ch.1 – wans and routers ccna 2 version 3.0 rick graziani cabrillo college
TRANSCRIPT
Ch.1 – WANs and Routers
CCNA 2 version 3.0
Rick Graziani
Cabrillo College
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Note to instructors
• If you have downloaded this presentation from the Cisco Networking Academy Community FTP Center, this may not be my latest version of this PowerPoint.
• For the latest PowerPoints for all my CCNA, CCNP, and Wireless classes, please go to my web site:
http://www.cabrillo.cc.ca.us/~rgraziani/• The username is cisco and the password is perlman for all of
my materials.
• If you have any questions on any of my materials or the curriculum, please feel free to email me at [email protected] (I really don’t mind helping.) Also, if you run across any typos or errors in my presentations, please let me know.
• I will add “(Updated – date)” next to each presentation on my web site that has been updated since these have been uploaded to the FTP center.
Thanks! Rick
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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
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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.
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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.
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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
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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
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Router LANs and WANs
• Smaller broadcast domains
• Connecting Layer 3 networks
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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.
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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.
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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.
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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).
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Router internal components
• CPU • RAM • Flash • NVRAM
• Buses • ROM • Interfaces • Power Supply
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Connecting console interfaces
When connected using the console interface, the computer is acting as a “dumb terminal”.
<Router Output>
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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