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CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Chabot CollegeChabot College
ELEC 99.08ELEC 99.08Wide Area Network Introduction
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
WANsWANs
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
WAN TechnologiesWAN Technologies
Data Link Layer
Physical Layer
Network Layer
Session Layer
Transport Layer
Presentation Layer
Application Layer
WAN technologies
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Physical and Data LinkPhysical and Data Link
Layer 2
Layer 1
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
WAN: Layer 1WAN: Layer 1
WAN physical layer protocols describe how to provide connections.
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
The WAN interfaceThe WAN interface
Your Ethernet LAN connects to your router. But what does you router connect to?
802.3 LAN ? WAN
Cat5 UTP
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Regional Bells Provide MediaRegional Bells Provide Media
PACBELL
Regional Bells usually provide the media for Wide-Area Network connectivity.
SF NY
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
WAN PipesWAN Pipes
More….
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
The WAN interfaceThe WAN interface
How do routers connect to the phone companies lines?
to phone company
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Data Terminal EquipmentData Terminal Equipment
Routers are usually considered DTEs. DTEs are devices at the end of a user’s network that serve as a data source, destination, or both.
The router is a DTE, or Data Terminal Equipment
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Data Terminal EquipmentData Terminal Equipment
Your home computer can also be a DTE.
How do you connect to the phone company’s network at home?
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
to phone company
modem
DTEs and DCEsDTEs and DCEs
At home, you connect to the phone company’s network using a modem.
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Data Circuit EquipmentData Circuit Equipment
A modem is a type of DCE, or Data Circuit-Termination Equipment. It’s the device at the end of the service provider’s network (phone company).
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Data Circuit EquipmentData Circuit Equipment
• Another type of DCE is a CSU/DSU– Channel Service Unit– Data Service Unit
• CSU/DSU is located at the end of the service provider’s network (phone company).
• connects to router Serial port.
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Customer’s Network
Phone Company’s
Network
DTEs and DCEsDTEs and DCEs
A DTE interfaces with a DCE to gain access to the phone company’s network.
DTE DCE
PCPCRouterRouter
ModemModemCSU/DSUCSU/DSU
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
DTEs and DCEsDTEs and DCEs• Router to CSU/DSU connection:
– Serial port on router– V.35 port on CSU/DSU – V.35 Cable between
CSU/DSU
DCEDTE
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
phone company
digital line
CSU/DSU
DTEs and DCEsDTEs and DCEsTypical WAN configuration:
CSU/DSU
DCE DCE
HaywardOakland
DTE DTE
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
DTEs and DCEsDTEs and DCEsOur Lab’s unusual configuration:
No digital phone lines, no CSU/DSUs.
The WAN is simulated in our lab.
Therefore, one router must play the DCE role - very unusual.
Serial interface Serial interface
V.35 CablesBack-to-Back
HaywardOakland
DTE DCE
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
WAN: Layer 2WAN: Layer 2
WAN data-link protocols describe how frames are carried between systems on a single data path.
– point-to-point
– multipoint
– multiaccess (Frame Relay)
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
WAN at Layer 2WAN at Layer 2
dedicated
switched
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Data Link Layer: WAN ProtocolsData Link Layer: WAN Protocols
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
HDLCHDLC
High-level Data Link Control– usually used when connecting one router directly
to another (point-to-point)
– also is capable of supporting multipoint connections (multiple point-to-point) (test question)
– requires dedicated private digital lines
– HDLC implementations are proprietary
– Cisco serial interfaces default to HDLC
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
PPPPPP
Point-to-Point Protocol– used in point-to-point dedicated connections
– used by
• routers over dedicated digital lines
• POTS users over dial-up (circuit switched) lines (Windows & Mac dial-up networking)
– descendant of SLIP
– open standard (RFC 1661)
– allows authentication (PAP, CHAP)
– allows multiple layer 3 protocols
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
Frame RelayFrame Relay
Frame Relay– packet switched
– private dedicated digital lines not required
– one physical link can handle multiple logical links - (multiaccess)
– descendant of X.25
– simplified frame (no error correction) relies on today’s superior data links
– very fast
– cheap: pay for what you use
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
ISDNISDN
Integrated Services Digital Network– circuit switched - (over digital voice/data line)
– designed to transmit voice, data, video over existing phone lines
– used primarily for remote access via modems
– not very fast (especially BRI - 128 Kbps)
– may disappear with the emergence of cable modems and DSL
CISCO NETWORKING ACADEMYCISCO NETWORKING ACADEMY
WAN Technology Options WAN Technology Options