NBMA网络OSPF non-roadcast

 

    1,OSPF模仿广播网络上运行方式;
    2,所有的接口都在同一子网;
    3,通常全互联拓扑,或手工选择DR和BDR,确保DR/BDR与所有路由器都直接相连;
    4,通过非广播接口扩散时,复制LSA,为每条PVC提供一个拷贝。更新被发送到邻居表中列出的每台路邻接由器。
    5,手工指定邻居;
    Router(config-router)#
    neighbor ip-address [priority number] [poll-interval number] [cost number] [database-filter all]
    *在non-broadcast模式中,只需在DR和BDR上配置命令neighbor。在中央-分支拓扑中,必须在中央路由器上配置命令neighbor,还必须将其优先级调高,使其成为DR;在分支路由器上,可以不配置neighbor,因为邻居自动发现。
    在全互联NBMA拓扑,除非使用命令ip ospf priority 静态地指定了DR和BDR,否则需要在所有路由器上配置命令neighbor
     
     
    实验:
    采用中央-分支的拓扑结构,将中央路由器设置为DR,在中央路由器上指定邻居。non-broadcast模式是Cisco在多点子接口和帧中继主接口上的默认模式。
     
     

     
     
    配置:
    FR:
    FR(config)#no ip routing
    FR(config)#frame-relay switching
     
    FR(config)#int s0/0
    FR(config-if)#no ip add
    FR(config-if)#no sh
    FR(config-if)#en fr
    FR(config-if)#frame-relay intf-ty dce
    FR(config-if)#clock rate 64000
    FR(config-if)#frame-relay lmi-type cisco
    FR(config-if)#frame-relay route 102 int s0/1 201
    FR(config-if)#frame-relay route 103 int s0/2 301
    FR(config-if)#exit
     
    FR(config)#int s0/1
    FR(config-if)#no sh
    FR(config-if)#no ip add
    FR(config-if)#en fr
    FR(config-if)#frame-relay intf-type dce
    FR(config-if)#clock rate 64000
    FR(config-if)#frame-relay lmi-type cisco
    FR(config-if)#frame-relay route 201 int s0/0 102
    FR(config-if)#exit
     
    FR(config)#int s0/2
    FR(config-if)#no ip add
    FR(config-if)#no sh
    FR(config-if)#en fr
    FR(config-if)#frame-relay intf-ty dce
    FR(config-if)#clock rate 64000
    FR(config-if)#frame-relay lmi-type cisco
    FR(config-if)#frame-relay route 301 int s0/0 103
    FR(config-if)#exit
     
    R1:
    R1(config)#int lo0
    R1(config-if)#ip add 1.1.1.1 255.255.255.0
    R1(config-if)#ip ospf net point-to-point
    R1(config-if)#exit
    R1(config)#int s0/0
    R1(config-if)#no ip add
    R1(config-if)#no sh
    R1(config-if)#en fra
    R1(config)#int s0/0.1 multipoint
    R1(config-subif)#ip add 10.10.10.1 255.255.255.0
    R1(config-subif)#frame-relay map ip 10.10.10.2 102 br                           
    R1(config-subif)#frame-relay map ip 10.10.10.3 103 br
    R1(config-subif)#no ip ospf net non-broadcast                                          //指定为non-broadcast模式
    R1(config-subif)#ip ospf priority 255                                                           //修改接口优先级,使中央路由器成为DR
     
    R1(config)#router ospf 1
    R1(config-router)#router-id 1.1.1.1
    R1(config-router)#net 1.1.1.0 0.0.0.255 area 0
    R1(config-router)#net 10.10.10.0 0.0.0.255 area 0
    R1(config-router)#neighbor 10.10.10.2          //手工指定邻居,在中央-分支拓扑中,只需将中央路由器设定为DR,并在中央路由器上指定邻居即可,分支路由器不需要再指定。
    R1(config-router)#neighbor 10.10.10.3
    R1(config-router)#exit
     
    R2:
    R2(config)#int lo 0
    R2(config-if)#ip add 2.2.2.2 255.255.255.0
    R2(config-if)#ip ospf net point-to-point
    R2(config-if)#exit
     
    R2(config)#int s0/0
    R2(config-if)#ip add 10.10.10.2 255.255.255.0
    R2(config-if)#no sh
    R2(config-if)#encapsulation frame-relay
    R2(config-if)#frame-relay map ip 10.10.10.1 201 br
    R2(config-if)#ip ospf network non-broadcast
    R2(config-if)#ip ospf priority 0                                               //将分支路由器接口优先级调为0,不参与选举,为DROTHER
     
    R2(config)#router ospf 1
    R2(config-router)#router-id 2.2.2.2
    R2(config-router)#net 2.2.2.0 0.0.0.255 area 0
    R2(config-router)#net 10.10.10.0 0.0.0.255 area 0
    R2(config-router)#exit
     
    R3:
    R2(config)#int lo 0
    R2(config-if)#ip add 3.3.3.3 255.255.255.0
    R2(config-if)#ip ospf net point-to-point
    R2(config-if)#exit
     
    R3(config)#int s0/0
    R3(config-if)#ip add 10.10.10.3 255.255.255.0
    R3(config-if)#no sh
    R3(config-if)#encapsulation frame-relay
    R3(config-if)#frame-relay map ip 10.10.10.1 301 br
    R3(config-if)#ip ospf network non-broadcast
    R3(config-if)#ip ospf priority 0    
     
     
     
    R3(config)#router ospf 1
    R3(config-router)#router-id 3.3.3.3
    R3(config-router)#net 3.3.3.0 0.0.0.255 area 0
    R3(config-router)#net 10.10.10.0 0.0.0.255 area 0
    R3(config-router)#exit
     
     
     
    验证:
    R1#sh ip ospf nei
     
    Neighbor ID     Pri   State           Dead Time   Address         Interface
    3.3.3.3           0   FULL/DROTHER    00:01:56    10.10.10.3      Serial0/0.1
    2.2.2.2           0   FULL/DROTHER    00:01:48    10.10.10.2      Serial0/0.1
     
    R2#sh ip ospf nei
     
    Neighbor ID     Pri   State           Dead Time   Address         Interface
    1.1.1.1         255   FULL/DR         00:01:56    10.10.10.1      Serial0/0
     
    R3#sh ip ospf nei
     
    Neighbor ID     Pri   State           Dead Time   Address         Interface
    1.1.1.1         255   FULL/DR         00:01:42    10.10.10.1      Serial0/0
     
    R1#sh ip ospf int s0/0.1
    Serial0/0.1 is up, line protocol is up
     Internet Address 10.10.10.1/24, Area 0
     Process ID 1, Router ID 1.1.1.1, Network Type NON_BROADCAST, Cost: 64
     Transmit Delay is 1 sec, State DR, Priority 255
     Designated Router (ID) 1.1.1.1, Interface address 10.10.10.1
     No backup designated router on this network
     Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
        oob-resync timeout 120
        Hello due in 00:00:24
     Supports Link-local Signaling (LLS)
     Index 2/2, flood queue length 0
     Next 0x0(0)/0x0(0)
     Last flood scan length is 1, maximum is 2
     Last flood scan time is 0 msec, maximum is 4 msec
     Neighbor Count is 2, Adjacent neighbor count is 2
        Adjacent with neighbor 3.3.3.3
        Adjacent with neighbor 2.2.2.2
     Suppress hello for 0 neighbor(s)
     
     
    R1#sh ip ro os
         2.0.0.0/24 is subnetted, 1 subnets
    O       2.2.2.0 [110/65] via 10.10.10.2, 00:05:33, Serial0/0.1
         3.0.0.0/24 is subnetted, 1 subnets
    O       3.3.3.0 [110/65] via 10.10.10.3, 00:05:33, Serial0/0.1
     
     
     
     
     
     
     
     
     
     

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