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WANs and Router Basics

Chapter 1: WANs & Routers

Chapter 2: Router CLI

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Table of Contents

WAN Devices

WAN StandardsWAN Technologies

Router Basics

Router User

Interface

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WAN Devices

Table of Contents

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WAN Services

WANs provide for the exchange of data packets/frames between

routers/bridges and the LANs theysupport.

A WAN interconnects LANs that

are usually separated by largegeographic areas.

WANs connect devices. Such

devices include...

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RoutersRouters offer many servicesincluding:InternetworkingWAN serial interfaces

Routers can operate as...Internal RoutersBackbone Routers

Area Border Routers

Autonomous System Boundary

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WAN Bandwidth Switches

Service provider equipment thatconnects to WAN bandwidth for

voice, data and videocommunications.

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Modems

Also called CSU/DSUs (channelservice units/digital service units)

Interface with voice-gradeconnection in order to convertanalog signal to digital.

Represents the DCE side of theDTE/DCE connection.

More on DTE/DCE later

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Communication Servers

Concentrates dial-in and dial-outservices.

Equipment is usually at the serviceprovider’s site.

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WAN Standards

Table of Contents

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WAN Standards

What layers of the OSI model doWAN standards describe?

Physical and Data Link Layers

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WAN Physical Layer

Protocols that describe how to provideelectrical, mechanical, operational, and

functional connections for WAN services. These services are most often obtained

from WAN service providers such asRBOCs, alternate carriers, post-

telephone, and telegraph (PTT) agencies.Describes the interface between the

data terminal equipment (DTE) and the

data circuit-terminating equipmentDCE .

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WAN Physical Layer

Typically, the DCE is the serviceprovider and the DTE is the

attached device.In this model, the services offeredto the DTE are made availablethrough a modem or a CSU/DSU.

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WAN Physical Layer

Several physical layer standardsspecifying this interface between

the DTE & DCE are...EIA/TIA-232EIA/TIA-449V.24V.35X.21G.703

EIA-530

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WAN Data-Link Layer

WAN data link protocols describehow frames are carried between

systems on a single data link. They include protocols designed tooperate over dedicated point-to-

point, multipoint, and multi-accessswitched services.

WAN standards are defined and

managed by a number of

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WAN Data-Link Encapsulations

High-Level Data Link Control (HDLC)Cisco default encapsulation; typically

used between routers running CiscoIOS; replacing SDLC

Streamlined: no windowing or flowcontrol

may not be compatible with differentvendors because of the way eachvendor has chosen to implement it.

HDLC supports both point-to-point and

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Frame Relayuses high-quality digital facilities;

uses simplified framing with no errorcorrection mechanisms(connectionless!!);

it can send Layer 2 information muchmore rapidly than other WANprotocols

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PPP (Point-to-Point Protocol)Developed by IETF; replacing SLIP

Contains a field to identify thenetwork layer protocol

PPP can check for link quality during

connection establishmentSupports PAP (PasswordAuthentication Protocol) & CHAP(Challenge Handshake Authentication

Protocol)

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WAN Technologies

Table of Contents

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WAN Technologies Overview

Dedicated

• T1, E1, T3,E3

•xDSL

•SONET

Analog

•Dial-upmodems

•Cablemodems

•Wireless

Switched

CircuitSwitched

• POTS

• ISDN

PacketSwitch

ed

• X.25

• Frame

Relay

CellSwitched

• ATM

• SMDS

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Dedicated

• T1, E1, T3,E3

•xDSL

•SONET

Analog

•Dial-upmodems

•Cablemodems

•Wireless

Switched

CircuitSwitched

• POTS

• ISDN

PacketSwitch

ed

• X.25

• Frame

Relay

CellSwitched

• ATM

• SMDS

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Dedicated Digital Services

T series in U.S. and E series inEuropeUses time division multiplexing to“slice up” data and assign time slotsfor transmissions T1 = 1.544 Mbps

T3 = 44.736 Mbps

E1 = 2.048 Mbps

•Uses twisted pair& fiber

•Extremelypopular

•Moderate cost

Dedicated Digital Servicesprovide full-time connectivity

through a point-to-point link

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Digital Subscriber Lines(xDSL); the x stands for a family of

technologiesNew WAN Technology for home use;decreasing bandwidth with increasing

distance from the phone companiesCO.

Data rates as high as 51.84 Mbps butmore common to be in the 100s of

Kbps

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Synchronous Optical Network (SONET)

Specialized high bandwidthtechnology for use at various OpticalCarrier speeds (OC) ranging from51.84 Mbps (OC-1) to 9,952 Mbps (OC-192)

Uses lasers to divide the wavelengthof the light into sections that can carry

large amounts of data (Wave Division

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Dedicated

• T1, E1, T3,E3

•xDSL

•SONET

Analog

•Dial-upmodems

•Cablemodems

•Wireless

Switched

CircuitSwitch

ed

• POTS

• ISDN

PacketSwitch

ed

• X.25

• Frame

Relay

CellSwitched

• ATM

• SMDS

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Analog Services

Dial-up Modems (switchedanalog)

Limited to 56 kbpsWorks with existing phone network

Low cost and widespread usage

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Analog Services

Cable Modems (Shared Analog)Puts data signals on the same cable

as television signalsIncreasing in popularity

Maximum bandwidth can be 10 Mbps,

though this degrades as more usersattach to a given network segment(behaving like an unswitched LAN)

Cost is relatively low; usage is small

but increasing; the medium is coaxial

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Analog Services

Terrestrial

Bandwidthstypically in the 11Mbps range

Cost is relativelylow

Line-of-sight isusually required

Usage is moderate

Satellite

Can serve mobileusers and remoteusers

Usage iswidespread

Cost is very high

Wireless

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Dedicated

• T1, E1, T3,E3

•xDSL

•SONET

Analog

•Dial-upmodems

•Cablemodems

•Wireless

Switched

CircuitSwitch

ed

• POTS

• ISDN

PacketSwitch

ed

• X.25

• Frame

Relay

CellSwitch

ed

• ATM

• SMDS

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Circuit Switched Services

Plain Old Telephone System (POTS)

Not a computer data service but...POTS is an important component of ourcommunication infrastructure and

It is still the standard for designing

reliable networks

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Integrated Services DigitalNetwork (ISDN)

Historically important--first dial-updigital service

Cost is moderate; max. bandwidth =

128 kbps for BRI (Basic Rate Interface)2 B channels @ 64kps and 1 D channel @16kps

B channels are voice/data channels; D for

signaling

B

B

D

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Dedicated

• T1, E1, T3,E3

•xDSL

•SONET

Analog

•Dial-upmodems

•Cablemodems

•Wireless

Switched

CircuitSwitch

ed

• POTS

• ISDN

PacketSwitch

ed

• X.25

• Frame

Relay

CellSwitch

ed

• ATM

• SMDS

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Packet Switched Services

X.25 (Connection-oriented)Older WAN technology developed in

1970sReliable--X.25 has been extensivelydebugged and is now very stable--literally no errors in modern X.25

networksStore & Forward--Since X.25 storesthe whole frame to error check itbefore forwarding it on to the

destination, it has an inherent delay

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Frame Relay (Connectionless)More efficient and much faster than

X.25Packet switched version of ISDN(which is circuit switched); data ratesup to 44.736Mbps with 56kbps and384kbps being the most popular

Used mostly to forward LAN IP and IPXpackets but can be used to forward

other types of traffic

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Dedicated

• T1, E1, T3,E3

•xDSL

•SONET

Analog

•Dial-upmodems

•Cablemodems

•Wireless

Switched

CircuitSwitch

ed

• POTS

• ISDN

PacketSwitch

ed

• X.25

• Frame

Relay

CellSwitch

ed

• ATM

• SMDS

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Cell Switched Services

Asynchronous Transfer Mode (ATM)Relatively new WAN Technology

related to broadband ISDN; max.bandwidth = 622 MbpsDeveloped in order to provide onetechnology for both WANs and LANs to

transport data, video, and voice. (HighCost)Key Benefits:

One network for all traffic--voice, data,video

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Switched Multimegabit DataService (SMDS)

Closely related to ATM; SMDS is theMAN (Metropolitan Area Network)implementation of ATM

High Cost with max. bandwidth44.736 Mbps

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Acronym Name Max. Bandwidth Comments

T1, T3 T1, T3 1.544 & 44.736 Mbps Widely used telecommunications

xDSL Digital Subscriber Line 384 kbps New technology over phone linesSONET

Synchronous Optical

Network9,992 Mbps Very fast optical fiber transmission

Dial-up Modem Modem 56 kbps Mature technology over phone lines

Cable Modem Cable Modem 10 Mbps New technology using cable TV

Terrestrial Wireless Wireless 11 Mbps Microwave and laser links

Satellite Wireless Wireless 2 Mbps Microwave and laser links

POTSPlain Old Telephone

Service4 kHz Analog The Standard for Reliability

ISDNIntegrated Services

Digital Network128 kbps Data and Voice Together

X.25 X.25 An Old Reliable, Workhorse

Frame Relay Frame Relay up to 44.736 Mbps A flexible new workhorse; son of ISDN

ATMAsynchronous

Transfer Mode622 Mbps High powered Networks

SMDS Switched MultimegabitData Service 1.544 & 44.736 Mbps MAN variant of ATM



Analog Services



WAN T ech nolog ies Re view

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Router Basics

Table of Contents

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Internal Components

RAM NVRAM Flash ROM

InterfacesConsole

Auxiliary

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RAM

Temporary storage for routerconfiguration files

RAM content is lost on power downor restart

Stores...

Routing tablesARP cache

Fast switching cache

Packet buffering

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NVRAM

Non-volatile RAM

Stores backup/startup

configuration filesContent is not lost when router ispowered down or restarted.

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Flash

EEPROM (Electronically ErasableProgrammable Read-Only Memory)

Holds the Cisco IOS (InternetOperating System)

Allows updating of software

without replacing the Flash chipMultiple versions of IOS can bestored

Retained on power down

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ROM

Contains POST (Power On Self Test)

A bootstrap program (loads the

Cisco IOS)And operating system softwareBackup, trimmed down version of the

IOSUpgrades require installing new chipset

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Interfaces

Network connections throughwhich packets enter and exit the

routerAttached to the motherboard or asseparate modules.

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Labs

Before moving on to Ch. 3, makesure you have done both of the

required labs for Ch. 2Lab 2.2.2

Lab 2.2.3.2

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Router User Interface

Table of Contents

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User EXEC Modes

User modeLimited mode used for checking the

routers status, looking at routingtables, etc. You cannot configure the routerOnce you’ve typed the password to

enter user mode, you will see the >prompt. The word “Router” will be thename of the router.

Password:

Means you’re in

user mode

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Command Lists

To get a list of commands availablein either user mode or privileged

mode, enter a ? at the prompt.Router> ?

Router# ?

Since the available commands willbe more than the screen can hold,you will get the --More-- messageat the bottom.

Hitting the space bar will advance

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ipflash:interfacesipx version parser

Router# show ?

Getting Help on a Command

The ? can be used with a partialcommand to learn all the availablecommands that match what you

entered. To use this help feature, enter the

partial command, then tap the spacebar, then type ?For example... The Router returned all

the available commands

for “show”

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Error Indicator

When you’ve entered an error inthe command string, a carat (^)

symbol will indicate where the erroroccurred.

For example...Router# show runing-config

^

% Invalid input detected at the ‘^’ marker

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Labs

Before taking the Ch. 2/3 test,make sure you have done both of

the required labs for Ch. 3Lab 3.2.1

Lab 3.2.2

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End Slide Show

Table of Contents

Chapter 02 03

Documents

Transcript of Chapter 02 03