Transcript Table of Contents

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
Table of Contents

WAN Devices

WAN Standards

WAN Technologies

Router Basics

Router User
Interface
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WAN Devices
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WAN Services
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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...
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Routers
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Routers offer many services including:
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Internetworking
WAN serial interfaces
Routers can operate as...
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Internal Routers
Backbone Routers
Area Border Routers
Autonomous System Boundary Routers
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WAN Bandwidth Switches
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Service provider equipment that connects
to WAN bandwidth for voice, data and
video communications.
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Modems
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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
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Communication Servers
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Concentrates dial-in and dial-out services.
Equipment is usually at the service
provider’s site.
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WAN Standards
Institute of Technology Sligo - Dept of Computing
WAN Standards
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What layers of the OSI model do WAN
standards describe?
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Physical and Data Link Layers
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WAN Physical Layer
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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 circuitterminating equipment (DCE).
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WAN Physical Layer
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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.
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WAN Physical Layer
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Several physical layer standards specifying this
interface between the DTE & DCE are...
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EIA/TIA-232
EIA/TIA-449
V.24
V.35
X.21
G.703
EIA-530
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WAN Data-Link Layer
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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 multiaccess switched services.
WAN standards are defined and managed by a
number of recognized authorities, including the
following agencies: ITU-T, ISO, IETF, & EIA
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WAN Data-Link Encapsulations
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High-Level Data Link Control (HDLC)
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Cisco default encapsulation; typically used
between routers running Cisco IOS;
replacing SDLC
Streamlined: 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
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WAN Data-Link Encapsulations
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Frame Relay
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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
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WAN Data-Link Encapsulations
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PPP (Point-to-Point Protocol)
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Developed by IETF; replacing SLIP
Contains a field to identify the network layer
protocol
PPP can check for link quality during
connection establishment
Supports PAP (Password Authentication
Protocol) & CHAP (Challenge Handshake
Authentication Protocol)
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WAN Technologies
Institute of Technology Sligo - Dept of Computing
WAN Technologies
Overview
Dedicated
• T1, E1, T3, E3
• xDSL
• SONET
Circuit
Switched
• POTS
• ISDN
Switched
Packet
Switched
• X.25
• Frame
Relay
Analog
• Dial-up modems
• Cable modems
• Wireless
Cell
Switched
• ATM
• SMDS
Institute of Technology Sligo - Dept of Computing
WAN Technologies
Overview
Dedicated
• T1, E1, T3, E3
• xDSL
• SONET
Circuit
Switched
• POTS
• ISDN
Switched
Packet
Switched
• X.25
• Frame
Relay
Analog
• Dial-up modems
• Cable modems
• Wireless
Cell
Switched
• ATM
• SMDS
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Dedicated Digital Services
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Dedicated Digital Services provide full-time
connectivity through a point-to-point link
T series in U.S. and E series in Europe
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Uses time division multiplexing to “slice up”
data and assign time slots for transmissions
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T1 = 1.544 Mbps
T3 = 44.736 Mbps
E1 = 2.048 Mbps
E3 = 34.368 Mbps
•Uses twisted pair & fiber
•Extremely popular
•Moderate cost
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Dedicated Digital Services
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Digital Subscriber Lines (xDSL); the x stands
for a family of technologies
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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, & VDSL
Moderate expense and getting cheaper
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Dedicated Digital Services
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Synchronous Optical Network (SONET)
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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.
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WAN Technologies
Overview
Dedicated
• T1, E1, T3, E3
• xDSL
• SONET
Circuit
Switched
• POTS
• ISDN
Switched
Packet
Switched
• X.25
• Frame
Relay
Analog
• Dial-up modems
• Cable modems
• Wireless
Cell
Switched
• ATM
• SMDS
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Analog Services
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Dial-up Modems (switched analog)
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Limited to 56 kbps
Works with existing phone network
Low cost and widespread usage
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Analog Services
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Cable Modems (Shared Analog)
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Puts data signals on the same cable as television
signals
Increasing 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.
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Analog Services
Wireless
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Terrestrial
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Bandwidths typically in
the 11 Mbps range
Cost is relatively low
Line-of-sight is usually
required
Usage is moderate
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Satellite
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Can serve mobile
users and remote
users
Usage is widespread
Cost is very high
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WAN Technologies
Overview
Dedicated
• T1, E1, T3, E3
• xDSL
• SONET
Circuit
Switched
• POTS
• ISDN
Switched
Packet
Switched
• X.25
• Frame
Relay
Analog
• Dial-up modems
• Cable modems
• Wireless
Cell
Switched
• ATM
• SMDS
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Circuit Switched Services
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Plain Old Telephone System (POTS)
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Not a computer data service but...
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POTS is an important component of our
communication infrastructure and
It is still the standard for designing reliable
networks
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Circuit Switched Services
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Integrated Services Digital Network
(ISDN)
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Historically important--first dial-up digital
service
Cost is moderate; max. bandwidth = 128 kbps
for BRI (Basic Rate Interface)
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2 B channels @ 64kps and 1 D channel @ 16kps
B channels are voice/data channels; D for
B
signaling
D
B
Institute of Technology Sligo - Dept of Computing
WAN Technologies
Overview
Dedicated
• T1, E1, T3, E3
• xDSL
• SONET
Circuit
Switched
• POTS
• ISDN
Switched
Packet
Switched
• X.25
• Frame
Relay
Analog
• Dial-up modems
• Cable modems
• Wireless
Cell
Switched
• ATM
• SMDS
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Packet Switched Services
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X.25 (Connection-oriented)
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Older WAN technology developed in 1970s
Reliable--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.
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Packet Switched Services
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Frame Relay (Connectionless)
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More efficient and much faster than X.25
Packet 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
Institute of Technology Sligo - Dept of Computing
WAN Technologies
Overview
Dedicated
• T1, E1, T3, E3
• xDSL
• SONET
Circuit
Switched
• POTS
• ISDN
Switched
Packet
Switched
• X.25
• Frame
Relay
Analog
• Dial-up modems
• Cable modems
• Wireless
Cell
Switched
• ATM
• SMDS
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Cell Switched Services
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Asynchronous Transfer Mode (ATM)
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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:
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One network for all traffic--voice, data, video
Compatible with current wiring infrastructure (cable plant)
Very flexible and scalable
Simplifies network management
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Cell Switched Services
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Switched Multimegabit Data Service
(SMDS)
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Closely related to ATM; SMDS is the MAN
(Metropolitan Area Network) implementation
of ATM
High Cost with max. bandwidth 44.736 Mbps
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WAN Technologies Review
Acronym
Name
Dedicated Digital Services
T1, T3
T1, T3
xDSL
Digital Subscriber Line
Synchronous Optical
SONET
Network
Analog Services
Dial-up Modem
Modem
Max. Bandwidth
Comments
1.544 & 44.736 Mbps Widely used telecommunications
384 kbps
New technology over phone lines
9,992 Mbps
Very fast optical fiber transmission
56 kbps
Mature technology over phone lines
10 Mbps
New technology using cable TV
Terrestrial Wireless Wireless
11 Mbps
Microwave and laser links
Satellite Wireless
Wireless
Circuit Switched Services
Plain Old Telephone
POTS
Service
Integrated Services
ISDN
Digital Network
Packet Switched Services
X.25
X.25
Frame Relay
Frame Relay
Cell Switched Services
Asynchronous
ATM
Transfer Mode
Switched Multimegabit
SMDS
Data Service
2 Mbps
Microwave and laser links
4 kHz Analog
The Standard for Reliability
128 kbps
Data and Voice Together
up to 44.736 Mbps
An Old Reliable, Workhorse
A flexible new workhorse; son of ISDN
622 Mbps
High powered Networks
Cable Modem
Cable Modem
1.544 & 44.736 Mbps MAN variant of ATM
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Router Basics
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Internal Components
RAM
Console
Auxiliary
NVRAM Flash
Interfaces
ROM
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RAM
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Temporary storage for router configuration files
RAM content is lost on power down or restart
Stores...
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Routing tables
ARP cache
Fast switching cache
Packet buffering
And Packet hold queues
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NVRAM
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Non-volatile RAM
Stores backup/startup configuration files
Content is not lost when router is powered
down or restarted.
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Flash
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EEPROM (Electronically Erasable
Programmable Read-Only Memory)
Holds the Cisco IOS (Internet Operating
System)
Allows updating of software without
replacing the Flash chip
Multiple versions of IOS can be stored
Retained on power down
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ROM
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Contains POST (Power On Self Test)
A bootstrap program (loads the Cisco IOS)
And operating system software
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Backup, trimmed down version of the IOS
Upgrades require installing new chip set
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Interfaces
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Network connections through which
packets enter and exit the router
Attached to the motherboard or as
separate modules.
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Labs

Before moving on to Ch. 3, make sure you
have done both of the required labs for
Ch. 2


Lab 2.2.2
Lab 2.2.3.2
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Router User Interface
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User EXEC Modes
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User mode
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Limited mode used for checking the routers status,
looking at routing tables, etc.
You cannot configure the router
Once 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
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Privileged EXEC Modes
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Privileged mode
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Does everything User mode does
Full power to configure the router
In user mode, you enter the command
“enable” and then the privileged password
Router> enable
Password:
Router#
Means you’re in
privileged mode
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Command Lists
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To get a list of commands available in either
user mode or privileged mode, enter a ? at the
prompt.
Router> ?
Router# ?
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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.
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Getting Help on a Command
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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...
Router# show ?
ip
flash:
interfaces
ipx
version
parser
The Router returned all
the available commands
for “show”
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Error Indicator
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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
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Labs

Before taking the Ch. 2/3 test, make sure
you have done both of the required labs
for Ch. 3


Lab 3.2.1
Lab 3.2.2