Cisco IOS OSPF邻居关系不能正常建立的原因和解决方法(2)
【导读】本文概述总结了Cisco IOS OSPF 邻居关系不能正常建立的原因和解决方法(10)使用secondary IP来建立OSPF adjacency R2#inte***ce FastEthernet0/0ip address 131.108.1.2 255.255.255.0 secondaryip address 131.108.4.2 255.255.255.0R1#inte***ce Ethernet0ip address 131.108.1.1 255.255.255.0R2#debug ip ospf adjOSPF adjacency events debugging is onR2#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(14)接口两边的MTU 不匹配在cisco ios 12.0.3中加入了对mtu的检测，而低于这个版本的ios会忽略mtu检测，需要查看router 的ios version，debug ip ospf adj的结果是发现有大量的dbd重传，出现loading的原因就是一边的router需要对mtu进行检测，而一边忽略。R2#debug ip ospf adjOSPF adjacency events debugging is onR2#OSPF: Retransmitting request to 131.108.2.1 on Serial0OSPF: Database request to 131.108.2.1OSPF: sent LS REQ packet to 131.108.1.1, length 12OSPF: Retransmitting request to 131.108.2.1 on Serial0解决方法是接口命令：mtu 4470而不是：ip mtu 4470这时候的状态是 loading 。R2#show ip ospf neighborNeighbor ID Pri State Dead Time Address Inte***ce131.108.2.1 1 LOADING/- 00:00:37 131.108.1.1 Serial0还有一种mtu不匹配的情况是邻居关系是EXSTART，由于两边的mtu都需要检测，而mtu大小又不匹配.R2#show ip ospf neighborNeighbor ID Pri State Dead Time Address Inte***ce131.108.2.1 1 EXSTART/- 00:00:33 131.108.1.1 Serial0R1#debug ip ospf adjOSPF: Retransmitting DBD to 131.108.1.2 on Serial0.1OSPF: Send DBD to 131.108.1.2 on Serial0.1 seq 0x1E55 opt 0x2 flag 0x7 len 32OSPF: Rcv DBD from 131.108.1.2 on Serial0.1 seq 0x22AB opt 0x2 flag 0x7 len 32 mtu 1500state EXSTARTOSPF: Nbr 131.108.1.2 has larger inte***ce MTU(15)在broadcast网络上需要选举dr，而这时候两边的优先级又都是0(16)在Asynchronous Inte***ces上的OSPF邻居关系R1#inte***ce Async1description ASYNC LINE TO R2ip address 131.108.1.1 255.255.255.0encapsulation pppasync mode dedicateddialer in-banddialer map ip 131.108.1.2 name Router2 broadcastdialer-group 1ppp authentication chapR2#inte***ce Async1description ASYNC LINE TO R1ip address 131.108.1.2 255.255.255.0encapsulation pppasync mode dedicateddialer in-banddialer map ip 131.108.1.1 name Router2 broadcastdialer-group 1ppp authentication chap解决方法是在两个使用async default routing 或者asyn 1/2 12下一页尾页
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