Institute of Technology Sligo - Dept of Computing WANs and Router Basics Semester 2 Chapter 2: WANs & Routers Chapter 3: Router CLI Paul Flynn

Institute of Technology Sligo - Dept of Computing

WANs and Router BasicsWANs and Router Basics

Semester 2Semester 2

Chapter 2: WANs & RoutersChapter 2: WANs & Routers

Chapter 3: Router CLIChapter 3: Router CLIPaul Flynn


Table of ContentsTable of Contents WAN DevicesWAN Devices

WAN StandardsWAN Standards

WAN TechnologiesWAN Technologies

Router BasicsRouter Basics

Router User Router User InterfaceInterface


WAN DevicesWAN Devices


WAN ServicesWAN Services WANs provide for the exchange of data WANs provide for the exchange of data

packets/frames between routers/bridges packets/frames between routers/bridges and the LANs they support. and the LANs they support.

A WAN interconnects LANs that are A WAN interconnects LANs that are usually separated by large geographic usually separated by large geographic areas. areas.

WANs connect devices. Such devices WANs connect devices. Such devices include...include...


RoutersRouters Routers offer many services including:Routers offer many services including:

InternetworkingInternetworking WAN serial interfacesWAN serial interfaces

Routers can operate as...Routers can operate as... Internal RoutersInternal Routers Backbone Routers Backbone Routers Area Border RoutersArea Border Routers Autonomous System Boundary RoutersAutonomous System Boundary Routers


WAN Bandwidth SwitchesWAN Bandwidth Switches

Service provider equipment that connects Service provider equipment that connects to WAN bandwidth for voice, data and to WAN bandwidth for voice, data and video communications.video communications.


ModemsModems

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

Interface with voice-grade connection in Interface with voice-grade connection in order to convert analog signal to digital.order to convert analog signal to digital.

Represents the DCE side of the DTE/DCE Represents the DCE side of the DTE/DCE connection.connection.

More on DTE/DCE laterMore on DTE/DCE later


Communication ServersCommunication Servers

Concentrates dial-in and dial-out services.Concentrates dial-in and dial-out services. Equipment is usually at the service Equipment is usually at the service

provider’s site.provider’s site.





What layers of the OSI model do WAN What layers of the OSI model do WAN standards describe?standards describe? Physical and Data Link LayersPhysical and Data Link Layers


WAN Physical LayerWAN Physical Layer Protocols that describe how to provide electrical, Protocols that describe how to provide electrical,

mechanical, operational, and functional mechanical, operational, and functional connections for WAN services. connections for WAN services.

These services are most often obtained from These services are most often obtained from WAN service providers such as RBOCs, WAN service providers such as RBOCs, alternate carriers, post-telephone, and telegraph alternate carriers, post-telephone, and telegraph (PTT) agencies. (PTT) agencies.

Describes the interface between the data Describes the interface between the data terminal equipment (DTE) and the data circuit-terminal equipment (DTE) and the data circuit-terminating equipment (DCE).terminating equipment (DCE).


WAN Physical LayerWAN Physical Layer Typically, the DCE is the service provider and Typically, the DCE is the service provider and

the DTE is the attached device. the DTE is the attached device. In this model, the services offered to the DTE In this model, the services offered to the DTE

are made available through a modem or a are made available through a modem or a CSU/DSU.CSU/DSU.


WAN Physical LayerWAN Physical Layer Several physical layer standards specifying this Several physical layer standards specifying this

interface between the DTE & DCE are... interface between the DTE & DCE are... EIA/TIA-232 EIA/TIA-232 EIA/TIA-449 EIA/TIA-449 V.24 V.24 V.35 V.35 X.21 X.21 G.703 G.703 EIA-530 EIA-530


WAN Data-Link LayerWAN Data-Link Layer WAN data link protocols describe how frames WAN data link protocols describe how frames

are carried between systems on a single data are carried between systems on a single data link. link.

They include protocols designed to operate over They include protocols designed to operate over dedicated point-to-point, multipoint, and multi-dedicated point-to-point, multipoint, and multi-access switched services. access switched services.

WAN standards are defined and managed by a WAN standards are defined and managed by a number of recognized authorities, including the number of recognized authorities, including the following agencies: ITU-T, ISO, IETF, & EIAfollowing agencies: ITU-T, ISO, IETF, & EIA


WAN Data-Link EncapsulationsWAN Data-Link Encapsulations High-Level Data Link Control (HDLC) High-Level Data Link Control (HDLC)

Cisco default encapsulation; typically used Cisco default encapsulation; typically used between routers running Cisco IOS; between routers running Cisco IOS; replacing SDLCreplacing SDLC

Streamlined: no windowing or flow control Streamlined: no windowing or flow control may not be compatible with different vendors may not be compatible with different vendors

because of the way each vendor has chosen because of the way each vendor has chosen to implement it. to implement it.

HDLC supports both point-to-point and HDLC supports both point-to-point and multipoint configurations with minimal multipoint configurations with minimal overhead overhead


WAN Data-Link EncapsulationsWAN Data-Link Encapsulations

Frame Relay Frame Relay uses high-quality digital facilities; uses high-quality digital facilities; uses simplified framing with no error uses simplified framing with no error

correction mechanisms (connectionless!!);correction mechanisms (connectionless!!); it can send Layer 2 information much more it can send Layer 2 information much more

rapidly than other WAN protocols rapidly than other WAN protocols


WAN Data-Link EncapsulationsWAN Data-Link Encapsulations PPP (Point-to-Point Protocol)PPP (Point-to-Point Protocol)

Developed by IETF; replacing SLIPDeveloped by IETF; replacing SLIP Contains a field to identify the network layer Contains a field to identify the network layer

protocolprotocol PPP can check for link quality during PPP can check for link quality during

connection establishmentconnection establishment Supports PAP (Password Authentication Supports PAP (Password Authentication

Protocol) & CHAP (Challenge Handshake Protocol) & CHAP (Challenge Handshake Authentication Protocol)Authentication Protocol)


WAN TechnologiesWAN Technologies


WAN Technologies WAN Technologies OverviewOverview

Dedicated• T1, E1, T3, E3• xDSL• SONET

Analog• Dial-up modems• Cable modems• Wireless

Switched

Circuit Switched

• POTS• ISDN

Packet Switched

• X.25• Frame Relay

Cell Switched• ATM• SMDS





Switched

Circuit Switched

• POTS• ISDN

Packet Switched




Dedicated Digital ServicesDedicated Digital Services

T seriesT series in U.S. and in U.S. and E seriesE series in Europe in Europe Uses time division multiplexing to “slice up” Uses time division multiplexing to “slice up”

data and assign time slots for transmissionsdata and assign time slots for transmissions T1 = 1.544 MbpsT1 = 1.544 Mbps T3 = 44.736 MbpsT3 = 44.736 Mbps E1 = 2.048 MbpsE1 = 2.048 Mbps E3 = 34.368 MbpsE3 = 34.368 Mbps

•Uses twisted pair & fiber•Extremely popular•Moderate cost

Dedicated Digital Services provide full-time connectivity through a point-to-point link


Dedicated Digital ServicesDedicated Digital Services Digital Subscriber Lines (xDSL)Digital Subscriber Lines (xDSL);; the x stands the x stands

for a family of technologiesfor a family of technologies New WAN Technology for home use; decreasing New WAN Technology for home use; decreasing

bandwidth with increasing distance from the phone bandwidth with increasing distance from the phone companies CO.companies CO.

Data rates as high as 51.84 Mbps but more common Data rates as high as 51.84 Mbps but more common to be in the 100s of Kbpsto be in the 100s of Kbps

Varieties include HDSL, SDSL, ADSL, & VDSLVarieties include HDSL, SDSL, ADSL, & VDSL Moderate expense and getting cheaperModerate expense and getting cheaper


Dedicated Digital ServicesDedicated Digital Services Synchronous Optical NetworkSynchronous Optical Network (SONET) (SONET)

Specialized high bandwidth technology for use at Specialized high bandwidth technology for use at various Optical Carrier speeds (OC) ranging from various Optical Carrier speeds (OC) ranging from 51.84 Mbps (OC-1) to 9,952 Mbps (OC-192)51.84 Mbps (OC-1) to 9,952 Mbps (OC-192)

Uses lasers to divide the wavelength of the light into Uses lasers to divide the wavelength of the light into sections that can carry large amounts of data (Wave sections that can carry large amounts of data (Wave Division Multiplexing)Division Multiplexing)

Very expensive; used by large ISPs and other Internet Very expensive; used by large ISPs and other Internet backbone entities.backbone entities.





Switched

Circuit Switched

• POTS• ISDN

Packet Switched




Analog ServicesAnalog Services

Dial-up ModemsDial-up Modems (switched analog) (switched analog) Limited to 56 kbpsLimited to 56 kbps Works with existing phone networkWorks with existing phone network Low cost and widespread usage Low cost and widespread usage


Analog ServicesAnalog Services Cable ModemsCable Modems (Shared Analog) (Shared Analog)

Puts data signals on the same cable as television Puts data signals on the same cable as television signalssignals

Increasing in popularity Increasing in popularity Maximum bandwidth can be 10 Mbps, though this Maximum bandwidth can be 10 Mbps, though this

degrades as more users attach to a given network degrades as more users attach to a given network segment (behaving like an unswitched LAN)segment (behaving like an unswitched LAN)

Cost is relatively low; usage is small but increasing; Cost is relatively low; usage is small but increasing; the medium is coaxial cable. the medium is coaxial cable.


Analog ServicesAnalog Services

TerrestrialTerrestrial Bandwidths typically in Bandwidths typically in

the 11 Mbps range the 11 Mbps range Cost is relatively lowCost is relatively low Line-of-sight is usually Line-of-sight is usually

requiredrequired Usage is moderate Usage is moderate

SatelliteSatellite Can serve mobile Can serve mobile

users and remote users and remote usersusers

Usage is widespreadUsage is widespread Cost is very highCost is very high

Wireless





Switched

Circuit Switched

• POTS• ISDN

Packet Switched




Circuit Switched ServicesCircuit Switched Services

Plain Old Telephone SystemPlain Old Telephone System (POTS) (POTS) NotNot a computer data service but... a computer data service but...

POTS is an important component of our POTS is an important component of our communication infrastructure andcommunication infrastructure and

It is still the standard for designing reliable It is still the standard for designing reliable networksnetworks


Circuit Switched ServicesCircuit Switched Services Integrated Services Digital NetworkIntegrated Services Digital Network

(ISDN)(ISDN) Historically important--first dial-up digital Historically important--first dial-up digital

serviceservice Cost is moderate; max. bandwidth = 128 kbps Cost is moderate; max. bandwidth = 128 kbps

for BRI (Basic Rate Interface)for BRI (Basic Rate Interface) 2 B channels @ 64kps and 1 D channel @ 16kps2 B channels @ 64kps and 1 D channel @ 16kps B channels are voice/data channels; D for B channels are voice/data channels; D for

signalingsignalingB

B

D





Switched

Circuit Switched

• POTS• ISDN

Packet Switched




Packet Switched ServicesPacket Switched Services X.25X.25 (Connection-oriented) (Connection-oriented)

Older WAN technology developed in 1970sOlder WAN technology developed in 1970s ReliableReliable--X.25 has been extensively debugged and is --X.25 has been extensively debugged and is

now very stable--literally no errors in modern X.25 now very stable--literally no errors in modern X.25 networksnetworks

Store & ForwardStore & Forward--Since X.25 stores the whole frame --Since X.25 stores the whole frame to error check it before forwarding it on to the to error check it before forwarding it on to the destination, it has an inherent delay (unlike Frame destination, it has an inherent delay (unlike Frame Relay) and requires large, expensive memory Relay) and requires large, expensive memory buffering capabilities.buffering capabilities.


Packet Switched ServicesPacket Switched Services Frame RelayFrame Relay (Connectionless) (Connectionless)

More efficient and much faster than X.25More efficient and much faster than X.25 Packet switched version of ISDN (which is circuit Packet switched version of ISDN (which is circuit

switched); data rates up to 44.736Mbps with 56kbps switched); data rates up to 44.736Mbps with 56kbps and 384kbps being the most popularand 384kbps being the most popular

Used mostly to forward LAN IP and IPX packets but Used mostly to forward LAN IP and IPX packets but can be used to forward other types of trafficcan be used to forward other types of traffic

Primary competitive advantage is its low costPrimary competitive advantage is its low cost





Switched

Circuit Switched

• POTS• ISDN

Packet Switched




Cell Switched ServicesCell Switched Services Asynchronous Transfer ModeAsynchronous Transfer Mode (ATM) (ATM)

Relatively new WAN Technology related to Relatively new WAN Technology related to broadband ISDN; max. bandwidth = 622 Mbpsbroadband ISDN; max. bandwidth = 622 Mbps

Developed in order to provide one technology for Developed in order to provide one technology for both WANs and LANs to transport data, video, and both WANs and LANs to transport data, video, and voice. (High Cost)voice. (High Cost)

Key Benefits:Key Benefits: One network for all traffic--voice, data, videoOne network for all traffic--voice, data, video Compatible with current wiring infrastructure (cable plant)Compatible with current wiring infrastructure (cable plant) Very flexible and scalableVery flexible and scalable Simplifies network managementSimplifies network management


Cell Switched ServicesCell Switched Services

Switched Multimegabit Data ServiceSwitched Multimegabit Data Service (SMDS)(SMDS) Closely related to ATM; SMDS is the MAN Closely related to ATM; SMDS is the MAN

(Metropolitan Area Network) implementation (Metropolitan Area Network) implementation of ATMof ATM

High Cost with max. bandwidth 44.736 MbpsHigh Cost with max. bandwidth 44.736 Mbps


Acronym Name Max. Bandwidth Comments

T1, T3 T1, T3 1.544 & 44.736 Mbps Widely used telecommunicationsxDSL Digital Subscriber Line 384 kbps New technology over phone lines

SONETSynchronous Optical Network

9,992 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 Service

4 kHz Analog The Standard for Reliability

ISDNIntegrated Services Digital Network

128 kbps Data and Voice Together

X.25 X.25 An Old Reliable, WorkhorseFrame Relay Frame Relay up to 44.736 Mbps A flexible new workhorse; son of ISDN

ATMAsynchronous Transfer Mode

622 Mbps High powered Networks

SMDSSwitched Multimegabit Data Service

1.544 & 44.736 Mbps MAN variant of ATM

Cell Switched Services

Dedicated Digital Services

Analog Services

Circuit Switched Services

Packet Switched Services

WAN Technologies Review


Router BasicsRouter Basics


Internal ComponentsInternal Components

RAM NVRAM Flash ROM

InterfacesConsoleAuxiliary


RAMRAM Temporary storage for router configuration filesTemporary storage for router configuration files RAM content is lost on power down or restartRAM content is lost on power down or restart Stores...Stores...

Routing tablesRouting tables ARP cacheARP cache Fast switching cacheFast switching cache Packet bufferingPacket buffering And Packet hold queuesAnd Packet hold queues


NVRAMNVRAM

Non-volatile RAMNon-volatile RAM Stores backup/startup configuration filesStores backup/startup configuration files Content is Content is notnot lost when router is powered lost when router is powered

down or restarted.down or restarted.


FlashFlash EEPROM (Electronically Erasable EEPROM (Electronically Erasable

Programmable Read-Only Memory)Programmable Read-Only Memory) Holds the Cisco IOS (Internet Operating Holds the Cisco IOS (Internet Operating

System)System) Allows updating of software without Allows updating of software without

replacing the Flash chipreplacing the Flash chip Multiple versions of IOS can be storedMultiple versions of IOS can be stored Retained on power downRetained on power down


ROMROM

Contains POST (Power On Self Test)Contains POST (Power On Self Test) A bootstrap program (loads the Cisco IOS)A bootstrap program (loads the Cisco IOS) And operating system softwareAnd operating system software

Backup, trimmed down version of the IOSBackup, trimmed down version of the IOS Upgrades require installing new chip setUpgrades require installing new chip set


InterfacesInterfaces

Network connections through which Network connections through which packets enter and exit the routerpackets enter and exit the router

Attached to the motherboard or as Attached to the motherboard or as separate modules.separate modules.


LabsLabs

Before moving on to Ch. 3, make sure you Before moving on to Ch. 3, make sure you have done both of the required labs for have done both of the required labs for Ch. 2Ch. 2 Lab 2.2.2Lab 2.2.2 Lab 2.2.3.2Lab 2.2.3.2


Router User InterfaceRouter User Interface


User EXEC ModesUser EXEC Modes User modeUser mode

Limited mode used for checking the routers status, Limited mode used for checking the routers status, looking at routing tables, etc.looking at routing tables, etc.

You You cannotcannot configure the router configure the router Once you’ve typed the password to enter user mode, Once you’ve typed the password to enter user mode,

you will see the > prompt. The word “Router” will be you will see the > prompt. The word “Router” will be the name of the router.the name of the router.

Password:Password:RouterRouter>> Means you’re in

user mode


Privileged EXEC ModesPrivileged EXEC Modes Privileged modePrivileged mode

Does everything User mode doesDoes everything User mode does Full power to configure the routerFull power to configure the router In user mode, you enter the command In user mode, you enter the command

“enable” and then the privileged password“enable” and then the privileged password

Router> enableRouter> enablePassword:Password:RouterRouter## Means you’re in

privileged mode


Command ListsCommand Lists To get a list of commands available in either To get a list of commands available in either

user mode or privileged mode, enter a user mode or privileged mode, enter a ?? at the at the prompt.prompt.

Router> ?Router> ?Router# ?Router# ? Since the available commands will be more than Since the available commands will be more than

the screen can hold, you will get the the screen can hold, you will get the --More----More-- message at the bottom.message at the bottom.

Hitting the Hitting the space barspace bar will advance the screen to will advance the screen to show the next page.show the next page.


ipflash:interfacesipxversionparser

Router# show ?

Getting Help on a CommandGetting Help on a Command The ? can be used with a partial command to learn all the The ? can be used with a partial command to learn all the

available commands that match what you entered.available commands that match what you entered. To use this help feature, enter the partial command, then To use this help feature, enter the partial command, then

tap the tap the space barspace bar, then type , then type ?? For example...For example...

The Router returned all the available commands

for “show”


Error IndicatorError Indicator When you’ve entered an error in the When you’ve entered an error in the

command string, a carat (command string, a carat (^̂) symbol will ) symbol will indicate where the error occurred.indicate where the error occurred.

For example...For example...

Router# show runing-config ^% Invalid input detected at the ‘^’ marker


LabsLabs

Before taking the Ch. 2/3 test, make sure Before taking the Ch. 2/3 test, make sure you have done both of the required labs you have done both of the required labs for Ch. 3for Ch. 3 Lab 3.2.1Lab 3.2.1 Lab 3.2.2Lab 3.2.2

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Institute of Technology Sligo - Dept of Computing WANs and Router Basics Semester 2 Chapter 2: WANs & Routers Chapter 3: Router CLI Paul Flynn