本文面向思科路由器初學(xué)者詳細(xì)的介紹了如何去進(jìn)行ISDN的配置，并且通過SHOW RUN去查看配置后的結(jié)果，同時向大家介紹實(shí)現(xiàn)DDR以及舉例說明如何去配置。

1.綜合數(shù)字業(yè)務(wù)網(wǎng)（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B信道和1個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B信道和1個D信道，總速率可達(dá)1.544Mbps，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B信道和1個64Kbps D信道，總速率可達(dá)2.048Mbps。我國電話局所提供ISDN PRI為30B+D。

2.基本命令

任務(wù)命令
設(shè)置ISDN交換類型isdn switch-type switch-type1
接口設(shè)置interface bri 0
設(shè)置PPP封裝encapsulation ppp
設(shè)置協(xié)議地址與電話號碼的映射dialer map protocol next-hop-address [name hostname] [broadcast] [dial-string]
啟動PPP多連接ppp multilink
設(shè)置啟動另一個B通道的閾值dialer load-threshold load
顯示ISDN有關(guān)信息show isdn {active | history | memory | services | status [dsl | interface-type number] | timers}

注：1.交換機(jī)類型如下表,國內(nèi)交換機(jī)一般為basic-net3。
按區(qū)域分關(guān)鍵字 交換機(jī)類型
Australia
basic-ts013 Australian TS013 switches
Europe
basic-1tr6 German 1TR6 ISDN switches
basic-nwnet3 Norway NET3 switches (phase 1)
basic-net3 NET3 ISDN switches (UK, Denmark, and other nations); covers the Euro-ISDN E-DSS1 signalling system
primary-net5 NET5 switches (UK and Europe)
vn2 French VN2 ISDN switches
vn3 French VN3 ISDN switches
Japan
ntt Japanese NTT ISDN switches
primary-ntt Japanese ISDN PRI switches
North America
basic-5ess AT&T basic rate switches
basic-dms100 NT DMS-100 basic rate switches
basic-ni1 National ISDN-1 switches
primary-4ess AT&T 4ESS switch type for the U.S. (ISDN PRI only)
primary-5ess AT&T 5ESS switch type for the U.S. (ISDN PRI only)
primary-dms100 NT DMS-100 switch type for the U.S. (ISDN PRI only)
New Zealand
basic-nznet3 New Zealand Net3 switches#p#

3.ISDN實(shí)現(xiàn)DDR（dial-on-demand routing）實(shí)例:

設(shè)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
!

CiscoCisco思科路由器同時支持回?fù)芄δ?，我們將Cisco思科路由器Router1作為Callback Server,Router2作為Callback Client。

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。dialer map protocol address name hostname class classname dial-string
設(shè)置接口支持PPP回?fù)躳pp callback accept
在全局模式下為PPP回?fù)茉O(shè)置映射類別map-class dialer classname
通過查找注冊在dialer map里的主機(jī)名來決定回?fù)? dialer callback-server [username]
設(shè)置接口要求PPP回?fù)躳pp callback request

設(shè)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
!
相關(guān)調(diào)試命令：
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#p#

舉例:
執(zhí)行debug dialer命令觀察router2呼叫router1,router1回?fù)躵outer2的過程.
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: BRI0:1PP 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訪問首都在線263網(wǎng)實(shí)例:

本地局部網(wǎng)地址為10.0.0.0/24,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ip address negotiated
指定內(nèi)部和外部端口ip nat {inside | outside}
使用ppp/pap作認(rèn)證ppp authentication pap callin
指定接口屬于撥號組1dialer-group 1
定義撥號組1允許所有IP協(xié)議dialer-list 1 protocol ip permit
設(shè)定撥號，號碼為2633dialer string 2633
設(shè)定登錄263的用戶名和口令ppp pap sent-username 263 password 263
設(shè)定默認(rèn)路由ip route 0.0.0.0 0.0.0.0 bri 0
設(shè)定符合訪問列表2的所有源地址被翻譯為bri 0所擁有的地址ip nat inside source list 2 interface bri 0 overload
設(shè)定訪問列表2，允許所有協(xié)議access-list 2 permit any

具體配置如下：
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
!
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

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