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1、Wide Area Networking Wide Area Networking ProtocolsProtocolsOverviewOverview1.0 Wide Area Networks2.0 High-Level Data-Link Control Protocol HDLC3.0 Point-to-Point Protocol PPP4.0 Frame Relay5.0 Integrated Services Digital Network6.0 Dial-on Demand Routing DDR1.01.0Wide Area NetworksWide Area Network
2、s1.1 Introduction to Wide Area Services1.2 Defining WAN Terms1.2 WAN Connection Types1.3 WAN Protocols1.11.1Introduction to Wide Area ServicesIntroduction to Wide Area ServicesnTo extend LANs to other LANs at remote sitesnConnecting sites together so information can be exchangednService providers le
3、ase or share their already installed connections1.21.2Defining WAN Terms Defining WAN Terms WAN Service ProvidersWAN Service ProvidersnCustomer Premises Equipment CPElEquipment that is owned and located at the subscribers premisesnDemarcation demarclThe place where the CPE ends and the local loop po
4、rtion of the service begins usually in the“phone-closetnLocal LooplConnects the demarc to the closest switching office COnCentral Office CO/Point of Presence POPlConnects the customers to the providers switching network.nToll NetworklThe switches and facilities,trunks,inside the WAN providers“cloud.
5、Synchronous serialAsynchronous serial,ISDNSynchronous serial1.31.3WAN Connection TypesWAN Connection TypesDedicated Leased lines Point to Point ConnectionA pre-established WAN munications path from the CPE,through the DCE switch,to the CPE of the remote site,allowing DTE networks to municate at any
6、time with no setup procedures before transmitting data.Circuit SwitchingSets 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 SwitchingShare bandwidth with other panies to sav
7、e money.For not constantly data transmission otherwise using leased lineTelephone panyServiceProviderSpeed up to 45 MbpsLow-bandwidth data transfersSpeed range from 56K to 2.048M1.41.4WAN ProtocolsWAN ProtocolsFrame RelaylPacket-switched technology with Data Link and Physical Layer specificationlPro
8、vide Dynamic-bandwidth allocation and congestion controlISDN Integrated Services Digital NetworklVoice and Data transmission over existing phone lineslHigher speed than analog dial-up link;good choice as a backup linkLAPB Link Access Procedure,BalancedlA connection-oriented protocol at the Data Link
9、 layer for use with X.25lVery high overhead;only used if link is very error proneHDLC High-Level Data Link ControllDerived 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 equipmentPPP
10、 Point-to-Point ProtocollAn industry-standard protocol,to create point-to-point links between different vendors equipmentlAllow authentication and multi-link connections,run over asyn.&syn.links2.02.0High-Level Data-Link Control Protocol High-Level Data-Link Control Protocol HDLCHDLCnISO standard,bi
11、t-oriented Data Link layer protocolnA point-to-point protocol used on leased linesnDefault encapsulation used by Cisco routers over synchronous serial links;or type the following mandslRouterconfig-if#Encapsulation hdlcnEach vendor has a different way for the HDLC protocol to municate with the Netwo
12、rk layer protocolnNo authenticationSynchronous Physical MediaHDLCIPIPXAppleTalkBit-oriented protocols use single bit as control information byte-oriented use entire byte3.03.0Point-to-Point ProtocolPoint-to-Point Protocol3.1 Introduction to PPP3.2 Point-to-point Protocol Stack3.3 Link Control Protoc
13、ol LCP Configuration Options3.4 PPP Session Establishment3.5 PPP Authentication Methods3.6 Configuring PPP on Cisco Routers3.7 Verifying PPP Encapsulation3.13.1Introduction to PPPIntroduction to PPPnA Data-link,point-to-point protocol used lOver asynchronous serial dial uplOver synchronous serial IS
14、DN,Leased linelLCP Link Control Protocol to build and maintain data-link connectionsnUse to transport layer-3 packets across a Data-link layern ponents:lEIT/TIA-232-C formerly RS-232 physical layer international standard for serial municationlHDLC A method for encapsulating datagrams over serial lin
15、kslLCP A method of establishing,configuring,maintaining,and terminating the point-to-point connectionlNCP Encapsulating different Network layer protocol across a PPP data link3.23.2Point-to-point Protocol StackPoint-to-point Protocol StackNetwork LayerIPIPXOthers,e.g.AppleTalkIPCPIPXCPOthersData Lin
16、k LayerNetwork Control Protocol NCPLink Control Protocol LCPAuthentication,other optionsHigh-Level Data Link Control Protocol HDLCPhysical LayerSynchronous or Asynchronous Physical Mediasuch as EIA/TIA-232,V.24,V.35,ISDNPPPServiceProviderTCP/IPAppleTalkPPP EncapsulationTCP/IPIPXAppleTalkIPX3.33.3Lin
17、k Control Protocol Link Control Protocol LCPLCP Configuration Configuration OptionsOptionsLCP offers PPP the following options:nAuthenticationlPAP&CHAPn pressionlto increase the throughput of PPP connection Stacker&PredictornError DetectionlQuality&Magic NumbernMulti-linklstarting in IOS 11.1lSplits
18、 the load for PPP over two or more parallel circuits bundle3.43.4PPP Session EstablishmentPPP Session EstablishmentThree phases of session establishmentnLink-establishment phaselLCP packets are sent by each PP device to configure and test the linknAuthentication phase optionallCHAP or PAP is used to
19、 authenticate a linknNetwork-layer protocol phaselNCP to encapsulate multiple Network-layer protocols and then send over a PPP data link3.53.5PPP Authentication MethodsPPP Authentication MethodsPassword Authentication Protocol PAPnLess securenPasswords are sent in clear textnOnly perform upon the in
20、itial link establishmentnWhen the PPP link is first established,the remote node sent back the username and password for authentication at the sending routerChallenge Authentication Protocol CHAPnUsed at the initial startup of a link and at periodic checkupa challenge requestA value calculatedwith MD
21、5Check the value,if not match-terminate at once!*MD5 is a one-way hash function3.63.6Configuring PPP on Cisco RoutersConfiguring PPP on Cisco RoutersnRouterconfig-if#lEncapsulation ppplConfiguring PPP encapsulation on an interface serialnRouterconfig#lHostname lUsername password lCase-sensitive and
22、Plain-text passwordlThe password on both routers must be the samelBoth the local and remote router must be configurednRouterconfig-if#lppp authenticaiton chap|pap lConfiguring the authentication type on an interface seriallIf both are chosen,the first one will be used.If the first one failed,the sec
23、ond one will be used.3.73.7Verifying PPP EncapsulationVerifying PPP EncapsulationnRouter#lShow int s0lShow the encapsulation method,protocol support,etc.nRouter#lDebug ppp authenticationlVerify the PPP authentication configuration4.04.0Frame RelayFrame Relay4.1 Introduction to Frame Relay4.2 Frame R
24、elay Terminology4.3 Data Link Connection Identifiers DLCIs4.4 Local Management Interface LMI4.5 Sub-interface4.6 Mapping Frame Relay4.7 Frame Relay Configuration Tasks4.8 Frame Relay Congestion Control4.9 mitted Information Rate CIR4.10 Monitoring Frame Relay4.14.1Introduction to Frame RelayIntroduc
25、tion to Frame RelaynFrame Relay works on physical and data link layer.nFrame Relay provides connection-oriented,Data Link layer munication via virtual circuits just as X.25 does.These virtual circuits are logical connections created between two DTEs across a packet-switched network,which is identifi
26、ed by a DLCI,or Data Link Connection Identifier.nFrame Relay is more efficient and faster than X.25 because it assumes error checking will be done through higher-layer protocols and application services.nAlso,like X.25,Frame Relay uses both PVCs Permanent Virtual Circuits and SVCs Switched Virtual C
27、ircuits,although most Frame Relay networks use only PVCs.This virtual circuit provides the plete path to the destination network prior to the sending of the first frame.nFrame Relay is used over a variety of network protocols.nFrame Relay interface between the user and the network equipment will tra
28、nsmit and receive frames using first-in first-out queuing on a statistically multiplexed circuit4.24.2Frame Relay TerminologyFrame Relay TerminologyHub/SwitchDSU/CSURouterDLCI 16 DSU/CSUUserDemarcCentral OfficeDemarcDSU/CSUHub/SwitchRouterDLCI 17 DSU/CSUUserFrame actually transverse thisPVCRouter se
29、e thisUser onlysee thisFrame Relay network allow users to municate between two DTE devices through DCE devices.123456Remember that before data is sent through the cloud,the virtual circuit is created from end to end.Central OfficeWAN784.34.3Data Link Connection Identifier Data Link Connection Identi
30、fier DLCIDLCI AssignmentAssignmentnFrame Relay virtual circuits PVCs are identified by DLCIs.nFrame Relay provider sets up the DLCI numbers to be used by the routers for establishing PVCsnFor the IP devices at each end of a virtual circuit to municate,their IP addresses need to be mapped to DLCIs.Th
31、is mapping can function as a multipoint deviceone that can identify to the Frame Relay network the appropriate destination virtual circuit for each packet that is sent over the single physical interface.The mappings can be done dynamically through IARP or manually through the Frame Relay map mand.nE
32、ach DLCI is locally significant.That means DLCI numbers do not necessarily need to be unique.Two DLCI numbers can be the same on different sides of a link because Frame Relay maps a local DLCI number to a virtual circuit on each interface of the switch.Each remote office can have its own DLCI number
33、 and municate with the corporate office using unique DLCI numbers.nDLCI start at 16.DLCI 1023 is specific for LMI use,DLCIs 1019 to 1022 address multicastnMap entry indicates static route to destination4.44.4Local Management Interface Local Management Interface LMILMInThe LMI is a signaling standard
34、 between a CPE device router and a frame switch.The LMI is responsible for managing and maintaining status between these devices.LMI messages provide information about the following:lKeepalives Verify data is flowinglMulticasting Provides a local DLCI PVClMulticast addressing Provides global signifi
35、cancelStatus of virtual circuits Provides DLCI statusnThere are three standard LMI signaling formats are supported:lCisco LMI defined by the Gang of Four defaultlANSI Annex D defined by ANSI standard T1.617lITU-T q933a Annex A defined by Q.933nRouters receive LMI information on a frame-encapsulated
36、interface and update the virtual circuit status to one of three different states:lActive state Everything is up and routers can exchange information.lInactive state The routers interface is up and working with a connection to the switching office,but the remote router is not working.lDeleted state T
37、his means that no LMI information is being received on the interface from the switch.It could be a mapping problem or a line failure.4.54.5SubinterfacesSubinterfacesnCreating Subinterfaces in order to have multiple virtual circuits on a single serial interface and yet treat each as a separate interf
38、ace with different configuration.lDefines logical sub-interfaces on the serial linelEach sub-interface uses a DLCI to represents the destinations for Frame Relay PVC networklEach sub-interface uses its own sub-networklWork for Partial mesh Frame Relay networknConfiguring subinterfaces actually works
39、 to subdivide the Frame Relay network into smaller subnetworks.nSubinterfaces also solve the problem with routing protocols that use split horizon.nThere are two types of subinterfaces:lPoint-to-point Used when a single virtual circuit connects one router to another.Each point-to-point subinterface
40、requires its own subnet.lMultipoint Used when the router is the center of a star of virtual circuits.Uses a single subnet for all routers serial interfaces connected to the frame switch.4.64.6Mapping Frame RelayMapping Frame RelaynIn order for IP devices at the ends of virtual circuits to municate,t
41、heir addresses must be mapped to the DLCIs.nThere are two ways to make this mapping happen:lUse the Frame Relay map mand for manually mapping.This is also the only way to configure multiple frame encapsulation types on an interfacelUse the inverse-arp by default enable function to perform dynamic ma
42、pping of the IP address to the DLCI number but its not as stable as using the map mand-because virtual circuits can be insidiously and dynamically mapped to unknown devices.4.74.7Frame Relay Configuration Tasks Frame Relay Configuration Tasks 1 1nRouterconfig-if#lencapsulation frame-relay cisco|ietf
43、lSets frame relay encapsulation for connection to non-Cisco Routers the default encapsulation is for same Cisco RoutersnRouterconfig-if#lframe-relay lmi-type ansi|cisco|q933alSelects LMI typelBeginning with IOS version 11.2,the LMI type is auto-sensed.This enables the interface to determine the LMI
44、type supported by the switch.nRouterconfig-if#lframe-relay map protocol-address cisco|ietf broadcast lDefines how to reach a destinationlThe broadcast keyword at the end tells the router to forward broadcasts for this interface to this specific virtual circuit.Remember that Frame Relay is a nonbroad
45、cast multiaccess NBMA encapsulation method,which will not broadcast routing protocols by default.4.74.7Frame Relay Configuration Tasks Frame Relay Configuration Tasks 2 2nRouterconfig#linterface.sub-interface-number point-to-point|multipointlCreates the logical sub-interface for Frame RelaylGenerall
46、y the subinterface number matches the DLCI number but this is not a requirement it only helps in the administration of the interfaces.nRouterconfig-if#lframe-relay interface-dlci lAssigns a DLCI to the Frame Relay sub-interface on the router4.84.8Frame Relay Congestion ControlFrame Relay Congestion
47、ControlFrame Relay switch control congestion as follows:nDE Discard Eligibility When a Frame Relay router detects congestion on the Frame Relay network,it will turn the DE bit on in a Frame Relay packet header.If the switch is congested,the Frame Relay switch will discard the packets with the DE bit
48、 set first.If your bandwidth is configured with a CIR of zero,the DE will always be on.nFECN Forward-Explicit Congestion Notification When the Frame Relay network recognizes congestion in the cloud,the switch will set the FECN bit to 1 in a Frame Relay packet header.This will indicate to the destina
49、tion DCE that the path just traversed is congested.nBECN Backward-Explicit Congestion Notification When the switch detects congestion in the Frame Relay network,it will set the BECN bit in a Frame Relay packet and send it to the source router,telling it to slow down the rate at which it is transmitt
50、ing packets.4.94.9 mitted Information Control mitted Information Control CIRCIRnFrame Relay is based on the assumption that not all customers need to transmit constant data all at the same time.Frame Relay works best with bursty traffic.nFrame Relay providers allow customers to buy a lower amount of