帧中继子接口配置
帧中继子接口
帧中继有两种类型的接口：主接口和子接口。其中子接口是一个逻辑结构，可以配置协议地址和虚电路等，一个物理接口可以有多个子接口。虽然子接口是逻辑结构，并不实际存在，但对于网络层而言，子接口和主接口是没有区别的，都可以配置虚电路与远端设备相连。帧中继的子接口又可以分为两种类型：点到点（point-to-point)子接口和点到多点(point-to-multipoint)子接口。点到点子接口用于连接单个远端目标，点到多点子接口用于连接多个远端目标。点到多点子接口在一个子接口上配置多条虚电路，每条虚电路都和它相连的远端网络地址建立一个地址映射，这样不同的虚电路就可以到达不同的远端而不会混淆。
地址映射的建立可以用手工配置的方法，也可以利用逆向地址解析协议来动态建立。点到点子接口和多点子接口配置虚电路及地址映射的方法是不同的。
点到点子接口：对点到点子接口而言，因为只有唯一的一个对端地址，所以在给子接口配置一条PVC 时实际已经确定了对端地址，不能配置静态地址映射，也不能动态学习地址映射。
多点子接口：对点到多点子接口，对端地址与本地DLCI映射可以通过配置静态地址映射，或者通过逆向地址解析协议来确定（Inverse ARP在主接口上配置即可）。如果要建立静态地址映射，则应该对每一条虚电路建立静态地址映射关系。
拓扑图
设备参数：
|
设备 |
接口 |
IP地址 |
子网掩码 |
默认网关 |
DLCI |
|
R1 |
S0/0/0 |
|
|
N/A |
102 |
|
S0/0/0.12 |
192.168.123.1 |
255.255.255.0 |
|||
|
R2 |
S0/0/0.21 |
192.168.123.2 |
255.255.255.0 |
N/A |
201 |
实验内容：
帧中继配置：
R1配置：
Router>enable
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#ho
Router(config)#hostname R1
R1(config)#int
R1(config)#interface s0/0/0
R1(config-if)#no ip address
R1(config-if)#encapsulation frame-relay
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#no shutdownR1(config-if)#
%LINK-5-CHANGED: Interface Serial0/0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0, changed state to up
R1(config)#interface s0/0/0.12 point-to-pointR1(config)#interface s0/0/0.12 point-to-point
R1(config-subif)#
%LINK-5-CHANGED: Interface Serial0/0/0.12, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0.12, changed state to up
R1(config-subif)#ip address 192.168.123.1 255.255.255.0
R1(config-subif)#frame-relay interface-dlci 102
R1(config-subif)#endR1(config-subif)#ip address 192.168.123.1 255.255.255.0
R1(config-subif)#frame-relay interface-dlci 102
R1(config-subif)#end
R1#
%SYS-5-CONFIG_I: Configured from console by console
R1#show frame-relay map
Serial0/0/0.12 (up): point-to-point dlci, dlci 102, broadcast, status defined, active
R1#ping 192.168.123.1
R1#ping 192.168.123.1Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.123.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/30/43 ms
R1#ping 192.168.123.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.123.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/18/29 ms
R1#
R2配置：
Router>enable
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#hostname R2
R2(config)#interface s0/0/0
R2(config-if)#no ip address
R2(config-if)#encapsulation frame-relay
R2(config-if)#no frame-relay inverse-arp
R2(config-if)#no shutdown
Router>enable
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#hostname R2
R2(config)#interface s0/0/0
R2(config-if)#no ip address
R2(config-if)#encapsulation frame-relay
R2(config-if)#no frame-relay inverse-arp
R2(config-if)#no shutdownR2(config-if)#
%LINK-5-CHANGED: Interface Serial0/0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0, changed state to up
R2(config-if)#exit
R2(config)#interface s0/0/0.12 point-to-pointR2(config)#interface s0/0/0.12 point-to-point
R2(config-subif)#
%LINK-5-CHANGED: Interface Serial0/0/0.12, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0.12, changed state to up
R2(config-subif)#ip address 192.168.123.2 255.255.255.0
R2(config-subif)#frame-relay interface-dlci 201
R2(config-subif)#no shutdown
R2(config-subif)#endR2(config-subif)#ip address 192.168.123.2 255.255.255.0
R2(config-subif)#frame-relay interface-dlci 201
R2(config-subif)#no shutdown
R2(config-subif)#end
R2#
%SYS-5-CONFIG_I: Configured from console by console
R2#show fr
R2#show frame-relay m
R2#show frame-relay map
Serial0/0/0.12 (up): point-to-point dlci, dlci 201, broadcast, status defined, active
R2#ping 192.168.123.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.123.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 10/16/19 ms
R2#ping 192.168.123.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.123.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 25/30/37 ms
R2#
不积跬步无以至千里，不积小流无以成江海；
千里之行，始于足下；
每天一个小实验。
