Cisco IOS OSPF邻居关系不能正常建立原因和解决

　　稍微对ospf的trouble shooting 总结了一下，有参考也有自己的心得。

　　(1)接口上没有激活ospf

　　就是在network语句的时候没有匹配清楚，比如配置了错误的反掩码不对，在show ip ospf interface的时候不会显示你希望激活的接口

　　使用show ip ospf interface来验证，这时候的邻居表是空的

>R2#show ip ospf neighbor
R2#

　　(2)物理层或者是数据链路层协议down.
   
　　使用show ip int brief 或者是 show int type nomber会导致ospf packet 封装失败。

　　(3)建立邻居的接口被passive掉

R2#show ip ospf interface Ethernet 0

Ethernet0 is up, line PRotocol is up
Internet Address 131.108.1.2/24, Area 0
Process ID 1, Router ID 131.108.1.2, Network Type BROADCAST, Cost: 10
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 131.108.1.2, Interface address 131.108.1.2
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
No Hellos (Passive interface)
Neighbor Count is 0, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)

　　(4)OSPF的hello组播地址被ACL Block

R1#
interface Ethernet0
ip address 131.108.1.1 255.255.255.0
ip access-group 100 in
!
access-list 100 permit tcp any any
access-list 100 permit udp any any
access-list 101 permit ip 131.108.1.0 0.0.0.255 host 224.0.0.5


R2#
interface Ethernet0
ip address 131.108.1.2 255.255.255.0
ip access-group 100 in
!
access-list 100 permit tcp any any
access-list 100 permit udp any any
access-list 101 permit ip 131.108.1.0 0.0.0.255 host 224.0.0.5


R2#debug ip packet 101 detail
IP packet debugging is on (detailed) for access list 101
IP: s=131.108.1.2 (Ethernet0), d=224.0.0.5, len 68, access denied, proto=89

这时候的邻居关系是INIT

R2#show ip ospf neighbor
Neighbor ID   Pri  State    Dead Time   Address         Interface
131.108.2.1    1  INIT/-   00:00:33    131.108.1.1     Ethernet0

R1#show access-list 101
Extended IP access list 101
    permit ip 131.108.1.0 0.0.0.3 host 224.0.0.5 (8 matches)
R1#debug ip packet 101 detail
IP packet debugging is on (detailed) for access list 101
R1#
IP: s=131.108.1.1 (local), d=224.0.0.5 (Ethernet0), len 60, sending broad/multicast,
proto
=89
IP: s=131.108.1.2 (Ethernet0), d=224.0.0.5, len 82, access denied, proto=89
IP: s=131.108.1.1 (local), d=224.0.0.5 (Ethernet0), len 60, sending broad/multicast,
proto
=89

IP: s=131.108.1.2 (Ethernet0), d=224.0.0.5, len 82,access denied, proto=89


　　(5)在broadcast链路上的子网掩码不匹配

　　(6)Hello/dead 间隔不匹配

　　(7)认证方式或者是认证密码不匹配

　　使用debug ip ospf adj 来查看,可以自己使用不同的情况来验证

　　(8)两台路由器处于不同的AREA

R1#debug ip ospf adj
OSPF adjacency events debugging is on
R1#
OSPF: Rcv pkt from 131.108.1.2, Ethernet0, area 0.0.0.0
      mismatch area 0.0.0.1 in the header

R2#show log
%OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be
        virtual-link but not found from 131.108.1.1, Ethernet0

　　(9)Stub/transit/NSSA 区域类型不匹配


　　这个是经常不小心会被忘记的。-v-

R1#debug ip ospf adj
OSPF adjacency events debugging is on
R1#
OSPF: Rcv hello from 131.108.0.1 area 1 from Ethernet0 131.108.1.2
OSPF: Hello from 131.108.1.2 with mismatched Stub/Transit area option bit

R1#debug ip ospf adj
OSPF adjacency events debugging is on
R1#
OSPF: Rcv hello from 131.108.0.1 area 1 from Ethernet0 131.108.1.2
OSPF: Hello from 131.108.1.2 with mismatched NSSA option bit


　　　(10)使用secondary IP来建立OSPF adjacency

R2#
interface FastEthernet0/0
ip address 131.108.1.2 255.255.255.0 secondary
ip address 131.108.4.2 255.255.255.0


R1#
interface Ethernet0
ip address 131.108.1.1 255.255.255.0

R2#debug ip ospf adj
OSPF adjacency events debugging is on
R2#
OSPF: Rcv pkt from 131.108.1.1, FastEthernet0/0, area 0.0.0.1 : src not on the same   network

　　(11)OSPF网络类型不匹配

　　（P-TO-P 和P-TO-M网络类型在hello时间间隔相同的情况下可以建立full关系，但是会缺少一条路由）
 可以做一下相关使用验证

　　(12)NBMA (Frame Relay, X.25, SMDS, and so on)网络类型上没有手动指定neighbor ip 地址

  邻居一直都是ATTEMPT状态

　　(13)在Router 两边的frame-relay map/dialer map语句声明中缺少了broadcast参数

更多的请看：http://www.qqread.com/windows/2003/index.Html