify the physical components of WAN connections and who, the service provider or the customer, is responsible for which components.  Service provider networks are complex and the service provider’s backbone networks consist primarily of high-bandwidth fiber optic media.

Chapter 2: Summary (cont.)  Permanent, dedicated point-to-point connections are provided by using leased lines.  Public infrastructure connections include DSL, cable, wireless, and 3G/4G cellular.  Security over public infrastructure connections can be provided by using remote-access or site-to-site VPNs.

Presentation_ID 40 © 2008 Cisco Systems, Inc. All rights reserved.Cisco Confidential