IS-IS与BGP交互示例

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组网需求

  1. Router A与Router B在同一个自治域，两个路由器之间使用IS-IS协议实现互联互通
  2. Router B与Router C建立EBGP关系
  3. 要求各个网段互联互通，AS 65009向AS 65008传递路由时，改变路由的Cost

网络拓扑

配置思路

  1. 路由器基础配置以及IP地址
  2. 配置IS-IS协议以及接口使能IS-IS协议
  3. 配置BGP协议
  4. 配置路由引入以及路由策略（修改Cost）

配置命令

  1. 路由器基础配置以及IP地址

    • Router A配置

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      sys Router A

      int g0/0/0
        ip add 10.1.1.1 30

  • Router B配置

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    sys Router B

    int g0/0/0
      ip add 10.1.1.2 30
    int g0/0/1
      ip add 10.2.1.1 30
    int LoopBack 0
      ip add 1.1.1.1 32

  • Router C配置

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    sys Router C

    int g0/0/1
      ip add 10.2.1.2 30
    int LoopBack 0
      ip add 2.2.2.2 32

  1. 配置IS-IS协议以及接口使能IS-IS协议

    • Router A配置

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      isis 1
        network-entity 10.0100.0100.1001.00
      q

      int g0/0/0
        isis enable 1
        isis small-hello

  • Router B配置

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    sys
    isis 1
      network-entity 10.0100.0100.1002.00
    q

    int g0/0/0
      isis enable 1
      isis small-hello

  1. 配置BGP协议

    • Router B配置

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      sys
      bgp 65008
        router-id 1.1.1.1
        peer 10.2.1.2 as-number 65009
        
        ipv4-family unicast
          network 10.2.1.0 30
          network 1.1.1.1 30

  • Router C配置

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    bgp 65009
      router-id 2.2.2.2
      peer 10.2.1.1 as-number 65008
      
      ipv4-family unicast
        network 10.2.1.0 30
        network 2.2.2.2 32

  1. 配置路由引入以及路由策略（修改Cost）

    • Router B配置

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      sys

      #配置BGP引入IS-IS
      bgp 65008
        import-route isis 1

      #bgp路径过滤器
      ip as-path-filter 1 permit 65009

      #配置路由策略
      route-policy RTC permit node 0
        if-match as-path-filter 1
        apply cost 20
        
      #配置IS-IS引入BGP
      isis 1
        import-route bgp route-policy RTC

  • Router C配置

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    #配置静态路由
    ip route-static 200.1.1.1 32 NULL 0

    #BGP中引入静态路由
    bgp 65009
      import-route static

查看命令

  1. IS-IS引入BGP路由（未使用路由策略）

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    dis ip routing-table

    Route Flags: R - relay, D - download to fib
    ------------------------------------------------------------------------------
    Routing Tables: Public
             Destinations : 9        Routes : 9        

    Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

            2.2.2.2/32  ISIS-L2 15   74          D   10.1.1.2        GigabitEthernet
    0/0/0
           10.1.1.0/30  Direct  0    0           D   10.1.1.1        GigabitEthernet
    0/0/0
           10.1.1.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
    0/0/0
           10.1.1.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
    0/0/0
          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
          200.1.1.1/32  ISIS-L2 15   74          D   10.1.1.2        GigabitEthernet
    0/0/0  #此处的Cost为74
    255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0

  1. IS-IS引入BGP路由（使用路由策略）

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    dis ip routing-table

    Route Flags: R - relay, D - download to fib
    ------------------------------------------------------------------------------
    Routing Tables: Public
             Destinations : 9        Routes : 9        

    Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

            2.2.2.2/32  ISIS-L2 15   94          D   10.1.1.2        GigabitEthernet
    0/0/0
           10.1.1.0/30  Direct  0    0           D   10.1.1.1        GigabitEthernet
    0/0/0
           10.1.1.1/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
    0/0/0
           10.1.1.3/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
    0/0/0
          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
          200.1.1.1/32  ISIS-L2 15   94          D   10.1.1.2        GigabitEthernet
    0/0/0  # 此处的Cost是94
    255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0

  1. BGP引入IS-IS路由

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    <Router C>dis ip routing-table 
    Route Flags: R - relay, D - download to fib
    ------------------------------------------------------------------------------
    Routing Tables: Public
             Destinations : 11       Routes : 11       

    Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

            1.1.1.1/32  EBGP    255  0          RD   10.2.1.1        GigabitEthernet
    0/0/1
            2.2.2.2/32  Direct  0    0           D   127.0.0.1       LoopBack0
           10.1.1.0/30  EBGP    255  0          RD   10.2.1.1        GigabitEthernet
    0/0/1  #引入IS-IS路由
           10.2.1.0/30  Direct  0    0           D   10.2.1.2        GigabitEthernet
    0/0/1
           10.2.1.2/32  Direct  0    0           D   127.0.0.1       GigabitEthernet
    0/0/1
           10.2.1.3/32  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
          200.1.1.1/32  Static  60   0           D   0.0.0.0         NULL0
    255.255.255.255/32  Direct  0    0           D   127.0.0.1       InLoopBack0
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