ospf重分发默认路由无法进入路由表问题

机房内设备升级改造，核心交换机与3台互联网路由器对接，中间通过防火墙加固

 

网络改造完发现其中一台华为路由器分发的默认路由没有进入核心交换机的路由表中。 

show IP route

0.0.0.0/0 [110/1] via 10.108.50.105, 01:56:25, GigabitEthernet1/0/10

                [110/1] via 10.108.50.102, 02:03:50, GigabitEthernet2/0/21

 

查看ospf 数据库，发现3台路由器的默认路由通告正常发布，且收到的metric值也无异常；

show ip ospf database 

 

            OSPF Router with ID (10.108.52.1) (Process ID 1)

 

                Type-5 AS External Link States

 

Link ID         ADV Router      Age         Seq#       Checksum Tag

0.0.0.0         10.108.50.98    1763        0x80000009 0x00833A 1

0.0.0.0         10.108.50.102   1511        0x80000004 0x00B1EE 1

0.0.0.0         10.108.50.105   967         0x80000004 0x009FFD 1

 

show ip ospf database ex

 

            OSPF Router with ID (10.108.52.1) (Process ID 1)

 

                Type-5 AS External Link States

 

  LS age: 22

  Options: (No TOS-capability, No DC, Upward)

  LS Type: AS External Link

  Link State ID: 0.0.0.0 (External Network Number )

  Advertising Router: 10.108.50.98

  LS Seq Number: 8000000A

  Checksum: 0x813B

  Length: 36

  Network Mask: /0

        Metric Type: 2 (Larger than any link state path)

        MTID: 0 

        Metric: 1 

        Forward Address: 0.0.0.0

        External Route Tag: 1

 

  LS age: 1571

  Options: (No TOS-capability, DC, Upward)

  LS Type: AS External Link

  Link State ID: 0.0.0.0 (External Network Number )

  Advertising Router: 10.108.50.102

  LS Seq Number: 80000004

  Checksum: 0xB1EE

  Length: 36

  Network Mask: /0

        Metric Type: 2 (Larger than any link state path)

        MTID: 0 

        Metric: 1 

        Forward Address: 0.0.0.0

        External Route Tag: 1

 

  LS age: 1028

  Options: (No TOS-capability, DC, Upward)

  LS Type: AS External Link

  Link State ID: 0.0.0.0 (External Network Number )

  Advertising Router: 10.108.50.105

  LS Seq Number: 80000004

  Checksum: 0x9FFD

  Length: 36

  Network Mask: /0

        Metric Type: 2 (Larger than any link state path)

        MTID: 0 

        Metric: 1 

        Forward Address: 0.0.0.0

        External Route Tag: 1

查看交换机对接路由器的接口发现，接口的cost值不同，导致交换机无法加载cost值较大的路由进入路由表；

show ip ospf interface g1/0/21

GigabitEthernet1/0/21 is up, line protocol is up (connected) 

  Internet Address 10.108.50.97/30, Area 0, Attached via Network Statement

  Process ID 1, Router ID 10.108.52.1, Network Type BROADCAST, Cost: 1

  Topology-MTID    Cost    Disabled    Shutdown      Topology Name

        0                     10         no            no                  Base

  Transmit Delay is 1 sec, State BDR, Priority 1

  Designated Router (ID) 10.108.50.98, Interface address 10.108.50.98

  Backup Designated router (ID) 10.108.52.1, Interface address 10.108.50.97

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

    oob-resync timeout 40

    Hello due in 00:00:09

  Supports Link-local Signaling (LLS)

  Cisco NSF helper support enabled

  IETF NSF helper support enabled

  Index 1/3/3, flood queue length 0

  Next 0x0(0)/0x0(0)/0x0(0)

  Last flood scan length is 2, maximum is 40

  Last flood scan time is 0 msec, maximum is 5 msec

  Neighbor Count is 1, Adjacent neighbor count is 1 

    Adjacent with neighbor 10.108.50.98  (Designated Router)

  Suppress hello for 0 neighbor(s)

 

因链路从1000mpbs变成了，100mbps，导致cost值增大，交换机选择其他两台路由器作为2条等价ospf路由条目进入路由表，经过对端口排查，网线存在重大问题，经过更换后，故障排除

 

三条路由均进入路由表

show ip rou

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP

       a - application route

       + - replicated route, % - next hop override, p - overrides from PfR

 

Gateway of last resort is 10.108.50.105 to network 0.0.0.0

 

O*E2  0.0.0.0/0 [110/1] via 10.108.50.105, 02:00:54, GigabitEthernet1/0/10

                [110/1] via 10.108.50.102, 02:08:19, GigabitEthernet2/0/21

                [110/1] via 10.108.50.98, 01:09:24, GigabitEthernet1/0/21