Example for Configuring PIM GR

Procedure

1. Assign IP addresses to interfaces and configure a unicast routing protocol on each router.

   # Configure an IP address and mask for each interface of the routers according to Figure 4-24. Configure OSPF on RouterA, RouterB, and RouterC to ensure that the routers can communicate at the network layer. The configurations of RouterA and RouterB are similar to the configuration of RouterC, and are not mentioned here.

   <Huawei> system-view
   [Huawei] sysname RouterC
   [RouterC] interface gigabitethernet 1/0/0
   [RouterC-GigabitEthernet1/0/0] ip address 10.110.2.1 24
   [RouterC-GigabitEthernet1/0/0] quit
   [RouterC] interface gigabitethernet 2/0/0
   [RouterC-GigabitEthernet2/0/0] ip address 192.168.4.2 24
   [RouterC-GigabitEthernet2/0/0] quit
   [RouterC] ospf
   [RouterC-ospf-1] area 0
   [RouterC-ospf-1-area-0.0.0.0] network 10.110.2.0 0.0.0.255
   [RouterC-ospf-1-area-0.0.0.0] network 192.168.4.0 0.0.0.255
   [RouterC-ospf-1-area-0.0.0.0] quit
   [RouterC-ospf-1] quit

2. Enable GR for the unicast routing protocol on each router and set the GR period.

   # Enable GR for the unicast routing protocol on all the routers and set the GR period to 200 seconds. The configurations of RouterA and RouterB are similar to the configuration of RouterC, and are not mentioned here.

   [RouterC] ospf
   [RouterC-ospf-1] opaque-capability enable
   [RouterC-ospf-1] graceful-restart
   [RouterC-ospf-1] graceful-restart period 200
   [RouterC-ospf-1] quit

3. Enable multicast routing on the routers, enable PIM-SM on all the interfaces, and enable IGMP on the interface of RouterC connected to hosts.

   # Enable multicast routing on all the routers and enable PIM-SM on all interfaces of the routers. The configurations of RouterA and RouterB are similar to the configuration of RouterC, and are not mentioned here.

   [RouterC] multicast routing-enable
   [RouterC] interface gigabitethernet 1/0/0
   [RouterC-GigabitEthernet1/0/0] pim sm
   [RouterC-GigabitEthernet1/0/0] quit
   [RouterC] interface gigabitethernet 2/0/0
   [RouterC-GigabitEthernet2/0/0] pim sm
   [RouterC-GigabitEthernet2/0/0] quit

   # Enable IGMP on the interface of RouterC connected to the host.

   [RouterC] interface gigabitethernet 1/0/0
   [RouterC-GigabitEthernet1/0/0] igmp enable
   [RouterC-GigabitEthernet1/0/0] quit

4. Configure a static RP.

   To ensure high reliability of the RP, it is recommended that you set the static RP address to the IP address of a loopback interface, because a loopback interface is always up.

   # Configure the static RP on all the routers. The configurations of RouterA and RouterB are similar to the configuration of RouterC, and are not mentioned here.

   [RouterC] pim
   [RouterC-pim] static-rp 10.10.1.1
   [RouterC-pim] quit

5. Enable PIM GR and set the PIM GR period.

   # Enable PIM GR on RouterC and set the PIM GR period to 300 seconds.

   [RouterC] pim
   [RouterC-pim] graceful-restart
   [RouterC-pim] graceful-restart period 300
   [RouterC-pim] quit

6. Verify the configuration.

   # Multicast source 10.110.1.100 sends data to multicast group 225.1.1.1. HostA sends an IGMP Report message to join the multicast group and can receive multicast data from the multicast source. Before triggering an active/standby switchover on RouterC, run the display pim routing-table command on RouterB and RouterC to view the multicast routing tables. The command output is as follows:

   <RouterB> display pim routing-table
    VPN-Instance: public net
    Total 1 (*, G) entry; 1 (S, G) entry
   
    (*, 225.1.1.1)
        RP: 10.10.1.1
        Protocol: pim-sm, Flag: WC
        UpTime: 01:52:38
        Upstream interface: GigabitEthernet1/0/0
            Upstream neighbor: 192.168.2.1
            RPF prime neighbor: 192.168.2.1
        Downstream interface(s) information:
        Total number of downstreams: 1
            1: GigabitEthernet2/0/0
                Protocol: pim-sm, UpTime: 01:52:38, Expires: 00:02:53
   
    (10.110.1.100, 225.1.1.1)
        RP: 10.10.1.1
        Protocol: pim-sm, Flag: SPT ACT
        UpTime: 01:52:38
        Upstream interface: GigabitEthernet1/0/0
            Upstream neighbor: 192.168.2.1
            RPF prime neighbor: 192.168.2.1
        Downstream interface(s) information:
        Total number of downstreams: 1
            1: GigabitEthernet2/0/0
                Protocol: pim-sm, UpTime: 01:52:38, Expires: 00:03:03  

   <RouterC> display pim routing-table
    VPN-Instance: public net
    Total 1 (*, G) entry; 1 (S, G) entry
   
    (*, 225.1.1.1)
        RP: 10.10.1.1
        Protocol: pim-sm, Flag: WC
        UpTime: 01:51:24
        Upstream interface: GigabitEthernet2/0/0
            Upstream neighbor: 192.168.4.1
            RPF prime neighbor: 192.168.4.1
        Downstream interface(s) information:
        Total number of downstreams: 1
            1: GigabitEthernet1/0/0
                Protocol: pim-sm, UpTime: 01:51:24, Expires: -
   
    (10.110.1.100, 225.1.1.1)
        RP: 10.10.1.1
        Protocol: pim-sm, Flag: SPT ACT
        UpTime: 01:51:24
        Upstream interface: GigabitEthernet2/0/0
            Upstream neighbor: 192.168.4.1
            RPF prime neighbor: 192.168.4.1
        Downstream interface(s) information:
        Total number of downstreams: 1
            1: GigabitEthernet1/0/0
                Protocol: pim-sm, UpTime: 01:51:24, Expires: -
   

   # Trigger an active/standby on RouterC.

   [RouterC] slave switchover
   Warning: Are you sure to switch over?[Y/N]:Y
   

   # During the PIM GR process, run the display pim routing-table command on RouterB and RouterC to view the routing tables. The command output is as follows:

   <RouterB> display pim routing-table
    VPN-Instance: public net
    Total 1 (*, G) entry; 1 (S, G) entry
   
    (*, 225.1.1.1)
        RP: 10.10.1.1
        Protocol: pim-sm, Flag: WC
        UpTime: 02:52:38
        Upstream interface: GigabitEthernet1/0/0
            Upstream neighbor: 192.168.2.1
            RPF prime neighbor: 192.168.2.1
        Downstream interface(s) information:
        Total number of downstreams: 1
            1: GigabitEthernet2/0/0
                Protocol: pim-sm, UpTime: 02:52:38, Expires: 00:03:00
   
    (10.110.1.100, 225.1.1.1)
        RP: 10.10.1.1
        Protocol: pim-sm, Flag: SPT ACT
        UpTime: 02:52:38
        Upstream interface: GigabitEthernet1/0/0
            Upstream neighbor: 192.168.2.1
            RPF prime neighbor: 192.168.2.1
        Downstream interface(s) information:
        Total number of downstreams: 1
            1: GigabitEthernet2/0/0
                Protocol: pim-sm, UpTime: 02:52:38, Expires: 00:03:12  

   <RouterC> display pim routing-table
    VPN-Instance: public net
    Total 1 (*, G) entry; 1 (S, G) entry
   
    (*, 225.1.1.1)
        RP: 10.10.1.1
        Protocol: pim-sm, Flag: WC
        UpTime: 02:51:24
        Upstream interface: GigabitEthernet2/0/0
            Upstream neighbor: 192.168.4.1
            RPF prime neighbor: 192.168.4.1
        Downstream interface(s) information:
        Total number of downstreams: 1
            1: GigabitEthernet1/0/0
                Protocol: igmp, UpTime: 02:51:24, Expires: -
   
    (10.110.1.100, 225.1.1.1)
        RP: 10.10.1.1
        Protocol: pim-sm, Flag: SPT ACT
        UpTime: 02:51:24
        Upstream interface: GigabitEthernet2/0/0
            Upstream neighbor: 192.168.4.1
            RPF prime neighbor: 192.168.4.1
        Downstream interface(s) information:
        Total number of downstreams: 1
            1: GigabitEthernet1/0/0
                Protocol: pim-sm, UpTime: 02:51:24, Expires: -
   

   The preceding information shows that the downstream interface on RouterB remains unchanged after an active/standby switchover occurs on RouterC. After the active/standby switchover, RouterC sends the backup Join messages to the upstream device and maintains the multicast forwarding entries during the GR process. This ensures nonstop multicast data forwarding.

   When RouterC is restoring multicast routing entries after the active/standby switchover, users can still receive multicast data normally. Multicast services are not affected during this process.