帧中继基本配置

阿宝和佳佳

帧中继基本配置

1、  实验目的

通过本实验可以掌握：

A.       帧中继的基本配置；

B.       帧中继的动态映射；

C.       帧中继的静态映射；

D.       帧中继上RIP的配置；

E.        接口水平分割的开启与关闭

2、  实验拓扑

3、  实验步骤

R1：

R1#conf t

Enterconfiguration commands, one per line. End with CNTL/Z.

R1(config)#ints1/0

R1(config-if)#ipaddress 192.168.134.1 255.255.255.0

R1(config-if)#encapsulation frame-relay    //接口封装帧中继

R1(config-if)#frame-relay lmi-type cisco    //配置接口的LMI类型

R1(config-if)#no shutdown

R1(config-if)#exit

R1(config)#int lo0

R1(config-if)#ip address 192.168.1.1 255.255.255.0

R1(config)#router rip

R1(config-router)#version 2

R1(config-router)#network 192.168.134.0

R1(config-router)#network 192.168.1.0

【提示】

如果采用的Cisco路由器的IOS是11.2及以后版本的，路由器可以自动协商LMI的类型，所以可以不配置。

R3：

R3#conf t

Enterconfiguration commands, one per line. End with CNTL/Z.

R3(config)#ints1/1

R3(config-if)#ipaddress 192.168.134.3 255.255.255.0

R3(config-if)#encapsulation frame-relay

R3(config-if)#frame-relay lmi-type cisco

R3(config-if)#no shutdown

R3(config-if)#exit

R3(config)#int lo0

R3(config-if)#ip address 192.168.3.1 255.255.255.0

R3(config-if)#no sh

R3(config-if)#exit

R3(config)#router rip

R3(config-router)#version 2

R3(config-router)#no auto-summary

R3(config-router)#network 192.168.134.0

R3(config-router)#network 192.168.3.0

R4：

R4#conf t

Enter configuration commands, one perline.  End with CNTL/Z.

R4(config)#int s1/2

R4(config-if)#ip address 192.168.134.4255.255.255.0

R4(config-if)#encapsulationframe-relay

R4(config-if)#frame-relaylmi-type cisco

R4(config-if)#no sh

R4(config-if)#exit

R4(config)#int lo0

R4(config-if)#ip address 192.168.4.1255.255.255.0

R4(config-if)#no sh

R4(config-if)#exit

R4(config)#router rip

R4(config-router)#version 2

R4(config-router)#network 192.168.134.0

R4(config-router)#network 192.168.4.0

R2：帧中继配置

R2#conf t

Enter configuration commands, one perline.  End with CNTL/Z.

R2(config)#frame-relay switching

R2(config)#int s1/0

R2(config-if)#clock rate 64000

R2(config-if)#encapsulationframe-relay

R2(config-if)#frame-relaylmi-type cisco

R2(config-if)#frame-relayintf-type dce

R2(config-if)#frame-relayroute 103 interface s1/1 301

R2(config-if)#frame-relayroute 104 interface s1/2 401

R2(config-if)#no sh

R2(config-if)#exit

R2(config)#int s1/1

R2(config-if)#clock rate 64000

R2(config-if)#encapsulationframe-relay

R2(config-if)#frame-relayroute 301 interface s1/0 103

R2(config-if)#frame-relayroute 304 interface s1/2 403

R2(config-if)#frame-relaylmi-type cisco

R2(config-if)#frame-relayintf-type dce

R2(config-if)#no sh

R2(config-if)#exit

R2(config)#int s1/2

R2(config-if)#clock rate 64000

R2(config-if)#encapsulationframe-relay

R2(config-if)#frame-relaylmi-type cisco

R2(config-if)#frame-relayintf-type dce

R2(config-if)#frame-relayroute 401 interface s1/0 104

R2(config-if)#frame-relayroute 403 interface s1/1 304

R2(config-if)#no sh

4、  实验调试

A、 show frame-relay map

该命令用来查看帧中继的映射

R1#show frame-relay map

Serial1/0 (up): ip 192.168.134.3 dlci103(0x67,0x1870), dynamic,

              broadcast,

              CISCO, status defined, active

Serial1/0 (up): ip 192.168.134.4 dlci104(0x68,0x1880), dynamic,

              broadcast,, status defined, active

R1#

R3#show frame-relay map

Serial1/1 (up): ip 192.168.134.1 dlci301(0x12D,0x48D0), dynamic,

              broadcast,

              CISCO, status defined, active

Serial1/1 (up): ip 192.168.134.4 dlci304(0x130,0x4C00), dynamic,

              broadcast,, status defined, active

R3#

R4#show frame-relay map

Serial1/2 (up): ip 192.168.134.1 dlci401(0x191,0x6410), dynamic,

              broadcast,, status defined, active

Serial1/2 (up): ip 192.168.134.3 dlci403(0x193,0x6430), dynamic,

              broadcast,, status defined, active

R4#

以上输出显示了帧中继逆向ARP的作用结果，表明路由器R1、R3和R4每个封装帧中继的接口都包含2条处于活动（active）状态的DLCI；每条记录都显示了远端的IP地址和本地的DLCI的映射关系；“broadcast”参数允许在PVC上传输广播货组播流量；“dynamic”表明是动态映射。

【提示】

以上实验我们注意到，每天路由器都不能ping通自己的串行口IP地址，但是可以ping通远端封装帧中继的串行口IP地址，因为自己的帧中继映射表中没有自己接口IP地址和DLCI的映射条目。采用逆向ARP做动态映射是解决不了该问题的，只有通过静态映射解决。

B、 show frame-relay pvc

R1#showframe-relay pvc

PVC Statistics for interface Serial1/0 (Frame Relay DTE)

//接口是帧中继的DTE

              Active     Inactive      Deleted       Static

  Local         2            0            0            0

  Switched      0            0            0            0

  Unused        0            0            0            0

//输出表明该接口有2条处于活跃状态的PVC

DLCI = 103, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE,INTERFACE = Serial1/0

//DLCI为103的PVC处于活跃状态，本地接口是S1/0，DLCI用途是LOCAL

DLCI = 104, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE,INTERFACE = Serial1/0

【技术要点】

PVC状态有如下3种，每种的含义如下所述：

                    i.             ACTIVE：表明PVC的状态是活跃的，表示成功的端对端（DTE到DTE）电路。

                  ii.             INACTIVE：表明成功连接到交换机，但在PVC的另一端未检测到DTE。

                 iii.             DELETED：表明为该DTE配置的DLCI被交换机视为对该接口无效，或PVC不存在。

C、 show frame-relay lmi

R1#showframe-relay lmi

LMI Statistics for interface Serial1/0 (Frame Relay DTE) LMITYPE = CISCO

//接口S1/0是帧中继的DTE，LMI类型为Cisco

  Invalid Unnumbered info 0             Invalid Prot Disc 0

  Invalid dummy Call Ref 0              Invalid Msg Type 0

  Invalid Status Message 0              Invalid Lock Shift 0

  Invalid Information ID 0              Invalid Report IE Len 0

  Invalid Report Request 0              Invalid Keep IE Len 0

  Num Status Enq. Sent325              Num Status msgs Rcvd 201

//路由器向帧中继交换机发送的LMI状态查询消息的数量以及路由器从帧中继交换机收到到LMI状态信息的数量

  Num ** Status Rcvd 0              Num Status Timeouts 124

  Last Full Status Req 00:00:20         Last Full Status Rcvd 00:00:20

R1#

D、 show ip route rip

R1#showip route rip

R    192.168.4.0/24 [120/1] via 192.168.134.4,00:00:08, Serial1/0

R    192.168.3.0/24 [120/1] via 192.168.134.4,00:00:08, Serial1/0

                    [120/1] via 192.168.134.3,00:00:19, Serial1/0

R1#

R3#sh iproute rip  

R    192.168.4.0/24 [120/1] via 192.168.134.4,00:00:24, Serial1/1

                    [120/1] via 192.168.134.1,00:00:21, Serial1/1

R    192.168.1.0/24 [120/1] via 192.168.134.4,00:00:24, Serial1/1

                    [120/1] via 192.168.134.1,00:00:21, Serial1/1

R3#

R4#sh iproute rip

R    192.168.1.0/24 [120/1] via 192.168.134.1,00:00:09, Serial1/2

R    192.168.3.0/24 [120/1] via 192.168.134.3,00:00:19, Serial1/2

                    [120/1] via 192.168.134.1,00:00:09, Serial1/2

R4#

以上输出表明各路由器的RIP路由信息正确。在本实验中，帧中继交换机在路由器R2上采用了PVC全互联的拓扑结构，但是在实际应用中，为了节省费用，一般采用中心-分支（Hub-and-Spoke）的拓扑结构，即只有分支到中心的PVC，假如路由器R1是中心路由器，路由器R2和R3是分支路由器，在路由器R2的配置修改如下：

R2(config)#int s1/1

R2(config-if)#no frame-relay route 304

R2(config)#int s1/2

R2(config-if)#no frame-relay route 403

此时再次查看路由表：

R1#showip route rip

R    192.168.4.0/24 [120/1] via 192.168.134.4,00:00:22, Serial1/0

R    192.168.3.0/24 [120/1] via 192.168.134.4,00:00:22, Serial1/0

                    [120/1] via 192.168.134.3,00:00:17, Serial1/0

R1#

R3#sh iproute rip

R    192.168.4.0/24 [120/1] via 192.168.134.1,00:00:22, Serial1/1

R    192.168.1.0/24 [120/1] via 192.168.134.1,00:00:22, Serial1/1

R3#

R4#sh iproute rip            

R    192.168.1.0/24 [120/1] via 192.168.134.1,00:00:07, Serial1/2

R    192.168.3.0/24 [120/1] via 192.168.134.1,00:00:07, Serial1/2

R4#

E、  配置帧中继静态映射

R1(config)#int s1/0

R1(config-if)#no frame-relay inverse-arp      //关闭逆向ARP，默认是开启的

R1(config-if)#frame-relay map ip192.168.134.3 103 broadcast

//配置帧中继静态映射

R1(config-if)#frame-relay map ip 192.168.134.4 104broadcast

R1(config-if)#frame-relay map ip192.168.134.1 104 broadcast

//配置到自己接口的IP地址的映射，目的是允许ping路由器该接口的IP地址

R3(config)#int s1/1

R3(config-if)#no frame-relay inverse-arp

R3(config-if)#frame-relay map ip 192.168.134.1 301 broadcast

R3(config-if)#frame-relay map ip 192.168.134.3 301 broadcast

R3(config-if)#frame-relay map ip 192.168.134.4 301broadcast

R4(config)#int s1/2

R4(config-if)#no frame-relay inverse-arp

R4(config-if)#frame-relay map ip 192.168.134.1 401broadcast

R4(config-if)#frame-relay map ip 192.168.134.3 401broadcast

R4(config-if)#frame-relay map ip 192.168.134.4 401 broadcast

                    i.             Show  frame-relay map

R1#showframe-relay map

Serial1/0(up): ip 192.168.134.1 dlci 104(0x68,0x1880), static,

              broadcast,

              CISCO, status defined, active

Serial1/0(up): ip 192.168.134.3 dlci 103(0x67,0x1870), static,

              broadcast,

              CISCO, status defined, active

Serial1/0(up): ip 192.168.134.4 dlci 104(0x68,0x1880), static,

              broadcast,

              CISCO, status defined, active

R1#

R3#showframe-relay map

Serial1/1(up): ip 192.168.134.1 dlci 301(0x12D,0x48D0), static,

              broadcast,

              CISCO, status defined, active

Serial1/1(up): ip 192.168.134.3 dlci 301(0x12D,0x48D0), static,

              broadcast,

              CISCO, status defined, active

Serial1/1(up): ip 192.168.134.4 dlci 301(0x12D,0x48D0), static,

              broadcast,

              CISCO, status defined, active

R3#

R4#showframe-relay map

Serial1/2(up): ip 192.168.134.1 dlci 401(0x191,0x6410), static,

              broadcast,

              CISCO, status defined, active

Serial1/2(up): ip 192.168.134.3 dlci 401(0x191,0x6410), static,

              broadcast,

              CISCO, status defined, active

Serial1/2(up): ip 192.168.134.4 dlci 401(0x191,0x6410), static,

              broadcast,

              CISCO, status defined, active

R4#

以上输出表明路由器R1、R3和R4每个封装了帧中继的接口下都采用静态映射

                  ii.             查看路由表

R1#sh iproute rip

R    192.168.4.0/24 [120/1] via 192.168.134.4,00:00:04, Serial1/0

R    192.168.3.0/24 [120/1] via 192.168.134.4,00:00:04, Serial1/0

                    [120/1] via 192.168.134.3,00:00:03, Serial1/0

R1#

R3#sh iproute rip

R    192.168.4.0/24 [120/1] via 192.168.134.1,00:00:10, Serial1/1

R    192.168.1.0/24 [120/1] via 192.168.134.1,00:00:10, Serial1/1

R3#

R4#sh iproute rip

R    192.168.1.0/24 [120/1] via 192.168.134.1,00:00:22, Serial1/2

R    192.168.3.0/24 [120/1] via 192.168.134.1,00:00:22, Serial1/2

R4#

以上输出表明各路由器的RIP路由信息正确，但是与上面动态映射实验的路由表相比，路由器R3的路由表中路由器R4环回口网络和路由器R4的路由表中路由器R3环回口网络的下一跳发生了变化，都指向路由器R1。

F、  水平分割问题：

R1#sh ipint s1/0

Serial1/0is up, line protocol is up

  Internet address is 192.168.134.1/24

  Broadcast address is 255.255.255.255

  Address determined by setup command

  MTU is 1500 bytes

  Helper address is not set

  Directed broadcast forwarding is disabled

  Multicast reserved groups joined: 224.0.0.9

  Outgoing access list is not set

  Inbound access list is not set

  Proxy ARP is enabled

  Local Proxy ARP is disabled

  Security level is default

  Split horizon isdisabled    //接口封装了帧中继哦，水平分割被自动关闭。

在R1上重新打开水平分割，在各路由器上检查路由表

R1(config)#int s1/0

R1(config-if)#ip split-horizon     //开启水平分割

R1#clear ip route *         //清除路由表

R1#sh iproute rip

R    192.168.4.0/24 [120/1] via 192.168.134.4,00:00:13, Serial1/0

R    192.168.3.0/24 [120/1] via 192.168.134.3,00:00:26, Serial1/0

R1#

//R1可以获得路由器R3和R4的环回口网络的路由

R3#sh iproute rip

R    192.168.1.0/24 [120/1] via 192.168.134.1,00:00:10, Serial1/1

R3#

      //路由器R3只能获得路由器R1的环回口网络的路由，这是由于路由器R1上水平分割开启后，路由器R1从路由器R4接收到路由器R4通告的路由后，受水平分割限制，不能从封装帧中继的接口发送出来，导致路由器R3没有接收到路由器R4上通告的路由。

R4#sh iproute rip

R    192.168.1.0/24 [120/1] via 192.168.134.1,00:00:09, Serial1/2

R4#

//同理，路由器R4也只能获得路由器R1的环回口网络的路由。

夏天的知了

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