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RPT on an IPv6 PIM-SM Network Fails to Be Established

Fault Symptom

The RPT that provides services for ASM fails to be established. User hosts cannot receive multicast data.

Fault Analysis

This fault is commonly caused by one of the following:

  • The unicast route from multicast devices to the RP is unavailable.
  • The RP addresses of multicast devices are inconsistent.
  • The downstream interfaces of multicast devices do not receive any (*, G) Join message.
  • IPv6 PIM-SM is not enabled on interfaces.
  • The RPF route to the RP is incorrect, for example, a unicast routing loop occurs.
  • Configurations are incorrect, for example, the configurations of the MTU, or the multicast boundary are improper.

Procedure

  1. Check whether the IPv6 PIM routing table contains correct (*, G) entries.

    Run the display pim ipv6 routing-table ipv6-group-address command on the switch to check whether the IPv6 PIM routing table contains (*, G) entries of multicast group G.

    • If the IPv6 PIM routing table contains correct (*, G) entries, run the display multicast ipv6 forwarding-table ipv6-group-address command every 15 seconds to check whether the forwarding table contains (S, G) entries that correspond to (*, G) entries and whether the value of the Matched field in the command output keeps increasing.

      • If the forwarding table contains (S, G) entries and the value of the Matched field keeps increasing, data forwarding on the upstream devices is correct but data cannot be forwarded to downstream devices. In this case, check whether the TTL value is too small or a forwarding failure occurs.

      • If the forwarding table does not contain (S, G) entries or the value of the Matched field stops increasing:
        • If the local device is not an RP, it has not received any multicast data. Check whether the IPv6 PIM routing table on the upstream device contains correct (S, G) entries.

        • If the local device is the RP, the RPT has been established successfully. In this case, check whether the source's DR is registered successfully.

    • If the IPv6 PIM routing table does not contain correct (*, G) entries, go to step 2.

  2. Check whether the downstream interfaces of upstream devices receive Join messages.

    Run the display pim ipv6 control-message counters interface interface-type interface-number message-type join-prune command to check whether the number of Join/Prune messages received by downstream interfaces increases.

    • If the number of Join/Prune messages received by downstream interfaces does not increase, run the display pim ipv6 control-message counters interface interface-type interface-number message-type join-prune command on the downstream devices to check whether the downstream devices send Join/Prune messages to upstream devices.
      • If the number of Join/Prune messages increases, the downstream devices send Join/Prune messages. In this case, check whether PIM neighbors can communicate with each other.

      • If the number does not increase, the downstream devices are not working properly. In this case, locate and rectify the faults of the downstream devices.

    • If the number of Join/Prune messages received by downstream interfaces increases, go to step 3.

  3. Check whether IPv6 PIM-SM is enabled on the interface.

    The fault occurs when IPv6 PIM-SM is not enabled on the following interfaces:
    • RPF neighboring interface to the RP

    • RPF interface to RP

    • Interface directly connected to network segment of user hosts (downstream interfaces of the receiver's DR)

    Run the display pim ipv6 interface verbose command on the switch to check IPv6 PIM information on interfaces. Check whether IPv6 PIM-SM is enabled on the preceding interfaces.

    • If "Error: Please enable IPv6 multicast in the system view first." is displayed when you enable IPv6 PIM-SM on interfaces, run the multicast ipv6 routing-enable command in the system view to enable the multicast function. Then, enable IPv6 PIM-SM on the interface.

    • If IPv6 PIM-SM is enabled on all interfaces, go to step 4.

  4. Check whether the RP information is correct.

    Run the display pim ipv6 rp-info command to check whether the switch has learned the RP information that provides services for a multicast group and has the same RP information as other devices that provide services for the same group.

    • If the switch does not have RP information or has different RP information from other devices and the static RP is used in the network,
      • Run the static-rp command to configure the address of the RP that provides services for a multicast group to be the same on all devices.

    • If the RP information that provides services for a multicast group is the same on all devices, go to step 5.

  5. Check whether the RPF route to the RP is available.

    Run the display multicast ipv6 rpf-info ipv6-source-address command on the switch to check whether the RPF route to the RP is available.

    • If the command output does not contain the RPF route to the RP, check the configuration of the unicast route. Run the ping ipv6 command on the switch and on the RP to check whether they can ping each other.

    • If the command output contains the RPF route to the RP:
      • If the command output indicates that the RPF route is a static multicast route, run the display current-configuration command to check whether the static route configuration is correct.

      • If the command output indicates that the RPF route is a unicast route, run the display ipv6 routing-table command to check whether the unicast route is consistent with the RPF route.

    • If the command output contains the RPF route to the RP and the configuration of the route is correct, go to step 6.

  6. Check whether the interface forwarding multicast data is the receiver's DR.

    Run the display pim ipv6 interface interface-type interface-number command to check whether the interface forwarding multicast data is the receiver's DR.

    • If there is no local flag in the command output, the switch is not the receiver' DR. In such a case, you can locate the receiver's DR based on the DR address that is displayed in the command output and go to step 7.

    • If there is local flag in the command output, go to step 7.

  7. Check whether the multicast boundary is configured on the interface.

    Run the display current-configuration interface interface-type interface-number command to check whether the multicast boundary is configured on the interface.

    • If the command output contains "multicast ipv6 boundary", the multicast boundary is configured on the interface. In this case, run the undo multicast ipv6 boundary { ipv6-group-address ipv6-group-mask-length | all | scope } command to delete the multicast boundary configuration or replan the networking to ensure that the multicast boundary is not configured on the RPF interface or the RPF neighbor interface.

    • If the multicast boundary is not configured on the interface, go to step 8.

  8. Check whether the source policy is configured.

    Run the display current-configuration configuration pimv6 command to check current configuration in the PIM-IPv6 view.

    • If the command output contains the "source-policy acl6-number", source-based filtering rules are configured. If the received multicast data does not match ACL rules, the multicast data is discarded. In this case, run the undo source-policy command to delete the configuration or reconfigure the ACL rules to ensure that the multicast data can be forwarded normally.

Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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