Ch.1 – WANs and Routers

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

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 Rick Graziani graziani@cabrillo.edu

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. Rick Graziani graziani@cabrillo.edu

4. 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 graziani@cabrillo.edu

5. Introduction to WANs Rick Graziani graziani@cabrillo.edu

6. 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 graziani@cabrillo.edu

7. 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 graziani@cabrillo.edu

8. Router LANs and WANs • Smaller broadcast domains • Connecting Layer 3 networks Rick Graziani graziani@cabrillo.edu

9. 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 graziani@cabrillo.edu

10. 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 graziani@cabrillo.edu

11. 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 graziani@cabrillo.edu

12. 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 graziani@cabrillo.edu

13. Router internal components • CPU • RAM • Flash • NVRAM • Buses • ROM • Interfaces • Power Supply Rick Graziani graziani@cabrillo.edu

14. Router physical characteristics Rick Graziani graziani@cabrillo.edu

15. Router external connections Rick Graziani graziani@cabrillo.edu

16. Management port connections Rick Graziani graziani@cabrillo.edu

17. Management port connections Rick Graziani graziani@cabrillo.edu

18. Connecting console interfaces When connected using the console interface, the computer is acting as a “dumb terminal”. <Router Output> Rick Graziani graziani@cabrillo.edu

19. Connecting console interfaces Rick Graziani graziani@cabrillo.edu

20. Connecting console interfaces <Router Output> Rick Graziani graziani@cabrillo.edu

21. Connecting LAN interfaces Rick Graziani graziani@cabrillo.edu

22. Connecting WAN interfaces Rick Graziani graziani@cabrillo.edu

23. Connecting WAN interfaces Rick Graziani graziani@cabrillo.edu

24. Connecting WAN interfaces Rick Graziani graziani@cabrillo.edu

25. 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 Rick Graziani graziani@cabrillo.edu