环境描述：
4台路由器，其中R2用来模拟帧中继云；R1的S0/0连接R2的S0/0，R3的S0/0连接R2的S0/1，R4的S0/0连接R2的S0/2；
 
配置命令：
1、将R2变为帧中继交换机
en
conf t
hostname fr-sw
frame-relay swithing
interface s0/0
no ip address
clock rate 128000
encapsulation frame-relay
frame-relay lmi-type cisco
frame-relay intf-type dce
frame-relay route 103 interface s0/1 301
frame-relay route 104 interface s0/2 401
no shutdown
interface s0/1
no ip address
clock rate 128000
encapsulation frame-relay
frame-relay lmi-type cisco
frame-relay intf-type dce
frame-relay route 301 interface s0/1 103
no shutdown
interface s0/0
no ip address
clock rate 128000
encapsulation frame-relay
frame-relay lmi-type cisco
frame-relay intf-type dce
frame-relay route 104 interface s0/0 401  
no shutdown
end
sh frame-relay route
 
R1
interface Loopback1
 ip address 1.1.1.1 255.255.255.0
!
interface Serial0/0
 no ip address
 encapsulation frame-relay
 serial restart-delay 0
 no frame-relay inverse-arp
!
interface Serial0/0.1 multipoint
 ip address 192.168.1.1 255.255.255.0
 ip ospf network point-to-multipoint
 frame-relay map ip 192.168.1.2 103 broadcast
 frame-relay map ip 192.168.1.3 104 broadcast
 no frame-relay inverse-arp
router ospf 1
 router-id 1.1.1.1
 log-adjacency-changes
 network 1.1.1.0 0.0.0.255 area 0
 network 192.168.1.0 0.0.0.255 area 0
R3
interface Loopback1
 ip address 3.3.3.3 255.255.255.0
!
interface Serial0/0
 ip address 192.168.1.2 255.255.255.0
 encapsulation frame-relay
 ip ospf network point-to-multipoint
 serial restart-delay 0
 frame-relay map ip 192.168.1.1 301 broadcast
 no frame-relay inverse-arp
router ospf 1
 router-id 3.3.3.3
 log-adjacency-changes
 network 3.3.3.0 0.0.0.255 area 0
 network 192.168.1.0 0.0.0.255 area 0
!
R4
interface Loopback1
 ip address 4.4.4.4 255.255.255.0
!
interface Serial0/0
 ip address 192.168.1.3 255.255.255.0
 encapsulation frame-relay
 ip ospf network point-to-multipoint
 serial restart-delay 0
 frame-relay map ip 192.168.1.1 401 broadcast
 no frame-relay inverse-arp
!
router ospf 1
 router-id 4.4.4.4
 log-adjacency-changes
 network 4.4.4.0 0.0.0.255 area 0
 network 192.168.1.0 0.0.0.255 area 0