OSPF IP FRR示例

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组网需求

  1. 在R1与R3之间的链路出现故障的时候，R1的流量能够快速切换到备份链路
  2. 此时R1的流量通过R2进行转发

组网拓扑

OSPF快速收敛-OSPF IP FRR拓扑图

配置思路

  1. 配置路由器基本功能以及各个接口IP地址
  2. 配置OSPF协议，宣告路由，设置各个接口Cost值
  3. 在R1上使能OSPF IP FRR功能

配置命令

  1. 配置路由器基本功能以及各个接口IP地址

    • R1配置

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      sys
      sys R1

      int g0/0/0
        ip add 10.1.13.1 30
      int g0/0/1
        ip add 10.1.12.1 30

  • R2配置

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    sys R2

    int g0/0/1
      ip add 10.1.12.2 30
    int g0/0/2
      ip add 10.1.23.2 30

  • R3配置

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    sys R3

    int g0/0/0
      ip add 10.1.13.2 30
    int g0/0/1
      ip add 10.1.34.1 30
    int g0/0/2
      ip add 10.1.23.1 30

  • R4配置

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    sys R4

    int g0/0/1
      ip add 10.1.34.2 30

  1. 配置OSPF协议，宣告路由，设置各个接口Cost值

    • R1配置

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      sys
      ospf 1 router-id 10.1.1.1
        area 0
          network 10.1.13.0 0.0.0.3
          network 10.1.12.0 0.0.0.3
          
      int g0/0/0
          ospf cost 10
      int g0/0/1
          ospf cost 10

  • R2配置

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    sys
    ospf 1 router-id 10.1.2.2
      area 0
        network 10.1.23.0 0.0.0.3
        network 10.1.12.0 0.0.0.3
        
    int g0/0/1
        ospf cost 10
    int g0/0/2
        ospf cost 5

  • R3配置

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    ospf 1 router-id 10.1.3.3
      area 0
        network 10.1.13.0 0.0.0.3
        network 10.1.23.0 0.0.0.3
        network 10.1.34.0 0.0.0.3
        
    int g0/0/0
        ospf cost 10
    int g0/0/1
        ospf cost 5
    int g0/0/2
        ospf cost 5

  • R4配置

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    ospf 1 router-id 10.1.4.4
      area 0
        network 10.1.34.0 0.0.0.3
        
    int g0/0/1
        ospf cost 5

  1. 配置OSPF IP FRR

    • R1配置

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      ospf 1
        frr
          loop-free-alternate

查看结果

  1. 配置之前R4路由表

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    display ip routing-table protocol ospf

    <R4>dis ip routing-table protocol ospf
    Route Flags: R - relay, D - download to fib
    ------------------------------------------------------------------------------
    Public routing table : OSPF
             Destinations : 3        Routes : 3        

    OSPF routing table status : <Active>
             Destinations : 3        Routes : 3

    Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

          10.1.12.0/30  OSPF    10   3           D   10.1.34.1       GigabitEthernet
    0/0/1
          10.1.13.0/30  OSPF    10   2           D   10.1.34.1       GigabitEthernet
    0/0/1
          10.1.23.0/30  OSPF    10   2           D   10.1.34.1       GigabitEthernet
    0/0/1

  1. 配置Cost之后R4路由表

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    display ip routing-table

    <R4>dis ip routing-table 
    Route Flags: R - relay, D - download to fib
    ------------------------------------------------------------------------------
    Routing Tables: Public
             Destinations : 10       Routes : 10       

    Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

          10.1.12.0/30  OSPF    10   16          D   10.1.34.1       GigabitEthernet
    0/0/1
          10.1.13.0/30  OSPF    10   11          D   10.1.34.1       GigabitEthernet
    0/0/1
          10.1.23.0/30  OSPF    10   6           D   10.1.34.1       GigabitEthernet
    0/0/1
          10.1.34.0/30  Direct  0    0           D   10.1.34.2       GigabitEthernet
    0/0/1
          10.1.34.2/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
    0/0/1
          10.1.34.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
    0/0/1
          127.0.0.0/8   Direct  0    0           D   127.0.0.1       InLoopBack0
          127.0.0.1/32  Direct  0    0           D   127.0.0.1       InLoopBack0
    127.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
    255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0

  1. 配置FRR后，当链路中断后R1到R4的路由变化（路由由R1-R3-R4切换到R1-R2-R3-R4）

    • 链路中断前路由

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      tracert 10.1.34.2

      <R1>tracert 10.1.34.2

       traceroute to  10.1.34.2(10.1.34.2), max hops: 30 ,packet length: 40,press CTRL
      _C to break 

       1 10.1.13.2 40 ms  20 ms  20 ms 

       2 10.1.34.2 20 ms  20 ms  20 ms

  • 链路中断后路由

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    tracert 10.1.34.2

    <R1>tracert 10.1.34.2

     traceroute to  10.1.34.2(10.1.34.2), max hops: 30 ,packet length: 40,press CTRL
    _C to break 

     1 10.1.12.2 30 ms  10 ms  10 ms 

     2 10.1.23.1 20 ms  20 ms  30 ms 

     3 10.1.34.2 20 ms  20 ms  20 ms
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