实验31:帧中继基本配置、帧中继映射
1. 实验目的
通过本实验，读者可以掌握如下技能：
（1） 帧中继的基本配置
（2） 帧中继的动态映射
2. 实验拓扑
如图。
3. 实验步骤
r0(config)#no ip do loo
r0(config)#lin c 0
r0(config-line)#logg s
r0(config-line)#exec-t 00
r0(config-line)#exit
r0(config)#int s0/0
r0(config-if)#ip add 172.16.1.1 255.255.255.0
r0(config-if)#no sh
r0(config-if)#enc fra//“encapsulation frame-relay [ ietf ]”命令用来配置接口封装成帧中继，如果不加
ietf 参数，帧类型为cisco；如果加ietf 参数，则帧类型为ietf。
r0(config-if)#
*Mar 1 00:05:04.383: %LINK-3-UPDOWN: Interface Serial0/0, changed state to up
*Mar 1 00:05:05.387: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
r0(config-if)#do ping 172.16.1.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/54/140 ms
r0(config-if)#do sh frame-relay map
Serial0/0 (up): ip 172.16.1.3 dlci 101(0x65,0x1850), dynamic,
broadcast,, status defined, active
Serial0/0 (up): ip 172.16.1.2 dlci 102(0x66,0x1860), dynamic,
broadcast,, status defined, active
从命令输出中可以得到的信息有：
•172.16.1.3 映射到101
• Dynamic：表明是动态映射
• Broadcast：该PVC 允许广播包的通过
• Active：该PVC 是激活的
该命令是很重要的一条命令，如果在映射表中不存在映射，路由器将无法通信。可以使用名
命令“clear frame-relay inarp”命令清除无效的帧中继映射表。
r0(config-if)#do sh fram-relay route
r0(config-if)#do show frame pvc
PVC Statistics for interface Serial0/0 (Frame Relay DTE)
Active Inactive Deleted Static
Local 2 0 0 0
Switched 0 0 0 0
Unused 0 0 0 0
DLCI = 101, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0
input pkts 6 output pkts 6 in bytes 554
out bytes 554 dropped pkts 0 in pkts dropped 0
out pkts dropped 0 out bytes dropped 0
in FECN pkts 0 in BECN pkts 0 out FECN pkts 0
out BECN pkts 0 in DE pkts 0 out DE pkts 0
out bcast pkts 1 out bcast bytes 34
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
pvc create time 00:05:49, last time pvc status changed 00:05:49
从命令输出中可以得到的信息有：
???? DLCI = 101：表明该PVC 的DLCI 为101
???? PVC STATUS = ACTIVE：表明PVC 的状态是激活的；若PVC STATUS = INACTIVE——表
明远端路由器没正确配置；若PVC STATUS = DELETED——表明输入了错误的DLCI，
该PVC 不存在。
DLCI = 102, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0
input pkts 1 output pkts 1 in bytes 34
out bytes 34 dropped pkts 0 in pkts dropped 0
out pkts dropped 0 out bytes dropped 0
in FECN pkts 0 in BECN pkts 0 out FECN pkts 0
out BECN pkts 0 in DE pkts 0 out DE pkts 0
out bcast pkts 1 out bcast bytes 34
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
pvc create time 00:06:01, last time pvc status changed 00:06:01
r0(config-if)#do sh frame lmi
LMI Statistics for interface Serial0/0 (Frame Relay DTE) LMI TYPE = ANSI
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. Sent 56 Num Status msgs Rcvd 57
Num Update Status Rcvd 0 Num Status Timeouts 0
Last Full Status Req 00:00:10 Last Full Status Rcvd 00:00:10
r0(config-if)#
r1(config-if)#ip add 172.16.1.2 255.255.255.0
r1(config-if)#no sh
r1(config-if)#
*Mar 1 00:01:46.831: %LINK-3-UPDOWN: Interface Serial0/0, changed state to up
r1(config-if)#
*Mar 1 00:01:47.835: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
r1(config-if)#enc
*Mar 1 00:02:17.331: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down
r1(config-if)#encapsulation frame-relay
r1(config-if)#
*Mar 1 00:02:27.771: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
r1(config-if)#
r1(config-if)#do sh frame map
Serial0/0 (up): ip 172.16.1.1 dlci 301(0x12D,0x48D0), dynamic,
broadcast,, status defined, active
r1(config-if)#
r2(config)#int s0/0
r2(config-if)#ip add 172.16.1.3 255.255.255.0
r2(config-if)#no sh
r2(config-if)#
*Mar 1 00:00:58.275: %LINK-3-UPDOWN: Interface Serial0/0, changed state to up
r2(config-if)#
*Mar 1 00:00:59.279: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
r2(config-if)#
*Mar 1 00:01:27.095: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down
r2(config-if)#enc fra
r2(config-if)#
*Mar 1 00:02:35.867: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
r2(config-if)#do sh fram map
Serial0/0 (up): ip 172.16.1.1 dlci 201(0xC9,0x3090), dynamic,
broadcast,, status defined, active
r2(config-if)#
手工配置帧中继映射
默认情况下，路由器支持逆向ARP。若逆向ARP 未打开，可以用下列命令设置：
R1(config-if)#frame-relay inverse-arp
我们也可以关闭IARP，使用静态映射，命令如下：
“frame-relay map ip address dlci [ broadcast ]”
这里的broadcast 参数是允许该帧中继链路通过多播或广播包，如果帧中继链路上要运行路
由协议，该参数非常重要。读者自己试试
本文转自gauyanm 51CTO博客，原文链接：http://blog.51cto.com/gauyanm/238233，如需转载请自行联系原作者