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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 Update 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。
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