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Chabot College

Chabot College. ELEC 99.08 Wide Area Network Introduction. WANs. WAN Technologies. Application Layer. Presentation Layer. Session Layer. Transport Layer. Network Layer. Data Link Layer. WAN technologies. Physical Layer. Physical and Data Link. Layer 2. Layer 1. WAN: Layer 1.

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Chabot College

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  1. Chabot College ELEC 99.08 Wide Area Network Introduction

  2. WANs

  3. WAN Technologies Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer WAN technologies Physical Layer

  4. Physical and Data Link Layer 2 Layer 1

  5. WAN: Layer 1 WAN physical layer protocols describe how to provide connections.

  6. The WAN interface Your Ethernet LAN connects to your router. But what does you router connect to? ? WAN 802.3 LAN Cat5 UTP

  7. PACBELL Regional Bells Provide Media Regional Bells usually provide the media for Wide-Area Network connectivity. SF NY

  8. WAN Pipes More….

  9. The WAN interface How do routers connect to the phone companies lines? to phone company

  10. Data 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

  11. Data Terminal Equipment Your home computer can also be a DTE. How do you connect to the phone company’s network at home?

  12. DTEs and DCEs At home, you connect to the phone company’s network using a modem. modem to phone company

  13. Data 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).

  14. Data 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.

  15. DTEs and DCEs A DTE interfaces with a DCE to gain access to the phone company’s network. Phone Company’s Network Customer’s Network DTE DCE Modem PC Router CSU/DSU

  16. DTEs and DCEs • Router to CSU/DSU connection: • Serial port on router • V.35 port on CSU/DSU • V.35 Cable between CSU/DSU DTE DCE

  17. DTEs and DCEs Typical WAN configuration: Oakland Hayward CSU/DSU CSU/DSU phone company digital line DTE DCE DCE DTE

  18. DTEs and DCEs Our 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. Oakland Hayward Serial interface Serial interface V.35 Cables Back-to-Back DTE DCE

  19. WAN: 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)

  20. WAN at Layer 2 dedicated switched

  21. Data Link Layer: WAN Protocols

  22. HDLC 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

  23. PPP 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

  24. Frame 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

  25. ISDN 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

  26. WAN Technology Options

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