Wide Area Networking Protocols天马行空官方博客：http:/t.qq.com/tmxk_docin ；QQ:1318241189；QQ群：175569632Overview1.0Wide Area Networks2.0High-Level Data-Link Control Protocol (HDLC)3.0Point-to-Point Protocol (PPP)4.0Frame Relay5.0Integrated Services Digital Network6.0Dial-on Demand Routing (DDR)天马行空官方博客：http:/t.qq.com/tmxk_docin ；QQ:1318241189；QQ群：1755696321.0Wide Area Networks1.1Introduction to Wide Area Services1.2Defining WAN Terms1.2WAN Connection Types1.3WAN Protocols1.1Introduction to Wide Area ServicesnTo extend LANs to other LANs at remote sitesnConnecting sites together so information can be exchangednService providers lease or share their already installed connections1.2Defining WAN Terms (WAN Service Providers)nCustomer Premises Equipment (CPE)lEquipment that is owned and located at the subscribers premisesnDemarcation (demarc)lThe place where the CPE ends and the local loop portion of the service begins (usually in the “phone-closet”)nLocal LooplConnects the demarc to the closest switching office (CO)nCentral Office (CO) / Point of Presence (POP)lConnects the customers to the providers switching network.nToll NetworklThe switches and facilities, (trunks), inside the WAN providers “cloud”. Synchronous serialAsynchronous serial, ISDNSynchronous serial1.3WAN Connection TypesDedicated Leased lines (Point to Point Connection) A pre-established WAN communications path from the CPE, through the DCE switch, to the CPE of the remote site, allowing DTE networks to communicate at any time with no setup procedures before transmitting data.Circuit Switching Sets up line like a phone call. No data can transfer before the end-to-end connection is established. Use dial-up modems and ISDN. It is used for low-bandwidth data transfers.Packet Switching Share bandwidth with other companies to save money. For not constantly data transmission (otherwise using leased line)Telephone CompanyService ProviderSpeed up to 45 MbpsLow-bandwidth data transfersSpeed range from 56K to 2.048M1.4WAN ProtocolsFrame RelaylPacket-switched technology with Data Link and Physical Layer specificationlProvide Dynamic-bandwidth allocation and congestion control ISDN (Integrated Services Digital Network)lVoice and Data transmission over existing phone lineslHigher speed than analog dial-up link; good choice as a backup link LAPB (Link Access Procedure, Balanced)lA connection-oriented protocol at the Data Link layer for use with X.25lVery high overhead; only used if link is very error prone HDLC (High-Level Data Link Control)lDerived from Synchronous Data Link Control (SDLC) created by IBMlA connection-oriented protocol at the Data Link Layer, low overheadlEach vendors HDLC is proprietary for their equipment PPP (Point-to-Point Protocol)lAn industry-standard protocol, to create point-to-point links between different vendors equipmentlAllow authentication and multi-link connections, run over asyn. or type the following commandslRouter(config-if)# Encapsulation hdlcnEach vendor has a different way for the HDLC protocol to communicate with the Network layer protocolnNo authenticationSynchronous Physical MediaHDLCIPIPXAppleTalkBit-oriented protocols use single bit as control information (byte-oriented use entire byte)3.0Point-to-Point Protocol3.1Introduction to PPP3.2Point-to-point Protocol Stack3.3Link Control Protocol (LCP) Configuration Options3.4PPP Session Establishment3.5PPP Authentication Methods3.6Configuring PPP on Cisco Routers3.7Verifying PPP Encapsulation3.1Introduction to PPPnA Data-link, point-to-point protocol used lOver asynchronous serial (dial up)lOver synchronous serial (ISDN, Leased line)lLCP (Link Control Protocol) to build and maintain data-link connectionsnUse to transport layer-3 packets across a Data-link layernComponents:lEIT / TIA-232-C (formerly RS-232) physical layer international standard for serial communicationlHDLC A method for encapsulating datagrams over serial linkslLCP A method of establishing, configuring, maintaining, and terminating the point-to-point connectionlNCP Encapsulating different Network layer protocol across a PPP data link3.2Point-to-point Protocol StackNetwor k LayerIPIPXOthers, e.g. AppleTal k IPCPIPXCPOthers Data Link LayerNetwork Control Protocol (NCP) Link Control Protocol (LCP) Authentication, other options High-Level Data Link Control Protocol (HDLC) Physical LayerSynchronous or Asynchronous Physical Media (such as EIA/TIA-232, V.24, V.35, ISDN)PPPService ProviderTCP/IPAppleTalkPPP EncapsulationTCP/IPIPXAppleTalkIPX3.3Link Control Protocol (LCP) Configuration OptionsLCP offers PPP the following options:nAuthenticationlPAP protocols span across OSIs Physical, Data Link and Network layersAlso used for other functions (e.g. alarm system for a building) which doesnt need much bandwidth5.3 Basic Rate Interface (BRI) - 2nSetup procedure for a BRI call:lD channel between router and ISDN switch comes uplISDN switch uses the SS7 signaling technique to setup a pa