Frame-relay 综合实验-2
实验拓扑：
实验要求：R1通过FR与R2和R3相连，R2 与R3之间没有相连，形成一个hub and spoke的拓扑，R1采用物理接口，R2与R3采用点对点子接口。
试验目的：配置完成后，R2 ping R3，观察是否可以ping通，与全部采用物理接口有什么区别？
实验配置：
R1：
R1(config)#int s1/0
R1(config-if)#enca frame-relay
R1(config-if)#ip add 172.16.3.3 255.255.255.0
R1(config-if)#no shu
R2：
R2(config)#int s1/0
R2(config-if)#enca frame-relay
R2(config-if)#no shu
R2(config-if)#exit
R2(config)#int s1/0.1 point-to-point
R2(config-subif)#frame-relay interface-dlci 103
R2(config-fr-dlci)#no shu
R2(config-subif)#exit
R3：
R3(config)#int s1/0
R3(config-if)#enca fram
R3(config-if)#no shu
R3(config-if)#exit
R3(config)#int s1/0.1 point-to-point
R3(config-subif)#ip add 172.16.3.2 255.255.255.0
R3(config-subif)#frame-relay interface-dlci 203
R3(config-fr-dlci)#no shu
OK，然后先在R1上show frame-relay map查看连同性：
R1#show fram map
Serial1/0 (up): ip 172.16.3.1 dlci 301(0x12D,0x48D0), dynamic,
broadcast,, status defined, active
Serial1/0 (up): ip 172.16.3.2 dlci 302(0x12E,0x48E0), dynamic,
broadcast,, status defined, active
全部都active，ping测试一下：
R1#ping 172.16.3.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.3.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 120/391/996 ms
R1#ping 172.16.3.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.3.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 120/181/260 ms
都通了，下面看R2与R3，在R2和R3上show fram map，注意观察输出的结果与R1有什么不同：
R2#show fram map
Serial1/0.1 (up): point-to-point dlci, dlci 103(0x67,0x1870), broadcast
status defined, active
R3#show fram map
Serial1/0.1 (up): point-to-point dlci, dlci 203(0xCB,0x30B0), broadcast
status defined, active
我们发现子接口show fram map显示的只有point-to-point dlci,和本地dlci 103，而R1上物理接口显示的是对端ip 172.16.3.1与本地dlci 301之间的映射，这点很重要，物理接口上的命令：frame-relay map，子接口上是没有这条命令的！！！下面在R2和R3之间ping测试，看是否可以ping通：
R2#ping 172.16.3.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.3.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 288/320/380 ms
R3#ping 172.16.3.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.3.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 360/393/432 ms
OK，可以直接ping通，而无需多余的配置。
总结：这个试验的目的是为了说明在hub and spoke拓扑环境中，采用点对点子接口的方式要比采用全物理接口的方式更加简单和扩展性强！
本文转自loveme2351CTO博客，原文链接：http://blog.51cto.com/loveme23/43335 ，如需转载请自行联系原作者
