Tài liệu học CCNA kỳ 2 mod1 wansrouters

1 Module 1 – WANs and Routers NIIT-ICT Hanoi info@niithanoi.vn 2 Overview Students completing this module should be able to: • Identify organizations responsible for WAN standards • Explain the difference between a WAN and LAN and the type of addresses each uses • Describe the role of a router in a WAN • Identify internal components of the router and describe their functions • Describe the physical characteristics of the router • Identify common ports on a router • Properly connect Ethernet, serial WAN, and console ports 2 NIIT-ICT Hanoi info@niithanoi.vn 3 Introduction to WANs These are the major characteristics of WANs: • They connect devices that are separated by wide geographical areas. • They use the services of carriers such as the Regional Bell Operating Companies (RBOCs), Sprint, MCI, VPM Internet Services, Inc., and Altantes.net. • They use serial connections of various types to access bandwidth over large geographic areas. NIIT-ICT Hanoi info@niithanoi.vn 4 Introduction to WANs -A WAN differs from a LAN in several ways. For example, unlike a LAN, which connects workstations, peripherals, terminals, and other devices in a single building or other small geographic area, a WAN makes data connections across a broad geographic area. Companies use a WAN to connect various company sites so that information can be exchanged between distant offices. - A WAN operates at the physical layer and the data link layer of the OSI reference model. It interconnects LANs that are usually separated by large geographic areas. WANs provide for the exchange of data packets and frames between routers and switches and the LANs they support. 3 NIIT-ICT Hanoi info@niithanoi.vn 5 Introduction to WANs • Routers offer many services, including internetworking and WAN interface ports. • Switches in the WAN provide connectivity for voice, data, and video communication. • Modems include interface voice-grade services, channel service units/digital service units (CSU/DSUs) that interface T1/E1 services, and Terminal Adapters/Network Termination 1 (TA/NT1s) that interface Integrated Services Digital Network (ISDN) services. • Communication servers concentrate dial-in and dial-out user communication. NIIT-ICT Hanoi info@niithanoi.vn 6 Introduction to WANs • WAN data link protocols describe how frames are carried between systems on a single data link. • They include protocols designed to operate over dedicated point-to-point, multipoint, and multi-access switched services such as Frame Relay. • WAN standards are defined and managed by a number of recognized authorities, including the following agencies: – International Telecommunication Union-Telecommunication Standardization Sector (ITU-T), formerly the Consultative Committee for International Telegraph and Telephone (CCITT). – International Organization for Standardization (ISO). – Internet Engineering Task Force (IETF). – Electronic Industries Association (EIA). 4 NIIT-ICT Hanoi info@niithanoi.vn 7 Router Introduction • A router is a special type of computer. It has the same basic components as a standard desktop PC. It has a CPU, memory, a system bus, and various input/output interfaces. • Just as computers need operating systems to run software applications, routers need the Internetwork Operating System software (IOS) to run configuration files. NIIT-ICT Hanoi info@niithanoi.vn 8 RAM Random Access Memory RAM, also called dynamic RAM (DRAM), has the following characteristics and functions: Stores routing tables Holds ARP cache Holds fast-switching cache Performs packet buffering (shared RAM) Maintains packet-hold queues Provides temporary memory for the configuration file of the router while the router is powered on Loses content when router is powered down or restarted 5 NIIT-ICT Hanoi info@niithanoi.vn 9 NVRAM Non-Volatile RAM NVRAM has the following characteristics and functions: Provides storage for the startup configuration file Retains content when router is powered down or restarted NIIT-ICT Hanoi info@niithanoi.vn 10 Flash Flash memory has the following characteristics and functions: Holds the operating system image (IOS) Allows software to be updated without removing and replacing chips on the processor Retains content when router is powered down or restarted Can store multiple versions of IOS software Is a type of electronically erasable, programmable ROM (EEPROM) 6 NIIT-ICT Hanoi info@niithanoi.vn 11 ROM Read-Only Memory Read-only memory (ROM) has the following characteristics and functions: Maintains instructions for power-on self test (POST) diagnostics Stores bootstrap program and basic operating system software Requires replacing pluggable chips on the motherboard for software upgrades NIIT-ICT Hanoi info@niithanoi.vn 12 Interfaces Interfaces have the following characteristics and functions: Connect router to network for frame entry and exit Can be on the motherboard or on a separate module 7 NIIT-ICT Hanoi info@niithanoi.vn 13 Router LANs and WANs • Smaller broadcast domains • Connecting Layer 3 networks NIIT-ICT Hanoi info@niithanoi.vn 14 Router LANs and WANs • Routers are the backbone devices of large intranets and of the Internet. • They operate at Layer 3 of the OSI model, making decisions based on network addresses. • The two main functions of a router are the selection of best path for and the switching of frames to the proper interface. • Routers accomplish this by building routing tables and exchanging network information with other routers. 8 NIIT-ICT Hanoi info@niithanoi.vn 15 WAN & OSI model Physical Layer Data Link Layer OSI model WAN Specifications SMDS X21 bis EIA/TIA-232 EIA/TIA-449 V24 V35 HSSI G.703 EIA-530 LAPB Frame Relay X25 PLP HDLC PPP SDLC MAC sublayer Network Layer NIIT-ICT Hanoi info@niithanoi.vn 16 Router role in a WAN • The WAN physical layer describes the interface between the data terminal equipment (DTE) and the data circuit-terminating equipment (DCE). • Generally, the DCE is the service provider and the DTE is the attached device. In this model, the services offered to the DTE are made available through a modem or a CSU/DSU. EIA/TIA-232, EIA/TIA-449, V.24, V.35, X.21, G.703, EIA-530, ISDN, T1, T3, E1, and E3, xDSL, SONET (OC-3, OC-12, OC-48, OC-192) , 9 NIIT-ICT Hanoi info@niithanoi.vn 17 External CSU/DSU • For digital lines, a channel service unit (CSU) and a data service unit (DSU) are required. – We won’t go into the differences here. • The two are often combined into a single piece of equipment, called the CSU/DSU. To router To T1 circuit NIIT-ICT Hanoi info@niithanoi.vn 18 Router role in a WAN • The primary WAN roles of a router are therefore not routing, but providing connections to and between the various WAN physical and data-link standards. • For example, a router may have an ISDN interface using PPP encapsulation and a serial interface terminating a T1 line using Frame Relay encapsulation. HDLC, Frame Relay, PPP, SDLC, SLIP, X.25, ATM, LAPB, LAPD, LAPF, 10 NIIT-ICT Hanoi info@niithanoi.vn 19 Academy approach to hands-on labs • In the academy lab, devices that make up the WAN cloud are simulated by the connection between the back-to-back DTE-DCE cables. • One of the routers will provide the clock rate (later). NIIT-ICT Hanoi info@niithanoi.vn 20 Router physical characteristics [...]... info@niithanoi.vn 21 Management port connections NIIT-ICT Hanoi info@niithanoi.vn 22 11 Management port connections router modem modem terminal NIIT-ICT Hanoi info@niithanoi.vn 23 Connecting console interfaces When connected using the console interface, the computer is acting as a “dumb terminal” NIIT-ICT Hanoi info@niithanoi.vn 24 12 Connecting console interfaces NIIT-ICT Hanoi info@niithanoi.vn 25 ... console interfaces 9600 baud 8 data bits No parity 1 stop bit No flow control roll-over cable router NIIT-ICT Hanoi info@niithanoi.vn terminal 26 13 Connecting LAN interfaces NIIT-ICT Hanoi info@niithanoi.vn 27 Connecting WAN interfaces NIIT-ICT Hanoi info@niithanoi.vn 28 14 Connecting WAN interfaces • What is the type of connection to the Cisco device? Cisco routers may use different connectors for the... difference between these two is that the DCE device provides the clock signal for the communications on the bus The device documentation should specify whether it is DTE or DCE NIIT-ICT Hanoi info@niithanoi.vn 29 Connecting WAN interfaces What signaling standard does the device require? For each different device, a different serial standard could be used Each standard defines the signals on the cable and specifies... description of the internal components of a router • The physical characteristics of a router • The common ports on a router • How to connect router console, LAN, and WAN ports NIIT-ICT Hanoi info@niithanoi.vn 32 16