【正文】 ter1usernamerouter2passwordxxxinterfaceSerial0ipaddressclockrate1000000pppauthenticationchap!Router2:hostnamerouter2usernamerouter1passwordxxxinterfaceSerial0ipaddresspppauthenticationchap!ISDN（ISDN）綜合數(shù)字業(yè)務(wù)網(wǎng)（ISDN）由數(shù)字電話和數(shù)據(jù)傳輸服務(wù)兩部分組成，一般由電話局提供這種服務(wù)。ISDN的基本速率接口（BRI）服務(wù)提供2個(gè)B信道和1個(gè)D信道（2B+D）。BRI的B信道速率為64Kbps,用于傳輸用戶數(shù)據(jù)。D信道的速率為16Kbps，主要傳輸控制信號。在北美和日本，ISDN的主速率接口（PRI）提供23個(gè)B信道和1個(gè)D信道，其中D信道速率為64Kbps。而在歐洲、澳大利亞等國家，ISDN的PRI提供30個(gè)B信道和1個(gè)64KbpsD信道。我國電話局所提供ISDNPRI為30B+D。任務(wù)命令設(shè)置ISDN交換類型isdnswitchtypeswitchtype1接口設(shè)置interfacebri0設(shè)置PPP封裝encapsulationppp設(shè)置協(xié)議地址與電話號碼的映射dialermapprotocolnexthopaddress[namehostname][broadcast][dialstring]啟動PPP多連接pppmultilink設(shè)置啟動另一個(gè)B通道的閾值dialerloadthresholdload顯示ISDN有關(guān)信息showisdn{active|history|memory|services|status[dsl|interfacetypenumber]|timers}注：,國內(nèi)交換機(jī)一般為basicnet3。按區(qū)域分關(guān)鍵字交換機(jī)類型Australiabasicts013AustralianTS013switchesEuropebasic1tr6German1TR6ISDNswitchesbasicnwnet3NorwayNET3switches(phase1)basicnet3NET3ISDNswitches(UK,Denmark,andothernations)。coverstheEuroISDNEDSS1signallingsystemprimarynet5NET5switches(UKandEurope)vn2FrenchVN2ISDNswitchesvn3FrenchVN3ISDNswitchesJapannttJapaneseNTTISDNswitchesprimarynttJapaneseISDNPRIswitchesNorthAmericabasic5essATamp。Tbasicrateswitchesbasicdms100NTDMS100basicrateswitchesbasicni1NationalISDN1switchesprimary4essATamp。T4ESSswitchtypeforthe.(ISDNPRIonly)primary5essATamp。T5ESSswitchtypeforthe.(ISDNPRIonly)primarydms100NTDMS100switchtypeforthe.(ISDNPRIonly)NewZealandbasicnznet3NewZealandNet3switches（dialondemandrouting）實(shí)例:設(shè)置如下：Router1:hostnamerouter1userrouter2passwordcisco!isdnswitchtypebasicnet3!interfacebri0ipaddressencapsulationpppdialermapipnamerouter2572dialerloadthreshold80pppmultilinkdialergroup1pppauthenticationchap！dialerlist1protocolippermit!Router2:hostnamerouter2userrouter1passwordcisco!isdnswitchtypebasicnet3!interfacebri0ipaddressencapsulationpppdialermapipnamerouter1571dialerloadthreshold80pppmultilinkdialergroup1pppauthenticationchap！dialerlist1protocolippermit!CiscoCisco思科路由器同時(shí)支持回?fù)芄δ?，我們將Cisco思科路由器Router1作為CallbackServer,Router2作為CallbackClient。與回?fù)芟嚓P(guān)命令:任務(wù)命令映射協(xié)議地址和電話號碼，并在接口上使用在全局模式下定義的PPP回?fù)艿挠成漕悇e。dialermapprotocoladdressnamehostnameclassclassnamedialstring設(shè)置接口支持PPP回?fù)躳ppcallbackaccept在全局模式下為PPP回?fù)茉O(shè)置映射類別mapclassdialerclassname通過查找注冊在dialermap里的主機(jī)名來決定回?fù)?dialercallbackserver[username]設(shè)置接口要求PPP回?fù)躳ppcallbackrequest設(shè)置如下：Router1:hostnamerouter1userrouter2passwordcisco!isdnswitchtypebasicnet3!interfacebri0ipaddressencapsulationpppdialermapipnamerouter2classs3572dialerloadthreshold80pppcallbackacceptpppmultilinkdialergroup1pppauthenticationchap！mapclassdialers3dialercallbackserverusernamedialerlist1protocolippermit!Router2:hostnamerouter2userrouter1passwordcisco!isdnswitchtypebasicnet3!interfacebri0ipaddressencapsulationpppdialermapipnamerouter1571dialerloadthreshold80pppcallbackrequestpppmultilinkdialergroup1pppauthenticationchap！dialerlist1protocolippermit!相關(guān)調(diào)試命令：debugdialerdebugisdneventdebugisdnq921debugisdnq931debugpppauthenticationdebugppperrordebugpppnegotiationdebugppppacketshowdialershowisdnstatus舉例:執(zhí)行debugdialer命令觀察router2呼叫router1,router1回?fù)躵outer2的過程.router1debugdialerrouter2pingrouter100:03:50:%LINK3UPDOWN:InterfaceBRI0:1,changedstatetoup00:03:50:BRI0:1PPcallbackCallbackserverstartingtorouter257200:03:50:BRI0:1:disconnectingcall00:03:50:%LINK3UPDOWN:InterfaceBRI0:1,changedstatetodown00:03:50:BRI0:1:disconnectingcall00:03:50:BRI0:1:disconnectingcall00:03:51:%LINK3UPDOWN:InterfaceBRI0:2,changedstatetoup00:03:52:callbacktorouter2alreadystarted00:03:52:BRI0:2:disconnectingcall00:03:52:%LINK3UPDOWN:InterfaceBRI0:2,changedstatetodown00:03:52:BRI0:2:disconnectingcall00:03:52:BRI0:2:disconnectingcall00:04:05::Callbacktimerexpired00:04:05:BRI0:beginningcallbacktorouter257200:04:05:BRI0:Attemptingtodial57200:04:05:Freeingcallbacktorouter257200:04:05:%LINK3UPDOWN:InterfaceBRI0:1,changedstatetoup00:04:05:BRI0:1:Nocallbacknegotiated00:04:05:%LINK3UPDOWN:InterfaceVirtualAccess1,changedstatetoup00:04:05:dialerProtocolupforVi100:04:06:%LINEPROTO5UPDOWN:LineprotocolonInterfaceBRI0:1,changedstatetoup00:04:06:%LINEPROTO5UPDOWN:LineprotocolonInterfaceVirtualAccess1,changedstatetoup00:04:11:%ISDN6CONNECT:InterfaceBRI0:1isnowconnectedto572router1:,屬于保留地址，通過NAT地址翻譯功能，局域網(wǎng)用戶可以通過ISDN上263網(wǎng)訪問Internet。263的ISDN電話號碼為2633，用戶為263，口令為263，所涉及的命令如下表：任務(wù)命令指定接口通過PPP/IPCP地址協(xié)商獲得IP地址ipaddressnegotiated指定內(nèi)部和外部端口ipnat{inside|outside}使