五、ISDN
1. 综合数字业务网（ISDN）
综合数字业务网（ISDN）由数字电话和数据传输服务两部分组成，一般由电话局提供这种服务。ISDN的基本速率接口（BRI）服务提供2个B信道和1个D信道（2B+D）。BRI的B信道速率为64Kbps,用于传输用户数据。D信道的速率为16Kbps，主要传输控制信号。在北美和日本，ISDN的主速率接口（PRI）提供23个B信道和1个D信道，总速率可达1.544Mbps，其中D信道速率为64Kbps。而在欧洲、澳大利亚等国家，ISDN的PRI提供30个B信道和1个64Kbps D信道，总速率可达2.048Mbps。我国电话局所提供ISDN PRI为30B+D。
2. 基本命令
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任务
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命令
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设置ISDN交换类型
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isdn switch-type switch-type1
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接口设置
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interface bri 0
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设置PPP封装
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encapsulation ppp
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设置协议地址与电话号码的映射
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dialer map protocol next-hop-address [name hostname] [broadcast] [dial-string]
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启动PPP多连接
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ppp multilink
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设置启动另一个B通道的阈值
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dialer load-threshold load
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显示ISDN有关信息
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show isdn {active | history | memory | services | status [dsl | interface-type number] | timers}
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注：1.交换机类型如下表,国内交换机一般为basic-net3。
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按区域分关键字
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交换机类型
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Australia
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basic-ts013
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Australian TS013 switches
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Europe
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basic-1tr6
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German 1TR6 ISDN switches
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basic-nwnet3
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Norway NET3 switches (phase 1)
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basic-net3
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NET3 ISDN switches (UK, Denmark, and other nations); covers the Euro-ISDN E-DSS1 signalling system
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primary-net5
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NET5 switches (UK and Europe)
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vn2
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French VN2 ISDN switches
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vn3
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French VN3 ISDN switches
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Japan
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ntt
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Japanese NTT ISDN switches
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primary-ntt
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Japanese ISDN PRI switches
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North America
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basic-5ess
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AT&T basic rate switches
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basic-dms100
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NT DMS-100 basic rate switches
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basic-ni1
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National ISDN-1 switches
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primary-4ess
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AT&T 4ESS switch type for the U.S. (ISDN PRI only)
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primary-5ess
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AT&T 5ESS switch type for the U.S. (ISDN PRI only)
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primary-dms100
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NT DMS-100 switch type for the U.S. (ISDN PRI only)
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New Zealand
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basic-nznet3
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New Zealand Net3 switches
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3. ISDN实现DDR（dial-on-demand routing）实例:
设置如下：
Router1:
hostname router1
user router2 password cisco
!
isdn switch-type basic-net3
!
interface bri 0
ip address 192.200.10.1 255.255.255.0
encapsulation ppp
dialer map ip 192.200.10.2 name router2 572
dialer load-threshold 80
ppp multilink
dialer-group 1
ppp authentication chap
！
dialer-list 1 protocol ip permit
!
Router2:
hostname router2
user router1 password cisco
!
isdn switch-type basic-net3
!
interface bri 0
ip address 192.200.10.2 255.255.255.0
encapsulation ppp
dialer map ip 192.200.10.1 name router1 571
dialer load-threshold 80
ppp multilink
dialer-group 1
ppp authentication chap
！
dialer-list 1 protocol ip permit
!
Cisco路由器同时支持回拨功能，我们将路由器Router1作为Callback Server,Router2作为Callback Client。
与回拨相关命令:
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任务
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命令
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映射协议地址和电话号码，并在接口上使用在全局模式下定义的PPP回拨的映射类别。
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dialer map protocol address name hostname class classname dial-string
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设置接口支持PPP回拨
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ppp callback accept
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在全局模式下为PPP回拨设置映射类别
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map-class dialer classname
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通过查找注册在dialer map里的主机名来决定回拨.
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dialer callback-server [username]
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设置接口要求PPP回拨
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ppp callback request
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设置如下：
Router1:
hostname router1
user router2 password cisco
!
isdn switch-type basic-net3
!
interface bri 0
ip address 192.200.10.1 255.255.255.0
encapsulation ppp
dialer map ip 192.200.10.2 name router2 class s3 572
dialer load-threshold 80
ppp callback accept
ppp multilink
dialer-group 1
ppp authentication chap
！
map-class dialer s3
dialer callback-server username
dialer-list 1 protocol ip permit
!
Router2:
hostname router2
user router1 password cisco
!
isdn switch-type basic-net3
!
interface bri 0
ip address 192.200.10.2 255.255.255.0
encapsulation ppp
dialer map ip 192.200.10.1 name router1 571
dialer load-threshold 80
ppp callback request
ppp multilink
dialer-group 1
ppp authentication chap
！
dialer-list 1 protocol ip permit
!
相关调试命令：
debug dialer
debug isdn event
debug isdn q921
debug isdn q931
debug ppp authentication
debug ppp error
debug ppp negotiation
debug ppp packet
show dialer
show isdn status
举例:执行debug dialer命令观察router2呼叫router1,router1回拨router2的过程.
router1#debug dialer
router2#ping 192.200.10.1
router1#
00:03:50: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up
00:03:50: BRI0:1:PPP callback Callback server starting to router2 572
00:03:50: BRI0:1: disconnecting call
00:03:50: %LINK-3-UPDOWN: Interface BRI0:1, changed state to down
00:03:50: BRI0:1: disconnecting call
00:03:50: BRI0:1: disconnecting call
00:03:51: %LINK-3-UPDOWN: Interface BRI0:2, changed state to up
00:03:52: callback to router2 already started
00:03:52: BRI0:2: disconnecting call
00:03:52: %LINK-3-UPDOWN: Interface BRI0:2, changed state to down
00:03:52: BRI0:2: disconnecting call
00:03:52: BRI0:2: disconnecting call
00:04:05: : Callback timer expired
00:04:05: BRI0:beginning callback to router2 572
00:04:05: BRI0: Attempting to dial 572
00:04:05: Freeing callback to router2 572
00:04:05: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up
00:04:05: BRI0:1: No callback negotiated
00:04:05: %LINK-3-UPDOWN: Interface Virtual-Access1, changed state to up
00:04:05: dialer Protocol up for Vi1
00:04:06: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state
to up
00:04:06: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access1, chang
ed state to up
00:04:11: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 572
#router1
4. ISDN访问首都在线263网实例:
本地局部网地址为10.0.0.0/24,属于保留地址，通过NAT地址翻译功能，局域网用户可以通过ISDN上263网访问Internet。263的ISDN电话号码为2633，用户为263，口令为263，所涉及的命令如下表：
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任务
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命令
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指定接口通过PPP/IPCP地址协商获得IP地址
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ip address negotiated
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指定内部和外部端口
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ip nat {inside | outside}
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使用ppp/pap作认证
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ppp authentication pap callin
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指定接口属于拨号组1
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dialer-group 1
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定义拨号组1允许所有IP协议
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dialer-list 1 protocol ip permit
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设定拨号，号码为2633
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dialer string 2633
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设定登录263的用户名和口令
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ppp pap sent-username 263 password 263
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设定默认路由
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ip route 0.0.0.0 0.0.0.0 bri 0
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设定符合访问列表2的所有源地址被翻译为bri 0所拥有的地址
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ip nat inside source list 2 interface bri 0 overload
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设定访问列表2，允许所有协议
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access-list 2 permit any
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具体配置如下：
hostname Cisco2503
!
isdn switch-type basic-net3
!
ip subnet-zero
no ip domain-lookup
ip routing
!
interface Ethernet 0
ip address 10.0.0.1 255.255.255.0
ip nat inside
no shutdown
!
interface Serial 0
shutdown
no description
no ip address
!
interface Serial 1
shutdown
no description
no ip address
!
interface bri 0
ip address negotiated
ip nat outside
encapsulation ppp
ppp authentication pap callin
ppp multilink
dialer-group 1
dialer hold-queue 10
dialer string 2633
dialer idle-timeout 120
ppp pap sent-username 263 password 263
no cdp enable
no ip split-horizon
no shutdown
!
ip classless
!
! Static Routes
!
ip route 0.0.0.0 0.0.0.0 bri 0
!
! Access Control List 2
!
access-list 2 permit any
!
dialer-list 1 protocol ip permit
!
! Dynamic NAT
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ip nat inside source list 2 interface bri 0 overload
snmp-server community public ro
!
line console 0
exec-timeout 0 0
!
line vty 0 4
!
end
5. Cisco765M通过ISDN拨号上263
由于Cisco765的设置命令与我们常用的Cisco路由器的命令不同，所以以下列举了通过Cisco765上263访问Internet的具体命令行设置步骤。
>set system c765
c765> set multidestination on
c765> set switch net3
c765> set ppp multilink on
c765> cd lan
c765:LAN> set ip routing on
c765:LAN> set ip address 10.0.0.1
c765:LAN> set ip netmask 255.0.0.0
c765:LAN> set briding off
c765:LAN>cd
c765> set user remotenet
New user remotenet being created
c765:remotenet> set ip routing on
c765:remotenet> set bridging off
c765:remotenet> set ip framing none
c765:remotenet> set ppp clientname 263
c765:remotenet> set ppp password client
Enter new Password: 263
Re-Type new Password: 263
c765:remotenet> set ppp authentication out none
c765:remotenet> set ip address 0.0.0.0
c765:remotenet> set ip netmask 0.0.0.0
c765:remotenet> set ppp address negotiation local on
c765:remotenet> set ip pat on
c765:remotenet> set ip route destination 0.0.0.0/0 gateway 0.0.0.0
c765:remotenet> set number 2633
c765:remotenet> set active
命令描述如下：
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任务
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命令
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设置路由器系统名称
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set system c765
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允许路由器呼叫多个目的地
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set multidestination on
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设置ISDN交换机类型为NET3
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set switch net3
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允许点到点间多条通道连接实现负载均衡
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set ppp multilink on
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关掉桥接
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set briding off
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建立用户预制文件用于设置拨号连接参数- 可以设置多个用户预制文件用于相同的物理端口对应于不同的连接。
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set user remotenet
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使用PPP/IPCP
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set ip framing none
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设置上网用户帐号
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set ppp clientname 263
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设置上网口令
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set ppp password client
Enter new Password: 263
Re-Type new Password: 263
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不用PPP/CHAP或PAP做认证
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set ppp authentication out none
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允许地址磋商
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set ppp address negotiation local on
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设置地址翻译
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set ip pat on
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设置默认路由
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set ip route destination 0.0.0.0/0 gateway 0.0.0.0
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设置ISP的电话号码
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set number 2633
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激活用户预制文件
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set active
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