在NBMA环境下特别需要注意的是ospf网络类型的语句即：
R2511AS#sh run in s 1.10
Building configuration...

Current configuration : 279 bytes
!
interface Serial1.10 multipoint
 ip address 11.1.1.4 255.255.255.0
 no ip route-cache
 ip ospf network point-to-multipoint
 no ip mroute-cache
 frame-relay map ip 11.1.1.3 403 broadcast
 frame-relay map ip 11.1.1.4 406 broadcast
 frame-relay map ip 11.1.1.6 406 broadcast
end

R2511AS#
----------------------------------------------------------------------
R2511AS#sh run int s 1.11
Building configuration...

Current configuration : 164 bytes
!
interface Serial1.11 point-to-point
 ip address 12.1.1.1 255.255.255.0
 no ip route-cache
 ip ospf network point-to-point
 frame-relay interface-dlci 402  
end

R2511AS#
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分别是P2MP，P2P。两种网络类型。
配置完成后可用sh ip os nei ,sh ip os da,等show 命令来查看，sh ip os da 命令是查看OSPF链路数据库。查看数据库中没有应该出现得LSA.遇到问题用debug命令来查看在哪里出问题了。
deb ip os pa
deb ip pa
deb ip os adj
等命令。
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R2511AS#sh ip os in   
Serial1.10 is up, line protocol is up
  Internet Address 11.1.1.4/24, Area 0
  Process ID 1, Router ID 10.0.0.1, Network Type POINT_TO_MULTIPOINT, Cost: 64
  Transmit Delay is 1 sec, State POINT_TO_MULTIPOINT,
  Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
    Hello due in 00:00:10
  Index 1/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 2
  Last flood scan time is 12 msec, maximum is 16 msec
  Neighbor Count is 2, Adjacent neighbor count is 2
    Adjacent with neighbor 11.1.1.3
    Adjacent with neighbor 192.168.0.166
  Suppress hello for 0 neighbor(s)
Serial1.11 is up, line protocol is up
  Internet Address 12.1.1.1/24, Area 1
  Process ID 1, Router ID 10.0.0.1, Network Type POINT_TO_POINT, Cost: 64
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:01
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 4
  Last flood scan time is 4 msec, maximum is 8 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 192.168.0.43
  Suppress hello for 0 neighbor(s)
R2511AS#
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sh ip os interface,查看OSPF运行得接口。有助于排错。
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注意broadcast参数，如果没有加此参数，表明NBMA网络底层不具备广播能力，这样将会造成OSPF邻居建立不成功，无法得到路由。如果没有此参数，则需要手动建立OSPF的nei.
进入OSPF进程：
nei    [nei ip address]
这样OSPF将以UNICAST方式发送数据包。（OSPF默认是组播数据包，224.0.0.5,所有路由器之间，224.0.0.6DR BDR之间）