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CCNA 2 Module 1 WANs and Routers

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Objectives

• Upon completion of this module, the student will be able to perform tasks related to the following:

• WANs

• Routers

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Introduction to WANs

• A wide-area network (WAN) is a data communications network spanning a large geographic area such as a state, province, or country.

• They use the services of carriers.

• 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.

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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.

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WAN Devices

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WAN Services

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Data Link Encapsulations

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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.

• Routers need the Internetwork Operating System software (IOS) to run configuration files.

• The main internal components of the router are random access memory (RAM), nonvolatile random-access memory (NVRAM), flash memory, read-only memory (ROM), and interfaces.

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RAM

•Stores routing tables

•Holds ARP cache and 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

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NVRAM

• Provides storage for the startup configuration file

• Retains content when router is powered down or restarted

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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)

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ROM

• Maintains instruction 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

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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

• While a router can be used to segment LANs, its major use is as a WAN device.

• Routers have both LAN and WAN interfaces

• WAN technologies are frequently used to connect routers and these routers communicate with each other by WAN connections.

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Router LANs and WANs

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Router LANs and WANs

Routers are the backbone devices of large intranets and of the Internet.

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Router LANs and WANs

• Two main functions of a router are the selection of best path 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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Segmentation with Routers

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WAN Physical Layer

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WAN Data Link Layer Protocols

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WAN Standards and Protocols

WAN physical layer standards and protocols: • EIA/TIA-232 • EIA/TIA-449 • V.24 • V.35 • X.21 • G.703 • EIA-530 • ISDN • T1, T3, E1, and E3 • xDSL • SONET

WAN data link layer standards and protocols:    • High-level data link control (HDLC) • Frame Relay • Point-to-Point Protocol (PPP) • Synchronous Data Link Control

(SDLC) • Serial Line Internet Protocol (SLIP) • X.25 • ATM • LAPB • LAPD • LAPF

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Internal Components of a 2600 Router

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External Connections on a 2600 Router

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Router External Connections

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Computer or Terminal Console Connection

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Modem Connection to Console or Auxiliary Port

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Connecting Console Interfaces

1. Configure terminal emulation software on the PC for the following:

The appropriate com port

9600 baud

8 data bits

1 stop bit

No parity

No flow control

2. Connect a rollover cable to the router console port (RJ-45 connector).

3. Connect the other end of the rollover cable to the RJ-45 to DB-9 adapter

4. Attach the female DB-9 adapter to a PC.

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Connecting Router LAN Interfaces

• A router is usually connected to a LAN through an Ethernet or Fast Ethernet interface.

• The router is a host that communicates with the LAN through a hub or a switch.

• A straight-through cable is used to make this connection. A 10BASE-TX or 100BASE-TX router interface requires

• Category 5, or better, unshielded twisted-pair (UTP) cable, regardless of the router type

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Connecting Router Interfaces

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Router Serial WAN Connectors

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Router Serial WAN Connectors

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DCE Serial Connections

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Summary