OSPFv3 DR election configuration example

As shown in Figure 105:

• Configure router priority 100 for Switch A, the highest priority on the network, so it will become the DR.

• Configure router priority 2 for Switch C, the second highest priority on the network, so it will become the BDR.

• Configure router priority 0 for Switch B, so it cannot become a DR or BDR.

• Switch D uses the default router priority 1.

1. Configure IPv6 addresses for interfaces. (Details not shown.)

2. Configure basic OSPFv3:

   # On Switch A, enable OSPFv3 and specify the router ID as 1.1.1.1.

   <SwitchA> system-view
   [SwitchA] ospfv3
   [SwitchA-ospfv3-1] router-id 1.1.1.1
   [SwitchA-ospfv3-1] quit
   [SwitchA] interface vlan-interface 100
   [SwitchA-Vlan-interface100] ospfv3 1 area 0
   [SwitchA-Vlan-interface100] quit
   

   # On Switch B, enable OSPFv3 and specify the router ID as 2.2.2.2.

   <SwitchB> system-view
   [SwitchB] ospfv3
   [SwitchB-ospfv3-1] router-id 2.2.2.2
   [SwitchB-ospfv3-1] quit
   [SwitchB] interface vlan-interface 200
   [SwitchB-Vlan-interface200] ospfv3 1 area 0
   [SwitchB-Vlan-interface200] quit
   

   # On Switch C, enable OSPFv3 and specify the router ID as 3.3.3.3.

   <SwitchC> system-view
   [SwitchC] ospfv3
   [SwitchC-ospfv3-1] router-id 3.3.3.3
   [SwitchC-ospfv3-1] quit
   [SwitchC] interface vlan-interface 100
   [SwitchC-Vlan-interface100] ospfv3 1 area 0
   [SwitchC-Vlan-interface100] quit
   

   # On Switch D, enable OSPFv3 and specify the router ID as 4.4.4.4.

   <SwitchD> system-view
   [SwitchD] ospfv3
   [SwitchD-ospfv3-1] router-id 4.4.4.4
   [SwitchD-ospfv3-1] quit
   [SwitchD] interface vlan-interface 200
   [SwitchD-Vlan-interface200] ospfv3 1 area 0
   [SwitchD-Vlan-interface200] quit
   

   # Display neighbor information on Switch A. The switches have the same default DR priority 1, so Switch D (the switch with the highest router ID) is elected as the DR, and Switch C is the BDR.

   [SwitchA] display ospfv3 peer
   
                  OSPFv3 Process 1 with Router ID 1.1.1.1
   
    Area: 0.0.0.0
   -------------------------------------------------------------------------
    Router ID       Pri State             Dead-Time InstID Interface
    2.2.2.2         1   2-Way/DROther     00:00:36  0      Vlan200
    3.3.3.3         1   Full/BDR          00:00:35  0      Vlan100
    4.4.4.4         1   Full/DR           00:00:33  0      Vlan200
   

   # Display neighbor information on Switch D. The neighbor states are all full.

   [SwitchD] display ospfv3 peer
   
                  OSPFv3 Process 1 with Router ID 4.4.4.4
   
    Area: 0.0.0.0
   -------------------------------------------------------------------------
    Router ID       Pri State             Dead-Time InstID Interface
    1.1.1.1         1   Full/DROther      00:00:30  0      Vlan100
    2.2.2.2         1   Full/DROther      00:00:37  0      Vlan200
    3.3.3.3         1   Full/BDR          00:00:31  0      Vlan100
   

3. Configure router priorities for interfaces:

   # Set the router priority of VLAN-interface 100 to 100 on Switch A.

   [SwitchA] interface Vlan-interface 100
   [SwitchA-Vlan-interface100] ospfv3 dr-priority 100
   [SwitchA-Vlan-interface100] quit
   

   # Set the router priority of VLAN-interface 200 to 0 on Switch B.

   [SwitchB] interface vlan-interface 200
   [SwitchB-Vlan-interface200] ospfv3 dr-priority 0
   [SwitchB-Vlan-interface200] quit
   

   # Set the router priority of VLAN-interface 100 to 2 on Switch C.

   [SwitchC] interface Vlan-interface 100
   [SwitchC-Vlan-interface100] ospfv3 dr-priority 2
   [SwitchC-Vlan-interface100] quit
   

   # Display neighbor information on Switch A. Router priorities have been updated, but the DR and BDR are not changed.

   [SwitchA] display ospfv3 peer
   
                  OSPFv3 Process 1 with Router ID 1.1.1.1
   
    Area: 0.0.0.0
   -------------------------------------------------------------------------
    Router ID       Pri State             Dead-Time InstID Interface
    2.2.2.2         0   2-Way/DROther     00:00:36  0      Vlan200
    3.3.3.3         2   Full/BDR          00:00:35  0      Vlan200
    4.4.4.4         1   Full/DR           00:00:33  0      Vlan200
   

   # Display neighbor information on Switch D. Switch D is still the DR.

   [SwitchD] display ospfv3 peer
   
                  OSPFv3 Process 1 with Router ID 4.4.4.4
   
    Area: 0.0.0.0
   -------------------------------------------------------------------------
    Router ID       Pri State             Dead-Time InstID Interface
    1.1.1.1         100 Full/DROther      00:00:30  0      Vlan100
    2.2.2.2         0   Full/DROther      00:00:37  0      Vlan200
    3.3.3.3         2   Full/BDR          00:00:31  0      Vlan100
   

4. Restart DR and BDR election:

   # Use the shutdown and undo shutdown commands on interfaces to restart DR and BDR election. (Details not shown.)

   # Display neighbor information on Switch A. The output shows that Switch C becomes the BDR.

   [SwitchA] display ospfv3 peer
   
                  OSPFv3 Process 1 with Router ID 1.1.1.1
   
    Area: 0.0.0.0
   -------------------------------------------------------------------------
    Router ID       Pri State             Dead-Time InstID Interface
    2.2.2.2         0   Full/DROther      00:00:36  0      Vlan200
    3.3.3.3         2   Full/BDR          00:00:35  0      Vlan100
    4.4.4.4         1   Full/DROther      00:00:33  0      Vlan200
   

   # Display neighbor information on Switch D.

   [SwitchD] display ospfv3 peer
   
                  OSPFv3 Process 1 with Router ID 4.4.4.4
   
    Area: 0.0.0.0
   -------------------------------------------------------------------------
    Router ID       Pri State             Dead-Time InstID Interface
    1.1.1.1         100 Full/DR           00:00:30  0      Vlan100
    2.2.2.2         0   2-Way/DROther     00:00:37  0      Vlan200
    3.3.3.3         2   Full/BDR          00:00:31  0      Vlan100
   

   The output shows that Switch A becomes the DR.