OSPF网络根据配置排错-V1.0.doc

10OSPF网络根据配置排错OSPF网络根据配置排错网络拓扑如图10.1所示，配置完成后发现从R1到R4和R5所带主机有时通有时不通，网络通信出现故障。图10.1 BENET网络拓扑图各路由器的配置如下所示：R1配置interface FastEthernet0/0 ip address 10.0.0.1 255.255.255.252! interface FastEthernet1/0 ip address 20.0.0.1 255.255.255.252!router ospf 1network 10.0.0.0 0.0.0.3 area 0 network 20.0.0.0 0.0.0.3 area 0R2配置interface FastEthernet0/0 ip address 10.0.0.2 255.255.255.252!interface FastEthernet1/0 ip address 30.0.0.1 255.255.255.0!router ospf 1network 10.0.0.0 0.0.0.3 area 0 network 30.0.0.0 0.0.0.255 area 1R3配置interface FastEthernet0/0 ip address 30.0.0.5 255.255.255.0!interface FastEthernet1/0 ip address 20.0.0.2 255.255.255.252!router ospf 1network 20.0.0.0 0.0.0.3 area 0 network 30.0.0.0 0.0.0.255 area 2R4配置interface FastEthernet0/0 ip address 30.0.0.2 255.255.255.0!router ospf 1network 30.0.0.0 0.0.0.255 area 1R5配置interface FastEthernet0/0 ip address 30.0.0.6 255.255.255.0!router ospf 1network 30.0.0.0 0.0.0.255 area 2在处理OSPF故障时，一般首先查看路由表，通过路由表发现路由异常；然后根据出现异常的路由条目的目的地址，检查所属路由器的配置、邻接关系等排除故障。由于R1到R4、R5出现通信问题，所以查看R1的路由表，如下所示： 20.0.0.0/30 is subnetted, 1 subnetsC 20.0.0.0 is directly connected, FastEthernet1/0 10.0.0.0/30 is subnetted, 1 subnetsC 10.0.0.0 is directly connected, FastEthernet0/0 30.0.0.0/24 is subnetted, 1 subnetsO IA 30.0.0.0 110/2 via 20.0.0.2, 00:32:40, FastEthernet1/0 110/2 via 10.0.0.2, 00:32:40, FastEthernet0/0发现路由表中出现了负载均衡的路由条目，但是在网络规划中没有负载均衡的要求。由于30.0.0.0/24网段出现故障，所以检查配置此网段的路由器。经检查检查配置发现接口地址的子网掩码配置有误，将/30的掩码误配置成/24的掩码导致的网络通信故障。网络管理员更改配置如下所示：R2配置：interface FastEthernet1/0 ip address 30.0.0.1 255.255.255.252R3配置：interface FastEthernet0/0 ip address 30.0.0.5 255.255.255.252R4配置：interface FastEthernet0/0 ip address 30.0.0.2 255.255.255.252R5配置：interface FastEthernet0/0 ip address 30.0.0.6 255.255.255.252更改配置完成后，再次查看路由表已经恢复正常，网络通信也已正常。当运行OSPF协议的网络出现故障时，查看LSDB也可以快速有效的判断问题，上述故障案例中也可以通过LSDB发现故障。当OSPF网络出现故障时，可以使用show ip ospf database命令R1查看LSDB，如下： OSPF Router with ID (10.0.0.1) (Process ID 1) Router Link States (Area 0)Link ID ADV Router Age Seq# Checksum Link count10.0.0.1 10.0.0.1 953 0x80000005 0x00CAFC 230.0.0.1 30.0.0.1 605 0x8000000A 0x0011C2 130.0.0.5 30.0.0.5 943 0x80000006 0x009723 1 Net Link States (Area 0)Link ID ADV Router Age Seq# Checksum10.0.0.1 10.0.0.1 1448 0x80000002 0x0048B320.0.0.2 30.0.0.5 943 0x80000002 0x00C60E Summary Net Link States (Area 0)Link ID ADV Router Age Seq# Checksum30.0.0.0 30.0.0.1 97 0x80000004 0x00F00B30.0.0.0 30.0.0.5 943 0x80000002 0x00DC1DR1的LSDB中粗体部分出现不同的路由器发送了相同的LSA，这时可以使用show ip ospf database summary命令进一步查看R1路由器收到的类型3的LSA信息如下： OSPF Router with ID (10.0.0.1) (Process ID 1) Summary Net Link States (Area 0) Routing Bit Set on this LSA LS age: 163 Options: (No TOS-capability, DC, Upward) LS Type: Summary Links(Network) Link State ID: 30.0.0.0 (summary Network Number) Advertising Router: 30.0.0.1 LS Seq Number: 80000004 Checksum: 0xF00B Length: 28 Network Mask: /24 TOS: 0 Metric: 1 Routing Bit Set on this LSA LS age: 1009 Options: (No TOS-capability, DC, Upward) LS Type: Summary Links(Network) Link State ID: 30.0.0.0 (summary Network Number) Advertising Router: 30.0.0.5 LS Seq Number: 80000002 Checksum