OSPF FRR BFD联动示例

组网需求

1. 快速感知OSPF的链路中断
2. 快速将路由切换到备份链路

组网拓扑

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
4. 在R1与R3的链路之间配置BFD

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

     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

  sys
  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

  sys
  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

  sys
  sys R4
  
  int g0/0/1
    ip add 10.1.34.2 30

2. 配置OSPF协议，宣告路由，设置各个接口Cost值

   • R1配置

     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

  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

  sys
  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

  sys
  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

3. 配置OSPF IP FRR

   • R1配置

     sys
     ospf 1
       frr
         loop-free-alternate

4. 配置OSPF与BFD联动

   • R1配置

     sys
     bfd
     q
     
     ospf 1
       bfd all-interfaces enable
       bfd all-interfaces min-rx-interaval 100 min-tx-interval 100 detect-multicast 4
       
     int g0/0/0
       ospf bfd enable

• R3配置

  sys
  bfd
  q
  
  ospf 1
    bfd all-interfaces enable
    bfd all-interfaces min-rx-interaval 100 min-tx-interval 100 detect-multicast 4
    
  int g0/0/0
    ospf bfd enable

查看命令

1. 查看BFD会话状态

   display bfd session all
   
   <R1>dis bfd session all
   --------------------------------------------------------------------------------
   Local Remote     PeerIpAddr      State     Type        InterfaceName            
   --------------------------------------------------------------------------------
   
   8193  0          10.1.12.2       Down      D_IP_IF     GigabitEthernet0/0/1     
   8196  8196       10.1.13.2       Up        D_IP_IF     GigabitEthernet0/0/0     
   --------------------------------------------------------------------------------
        Total UP/DOWN Session Number : 1/1

2. 查看OSPF与BFD联动的会话状态

   display ospf bfd session all
   
   <R1>dis ospf bfd session all
   
   	 OSPF Process 1 with Router ID 10.1.1.1
     Area 0.0.0.0 interface 10.1.13.1(GigabitEthernet0/0/0)'s BFD Sessions
   
    NeighborId:10.1.3.3         AreaId:0.0.0.0          Interface:GigabitEthernet0/
   0/0
    BFDState:up                 rx    :1000             tx       :1000          
    Multiplier:3                BFD Local Dis:8196      LocalIpAdd:10.1.13.1
    RemoteIpAdd:10.1.13.2       Diagnostic Info:No diagnostic information
   
     Area 0.0.0.0 interface 10.1.12.1(GigabitEthernet0/0/1)'s BFD Sessions
   
    NeighborId:10.1.2.2         AreaId:0.0.0.0          Interface:GigabitEthernet0/
   0/1
    BFDState:down               rx    :11999            tx       :11999         
    Multiplier:0                BFD Local Dis:8193      LocalIpAdd:10.1.12.1
    RemoteIpAdd:10.1.12.2       Diagnostic Info:No diagnostic information

3. 当链路中断，BFD快速感知，并由FRR切换到备用链路

   • 中断前，路由使用主链路

     <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 20 ms  30 ms  10 ms 
     
      2 10.1.34.2 20 ms  30 ms  20 ms

• 链路中断，BFD快速感知，FRR切换到备用链路

  May 13 2022 10:37:09-08:00 R1 %%01BFD/4/STACHG_TODWN(l)[0]:BFD session changed t
  o Down. (SlotNumber=0, Discriminator=69206016, Diagnostic=DetectDown, Applicatio
  ns=OSPF, ProcessPST=False, BindInterfaceName=GigabitEthernet0/0/0, InterfacePhys
  icalState=Up, InterfaceProtocolState=Up) 
  <R1>
  May 13 2022 10:37:09-08:00 R1 %%01OSPF/3/NBR_CHG_DOWN(l)[1]:Neighbor event:neigh
  bor state changed to Down. (ProcessId=256, NeighborAddress=3.3.1.10, NeighborEve
  nt=KillNbr, NeighborPreviousState=Full, NeighborCurrentState=Down) 
  <R1>
  May 13 2022 10:37:09-08:00 R1 %%01OSPF/3/NBR_DOWN_REASON(l)[2]:Neighbor state le
  aves full or changed to Down. (ProcessId=256, NeighborRouterId=3.3.1.10, Neighbo
  rAreaId=0, NeighborInterface=GigabitEthernet0/0/0,NeighborDownImmediate reason=N
  eighbor Down Due to Kill Neighbor, NeighborDownPrimeReason=BFD Session Down, Nei
  ghborChangeTime=2022-05-13 10:37:09-08:00) 
  <R1>
  May 13 2022 10:37:11-08:00 R1 %%01IFPDT/4/IF_STATE(l)[3]:Interface GigabitEthern
  et0/0/0 has turned into DOWN state.
  <R1>
  May 13 2022 10:37:11-08:00 R1 %%01IFNET/4/LINK_STATE(l)[4]:The line protocol IP 
  on the interface GigabitEthernet0/0/0 has entered the DOWN state. 
  
  
  // 链路切换到备用
  <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 20 ms  20 ms  30 ms 
  
   2 10.1.23.1 40 ms  20 ms  20 ms 
  
   3 10.1.34.2 40 ms  40 ms  40 ms