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Module 1

Module 1. WANs and Routers. 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

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Module 1

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  1. Module 1 WANs and Routers

  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 CCNA 2 Version 3.0

  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. CCNA 2 Version 3.0

  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 with Integrated Services Digital Network (ISDN) services. • Communication servers concentrate dial-in and dial-out user communication. CCNA 2 Version 3.0

  5. Introduction to WANs There are different layer 2 encapsulation types – Cisco’s serial interfaces default to Cisco HDLC CCNA 2 Version 3.0

  6. Physical Layer Standards CCNA 2 Version 3.0

  7. Data Link Layer CCNA 2 Version 3.0

  8. CSU/DSU and Digital Local Loops • The communications link needs signals in an appropriate format. • The Channel Service Unit (CSU) receives and transmits signals from and to the WAN line and provides a barrier for electrical interference from either side of the unit. The CSU can also echo loopback signals from the phone company for testing purposes. • The Data Service Unit (DSU) manages line control, and converts input and output between RS-232C, RS-449, or V.xx frames from the LAN and the time-division multiplexed (TDM) DSX frames on the T-1 line. The DSU manages timing errors and signal regeneration. The DSU provides a modem-like interface between the computer as Data Terminal Equipment (DTE) and the CSU. CCNA 2 Version 3.0

  9. CCNA 2 Version 3.0

  10. The CSU/DSU may also be built into the interface card of the router. CCNA 2 Version 3.0

  11. 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 CCNA 2 Version 3.0

  12. 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 CCNA 2 Version 3.0

  13. Router LANs and WANs • Smaller broadcast domains • Connecting Layer 3 networks CCNA 2 Version 3.0

  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. CCNA 2 Version 3.0

  15. 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. CCNA 2 Version 3.0

  16. Router Role in a WAN • The primary WAN role of a router is 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. CCNA 2 Version 3.0

  17. 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). CCNA 2 Version 3.0

  18. Router Internal Components • CPU • RAM • Flash • NVRAM • Buses • ROM • Interfaces • Power Supply CCNA 2 Version 3.0

  19. Router Physical Characteristics CCNA 2 Version 3.0

  20. Router External Connections CCNA 2 Version 3.0

  21. Management Port Connections CCNA 2 Version 3.0

  22. Management Port Connections CCNA 2 Version 3.0

  23. Connecting Console Interfaces When connected using the console interface, the computer is acting as a “dumb terminal”. The PC can at the same time be connected to the router via its NIC – then it is part of the network <Router Output> CCNA 2 Version 3.0

  24. Connecting Console Interfaces CCNA 2 Version 3.0

  25. Connecting Console Interfaces <Router Output> CCNA 2 Version 3.0

  26. Connecting LAN Interfaces CCNA 2 Version 3.0

  27. Connecting WAN Interfaces CCNA 2 Version 3.0

  28. Connecting WAN Interfaces CCNA 2 Version 3.0

  29. Connecting WAN interfaces CCNA 2 Version 3.0

  30. 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 • Encapsulation Types • 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 CCNA 2 Version 3.0

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