Ch.1 – WANs and Routers CCNA 2 version 3.0 Rick Graziani Cabrillo College

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Rick Graziani 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

Rick Graziani 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.

Rick Graziani 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.

Rick Graziani Introduction to WANs

Rick Graziani Introduction to routers in a WAN Routers connect and allow communication between two networks and determine the best path for data to travel through the connected networks. RAM 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 NVRAM Provides storage for the startup configuration file Retains content when router is powered down or restarted

Rick Graziani Introduction to routers in a WAN Flash memory 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) 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 Interfaces Connect router to network for frame entry and exit Can be on the motherboard or on a separate module

Rick Graziani Router LANs and WANs Smaller broadcast domains Connecting Layer 3 networks

Rick Graziani 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.

Rick Graziani 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.

Rick Graziani 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.

Rick Graziani 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).

Rick Graziani Router internal components CPU RAM Flash NVRAM Buses ROM Interfaces Power Supply

Rick Graziani Router physical characteristics

Rick Graziani Router external connections

Rick Graziani Management port connections

Rick Graziani Management port connections

Rick Graziani Connecting console interfaces When connected using the console interface, the computer is acting as a “dumb terminal”.

Rick Graziani Connecting console interfaces

Rick Graziani Connecting console interfaces

Rick Graziani Connecting LAN interfaces

Rick Graziani Connecting WAN interfaces

Rick Graziani Connecting WAN interfaces

Rick Graziani Connecting WAN interfaces

Rick Graziani Summary An understanding of the following key points should have been achieved: WAN and LAN concepts Role of a router in WANs and LANs WAN protocols Configuring encapsulation The identification and 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