OSPF故障排除实例分析

王朝other·作者佚名  2008-05-31
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实例一 网络类型不一致

配置如下表所示:

ROUTE1#show ip ospf interface serial 1

Serial1 is up, line PRotocol is up

Internet Address 10.1.1.1/24, Area 0

Process ID 20, Router ID 10.1.2.1, Network Type BROADCAST, Cost: 64

Transmit Delay is 1 sec, State DR, Priority 1

Designated Router (ID) 10.1.2.1, Interface address 10.1.1.1

Backup Designated router (ID) 10.1.1.2, Interface address 10.1.1.2

Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Hello due in 00:00:08

Neighbor Count is 1, Adjacent neighbor count is 1

Adjacent with neighbor 10.1.1.2(Backup Designated Router)

Suppress hello for 0 neighbor(s)

ROUTE2#show ip ospf interface serial 1/1

Serial1/1 is up, line protocol is up

Internet Address 10.1.1.2/24, Area 0

Process ID 20, Router ID 10.1.1.2, 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 00:00:02

Neighbor Count is 1, Adjacent neighbor count is 1

Adjacent with neighbor 10.1.2.1

Suppress hello for 0 neighbor(s)

从上面可以看出,路由器Router1是配置broadcast模式,而路由器Roure2配置成点对点模块。这种网络类型的不匹配,导致了路由通告的不可达。

ROUTE1#show ip ospf database router 10.1.1.2

Adv Router is not-reachable

LS age: 418

Options: (No TOS-capability, DC)

LS Type: Router Links

Link State ID: 10.1.1.2

Advertising Router: 10.1.1.2

LS Seq Number: 80000002

Checksum: 0xFA63

Length: 60

Number of Links: 3

Link connected to: another Router (point-to-point)

(Link ID) Neighboring Router ID: 10.1.2.1

(Link Data) Router Interface address: 10.1.1.2

Number of TOS metrics: 0

TOS 0 Metrics: 64

Link connected to: a Stub Network

(Link ID) Network/subnet number: 10.1.1.0

(Link Data) Network Mask: 255.255.255.0

Number of TOS metrics: 0

TOS 0 Metrics: 64

ROUTE2#show ip ospf database router 10.1.2.1

Adv Router is not-reachable

LS age: 357

Options: (No TOS-capability, DC)

LS Type: Router Links

Link State ID: 10.1.2.1

Advertising Router: 10.1.2.1

LS Seq Number: 8000000A

Checksum: 0xD4AA

Length: 48

Number of Links: 2

Link connected to: a Transit Network

(Link ID) Designated Router address: 10.1.1.1

(Link Data) Router Interface address: 10.1.1.1

Number of TOS metrics: 0

TOS 0 Metrics: 64

可以看出,对于子网10.1.1.0/24, 路由器ROUTE2产生一个点对点连接,而路由器Router2则产生一个透过的连接,这就在链路状态数据库中产了不一致,从而导致路由信息不会出现在路由表中。

ROUTE2#show ip route

10.1.0.0/16 is variably subnetted, 3 subnets, 2 masks

C 10.1.1.0/24 is directly connected, Serial1/1

C 10.1.3.1/32 is directly connected, Loopback0

解决方案:

为了解决这个问题,需要将两边的网络类型配置为一致。既可以将Router1上的网络类型改为点对点,也可以将Router2上的网络类型改为broadcast.在这个例子中我们将Router1上的网络类型修改为点对点类型。

ROUTE1#configure terminal

ROUTE1(config)#interface serial 1

ROUTE1(config-if)#no ip ospf network broadcast

ROUTE1(config-if)#end

ROUTE1#show ip ospf interface serial 1

Serial1 is up, line protocol is up

Internet Address 10.1.1.1/24, Area 0

Process ID 20, Router ID 10.1.2.1, 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 00:00:04

Neighbor Count is 1, Adjacent neighbor count is 1

Adjacent with neighbor 10.1.1.2

Suppress hello for 0 neighbor(s)

至此,故障排除。

需要注重的是,假如有一端的接口是多接口,而另一端是子接口,那么需要将两边都修改为broadcast接口。

实例二、一端Unnumbered另一端Numbered

配置如下表:

点击查看大图

ROUTER1#show interface serial 1

Serial1 is up, line protocol is up

Hardware is cxBus Serial

Interface is unnumbered.Using address of Loopback0 (10.1.2.1)

ROUTER2#show interface serial 1/1

Serial1/1 is up, line protocol is up

Hardware is cxBus Serial

Internet address is 10.1.1.2/24

上面的输出显示出ROUTER1的Serial 1接口是个unnumbered 接口,使用Loopback0的地址,而ROUTER2的Serial 1/1则配置有IP地址。

ROUTER1#show ip ospf interface serial 1

Serial1 is up, line protocol is up

Internet Address 0.0.0.0/24, Area 0

Process ID 20, Router ID 10.1.2.1, 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 00:00:02

Neighbor Count is 1, Adjacent neighbor count is 1

Adjacent with neighbor 10.1.1.2

Suppress hello for 0 neighbor(s)

ROUTER2#show ip ospf interface serial 1/1

Serial1/1 is up, line protocol is up

Internet Address 10.1.1.2/24, Area 0

Process ID 20, Router ID 10.1.1.2, 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 00:00:02

Neighbor Count is 1, Adjacent neighbor count is 1

Adjacent with neighbor 10.1.2.1

Suppress hello for 0 neighbor(s)

从上面可以看出,两边的网络类型都是点对点的,出现问题的原因是一边是unnumbered 而另一边则配置有IP地址,这就造成了OSPF数据库中的不一致。

ROUTER1#show ip ospf database router 10.1.1.2

Adv Router is not-reachable

LS age: 418

Options: (No TOS-capability, DC)

LS Type: Router Links

Link State ID: 10.1.1.2

Advertising Router: 10.1.1.2

LS Seq Number: 80000002

Checksum: 0xFA63

Length: 60

Number of Links: 3

Link connected to: another Router (point-to-point)

(Link ID) Neighboring Router ID: 10.1.2.1

(Link Data) Router Interface address: 10.1.1.2

Number of TOS metrics: 0

TOS 0 Metrics: 64

ROUTER2#show ip ospf database router 10.1.2.1

Adv Router is not-reachable

LS age: 357

Options: (No TOS-capability, DC)

LS Type: Router Links

Link State ID: 10.1.2.1

 
 
 
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