四、Frame Relay
1. 帧中继技术
帧中继是一种高性能的WAN协议,它运行在OSI参考模型的物理层和数据链路层。它是一种数据包交换技术,是X.25的简化版本。它省略了X.25的一些强健功能,如提供窗口技术和数据重发技术,而是依靠高层协议提供纠错功能,这是因为帧中继工作在更好的WAN设备上,这些设备较之X.25的WAN设备具有更可靠的连接服务和更高的可靠性,它严格地对应于OSI参考模型的最低二层,而X.25还提供第三层的服务,所以,帧中继比X.25具有更高的性能和更有效的传输效率。
帧中继广域网的设备分为数据终端设备(DTE)和数据电路终端设备(DCE),Cisco路由器作为 DTE设备。
帧中继技术提供面向连接的数据链路层的通信,在每对设备之间都存在一条定义好的通信链路,且该链路有一个链路识别码。这种服务通过帧中继虚电路实现,每个帧中继虚电路都以数据链路识别码(DLCI)标识自己。DLCI的值一般由帧中继服务提供商指定。帧中继即支持PVC也支持SVC。
帧中继本地管理接口(LMI)是对基本的帧中继标准的扩展。它是路由器和帧中继交换机之间信令标准,提供帧中继管理机制。它提供了许多管理复杂互联网络的特性,其中包括全局寻址、虚电路状态消息和多目发送等功能。
2. 有关命令:
端口设置
任务 |
命令 |
设置Frame Relay封装 |
encapsulation frame-relay[ietf] 1 |
设置Frame Relay LMI类型 |
frame-relay lmi-type {ansi | cisco | q933a}2 |
设置子接口 |
interface interface-type interface-number.subinterface-number [multipoint|point-to-point] |
映射协议地址与DLCI |
frame-relay map protocol protocol-address dlci [broadcast]3 |
设置FR DLCI编号 |
frame-relay interface-dlci dlci [broadcast] |
注:1.若使Cisco路由器与其它厂家路由设备相连,则使用Internet工程任务组(IETF)规定的帧中继封装格式。
2.从Cisco IOS版本11.2开始,软件支持本地管理接口(LMI)“自动感觉”, “自动感觉”使接口能确定交换机支持的LMI类型,用户可以不明确配置LMI接口类型。
3.broadcast选项允许在帧中继网络上传输路由广播信息。
3. 帧中继point to point配置实例:
Router1:
interface serial 0
encapsulation frame-relay
!
interface serial 0.1 point-to-point
ip address 172.16.1.1 255.255.255.0
frame-reply interface-dlci 105
!
interface serial 0.2 point-to-point
ip address 172.16.2.1 255.255.255.0
frame-reply interface-dlci 102
!
interface serial 0.3 point-to-point
ip address 172.16.4.1 255.255.255.0
frame-reply interface-dlci 104
!
Router2:
interface serial 0
encapsulation frame-relay
!
interface serial 0.1 point-to-point
ip address 172.16.2.2 255.255.255.0
frame-reply interface-dlci 201
!
interface serial 0.2 point-to-point
ip address 172.16.3.1 255.255.255.0
frame-reply interface-dlci 203
!
相关调试命令:
show frame-relay lmi
show frame-relay map
show frame-relay pvc
show frame-relay route
show interfaces serial
go top
4. 帧中继 Multipoint 配置实例:
Router1:
interface serial 0
encapsulation frame-reply
!
interface serial 0.1 multipoint
ip address 172.16.1.2 255.255.255.0
frame-reply map ip 172.16.1.1 201 broadcast
frame-reply map ip 172.16.1.3 301 broadcast
frame-reply map ip 172.16.1.4 401 broadcast
!
Router2:
interface serial 0
encapsulation frame-reply
!
interface serial 0.1 multipoint
ip address 172.16.1.1 255.255.255.0
frame-reply map ip 172.16.1.2 102 broadcast
frame-reply map ip 172.16.1.3 102 broadcast
frame-reply map ip 172.16.1.4 102 broadcast
!
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
任务 |
命令 |
设置ISDN交换类型 |
isdn switch-type switch-type1 |
接口设置 |
interface bri 0 |
设置PPP封装 |
encapsulation ppp |
设置协议地址与电话号码的映射 |
dialer map protocol next-hop-address [name hostname] [broadcast] [dial-string] |
启动PPP多连接 |
ppp multilink |
设置启动另一个B通道的阈值 |
dialer load-threshold load |
显示ISDN有关信息 |
show isdn {active | history | memory | services | status [dsl | interface-type number] | timers} |
注:1.交换机类型如下表,国内交换机一般为basic-net3。
按区域分关键字 |
交换机类型 |
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 |
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:
任务 |
命令 |
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。 |
dialer map protocol address name hostname class classname dial-string |
设置接口支持PPP回拨 |
ppp callback accept |
在全局模式下为PPP回拨设置映射类别 |
map-class dialer classname |
通过查找注册在dialer map里的主机名来决定回拨. |
dialer callback-server [username] |
设置接口要求PPP回拨 |
ppp callback request |
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:
任务 |
命令 |
指定接口通过PPP/IPCP地址协商获得IP地址 |
ip address negotiated |
指定内部和外部端口 |
ip nat {inside | outside} |
使用ppp/pap作认证 |
ppp authentication pap callin |
指定接口属于拨号组1 |
dialer-group 1 |
定义拨号组1允许所有IP协议 |
dialer-list 1 protocol ip permit |
设定拨号,号码为2633 |
dialer string 2633 |
设定登录263的用户名和口令 |
ppp pap sent-username 263 password 263 |
设定默认路由 |
ip route 0.0.0.0 0.0.0.0 bri 0 |
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 |
ip nat inside source list 2 interface bri 0 overload |
设定访问列表2,允许所有协议 |
access-list 2 permit any |
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
!
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:
任务 |
命令 |
设置路由器系统名称 |
set system c765 |
允许路由器呼叫多个目的地 |
set multidestination on |
设置ISDN交换机类型为NET3 |
set switch net3 |
允许点到点间多条通道连接实现负载均衡 |
set ppp multilink on |
关掉桥接 |
set briding off |
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。 |
set user remotenet |
使用PPP/IPCP |
set ip framing none |
设置上网用户帐号 |
set ppp clientname 263 |
设置上网口令 |
set ppp password client Enter new Password: 263 Re-Type new Password: 263 |
不用PPP/CHAP或PAP做认证 |
set ppp authentication out none |
允许地址磋商 |
set ppp address negotiation local on |
设置地址翻译 |
set ip pat on |
设置默认路由 |
set ip route destination 0.0.0.0/0 gateway 0.0.0.0 |
设置ISP的电话号码 |
set number 2633 |
激活用户预制文件 |
set active |