Download - WANs and Router Basics Semester 2 Chapter 2: WANs & Routers Chapter 3: Router CLI By: Allan Johnson
WANs and Router Basics
Semester 2Chapter 2: WANs & Routers
Chapter 3: Router CLI
By: Allan Johnson
Table of ContentsTable of Contents
WAN Devices
WAN Standards
WAN Technologies
Router Basics
Router User Interface
WAN Devices
Table of Contents
WAN ServicesWAN Services
WANs provide for the exchange of data packets/frames between routers/bridges and the LANs they support.
A WAN interconnects LANs that are usually separated by large geographic areas.
WANs connect devices. Such devices include...
RoutersRoutersRouters offer many services including:
InternetworkingWAN serial interfaces
Routers can operate as...Internal RoutersBackbone Routers Area Border RoutersAutonomous System Boundary Routers
WAN Bandwidth SwitchesWAN Bandwidth Switches
Service provider equipment that connects to WAN bandwidth for voice, data and video communications.
ModemsModems
Also called CSU/DSUs (channel service units/digital service units)
Interface with voice-grade connection in order to convert analog signal to digital.
Represents the DCE side of the DTE/DCE connection.
More on DTE/DCE later
Communication ServersCommunication Servers
Concentrates dial-in and dial-out services.Equipment is usually at the service provider’s
site.
WAN Standards
Table of Contents
WAN StandardsWAN Standards
What layers of the OSI model do WAN standards describe?
Physical and Data Link Layers
WAN Physical LayerWAN Physical Layer
Protocols that describe how to provide electrical, mechanical, operational, and functional connections for WAN services.
These services are most often obtained from WAN service providers such as RBOCs, alternate carriers, post-telephone, and telegraph (PTT) agencies.
Describes the interface between the data terminal equipment (DTE) and the data circuit-terminating equipment (DCE).
WAN Physical LayerWAN Physical Layer
Typically, 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.
WAN Physical LayerWAN Physical Layer
Several physical layer standards specifying this interface between the DTE & DCE are...
EIA/TIA-232 EIA/TIA-449 V.24 V.35 X.21 G.703 EIA-530
WAN Data-Link LayerWAN Data-Link Layer
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.
WAN standards are defined and managed by a number of recognized authorities, including the following agencies: ITU-T, ISO, IETF, & EIA
WAN Data-Link EncapsulationsWAN Data-Link Encapsulations
High-Level Data Link Control (HDLC) Cisco default encapsulation; typically used between
routers running Cisco IOS; replacing SDLCStreamlined: no windowing or flow control may not be compatible with different vendors because
of the way each vendor has chosen to implement it. HDLC supports both point-to-point and multipoint
configurations with minimal overhead
WAN Data-Link EncapsulationsWAN Data-Link Encapsulations
Frame Relay uses high-quality digital facilities; uses simplified framing with no error correction
mechanisms (connectionless!!);it can send Layer 2 information much more rapidly
than other WAN protocols
WAN Data-Link EncapsulationsWAN Data-Link Encapsulations
PPP (Point-to-Point Protocol)Developed by IETF; replacing SLIPContains a field to identify the network layer protocolPPP can check for link quality during connection
establishmentSupports PAP (Password Authentication Protocol) &
CHAP (Challenge Handshake Authentication Protocol)
WAN Technologies
Table of Contents
WAN Technologies Overview
WAN Technologies Overview
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
WAN Technologies Overview
WAN Technologies Overview
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
Dedicated Digital ServicesDedicated Digital Services
T series in U.S. and E series in EuropeUses time division multiplexing to “slice up” data and
assign time slots for transmissionsT1 = 1.544 MbpsT3 = 44.736 MbpsE1 = 2.048 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); the x stands for a family of technologies
New WAN Technology for home use; decreasing bandwidth with increasing distance from the phone companies CO.
Data rates as high as 51.84 Mbps but more common to be in the 100s of Kbps
Varieties include HDSL, SDSL, ADSL, & VDSLModerate expense and getting cheaper
Dedicated Digital ServicesDedicated Digital Services
Synchronous Optical Network (SONET)Specialized high bandwidth technology for use at
various Optical Carrier speeds (OC) ranging from 51.84 Mbps (OC-1) to 9,952 Mbps (OC-192)
Uses lasers to divide the wavelength of the light into sections that can carry large amounts of data (Wave Division Multiplexing)
Very expensive; used by large ISPs and other Internet backbone entities.
WAN Technologies Overview
WAN Technologies Overview
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
Analog ServicesAnalog Services
Dial-up Modems (switched analog)Limited to 56 kbpsWorks with existing phone networkLow cost and widespread usage
Analog ServicesAnalog 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 users attach to a given network segment (behaving like an unswitched LAN)
Cost is relatively low; usage is small but increasing; the medium is coaxial cable.
Analog ServicesAnalog Services
TerrestrialBandwidths typically in the
11 Mbps range Cost is relatively lowLine-of-sight is usually
requiredUsage is moderate
SatelliteCan serve mobile users
and remote usersUsage is widespreadCost is very high
Wireless
WAN Technologies Overview
WAN Technologies Overview
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
Circuit Switched ServicesCircuit Switched Services
Plain Old Telephone System (POTS)Not a computer data service but...
POTS is an important component of our communication infrastructure and
It is still the standard for designing reliable networks
Circuit Switched ServicesCircuit Switched Services
Integrated Services Digital Network (ISDN)Historically important--first dial-up digital serviceCost is moderate; max. bandwidth = 128 kbps for
BRI (Basic Rate Interface)2 B channels @ 64kps and 1 D channel @ 16kpsB channels are voice/data channels; D for signaling
B
B
D
WAN Technologies Overview
WAN Technologies Overview
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
Packet Switched ServicesPacket Switched Services
X.25 (Connection-oriented)Older WAN technology developed in 1970sReliable--X.25 has been extensively debugged and
is now very stable--literally no errors in modern X.25 networks
Store & Forward--Since X.25 stores the whole frame to error check it before forwarding it on to the destination, it has an inherent delay (unlike Frame Relay) and requires large, expensive memory buffering capabilities.
Packet Switched ServicesPacket Switched Services
Frame Relay (Connectionless)More efficient and much faster than X.25Packet switched version of ISDN (which is circuit
switched); data rates up to 44.736Mbps with 56kbps and 384kbps being the most popular
Used mostly to forward LAN IP and IPX packets but can be used to forward other types of traffic
Primary competitive advantage is its low cost
WAN Technologies Overview
WAN Technologies Overview
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
Cell Switched ServicesCell Switched ServicesAsynchronous Transfer Mode (ATM)
Relatively new WAN Technology related to broadband ISDN; max. bandwidth = 622 Mbps
Developed in order to provide one technology for both WANs and LANs to transport data, video, and voice. (High Cost)
Key Benefits:One network for all traffic--voice, data, videoCompatible with current wiring infrastructure (cable plant)Very flexible and scalableSimplifies network management
Cell Switched ServicesCell Switched Services
Switched Multimegabit Data Service (SMDS)Closely related to ATM; SMDS is the MAN
(Metropolitan Area Network) implementation of ATMHigh 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 Basics
Table of Contents
Internal ComponentsInternal Components
RAM NVRAM Flash ROM
InterfacesConsoleAuxiliary
RAMRAM
Temporary storage for router configuration filesRAM content is lost on power down or restartStores...
Routing tablesARP cacheFast switching cachePacket bufferingAnd Packet hold queues
NVRAMNVRAM
Non-volatile RAMStores backup/startup configuration filesContent is not lost when router is powered down
or restarted.
FlashFlash
EEPROM (Electronically Erasable Programmable Read-Only Memory)
Holds the Cisco IOS (Internet Operating System)Allows updating of software without replacing the
Flash chipMultiple versions of IOS can be storedRetained on power down
ROMROM
Contains POST (Power On Self Test)A bootstrap program (loads the Cisco IOS)And operating system software
Backup, trimmed down version of the IOSUpgrades require installing new chip set
InterfacesInterfaces
Network connections through which packets enter and exit the router
Attached to the motherboard or as separate modules.
LabsLabs
Before moving on to Ch. 3, make sure you have done both of the required labs for Ch. 2
Lab 2.2.2Lab 2.2.3.2
Router User Interface
Table of Contents
User EXEC ModesUser EXEC Modes
User modeLimited mode used for checking the routers status,
looking at routing tables, 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 the name of the router.
Password:Router>
Means you’re in user mode
Privileged EXEC ModesPrivileged EXEC Modes
Privileged modeDoes everything User mode doesFull power to configure the routerIn user mode, you enter the command “enable” and
then the privileged password
Router> enablePassword:Router#
Means you’re in privileged mode
Command ListsCommand Lists
To get a list of commands available in either user mode or privileged mode, enter a ? at the prompt.
Router> ?Router# ?Since the available commands will be more than
the screen can hold, you will get the --More-- message at the bottom.
Hitting the space bar will advance the screen to show the next page.
ipflash:interfacesipxversionparser
Router# show ?
Getting Help on a Command
Getting Help on a Command
The ? can be used with a partial command to learn all the available commands that match what you entered.
To use this help feature, enter the partial command, then tap the space bar, then type ?
For example...
The Router returned all the available commands
for “show”
Error IndicatorError Indicator
When you’ve entered an error in the command string, a carat (^) symbol will indicate where the error occurred.
For example...
Router# show runing-config ^% Invalid input detected at the ‘^’ marker
LabsLabs
Before taking the Ch. 2/3 test, make sure you have done both of the required labs for Ch. 3
Lab 3.2.1Lab 3.2.2
End Slide Show
Table of Contents