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AR Router Troubleshooting Guide

This Product Documentation provides guidance for maintaining AR Enterprise Router, covering common information collection and fault diagnostic commands, typical fault troubleshooting guide, and troubleshooting.
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MSDP Peers Cannot Generate Correct (S, G) Entries

MSDP Peers Cannot Generate Correct (S, G) Entries

Common Causes

This fault is commonly caused by one of the following causes:

  • The MSDP peer to initiate SA messages is not configured on the RP.

  • The logical RP is not configured on the devices to be deployed with anycast RP or configurations of the logical RP are incorrect.

  • MSDP peer relationships are not set up between every two members in a mesh group.

  • The used intra-domain multicast protocol is not PIM-SM.

  • The RPF route to the multicast source is incorrect. For example, the unicast route contains a loop.

  • Configurations are incorrect. For example, the configurations of the SA policy, import policy, TTL, switchover threshold, or multicast boundary are improper.

  • The SA message fails to pass RPF check.

Troubleshooting Flowchart

After configurations are complete on a multicast network, MSDP peers cannot generate correct (S, G) entries.

Figure 20-6 shows the troubleshooting flowchart.

Figure 20-6  Troubleshooting flowchart: MSDP peers cannot generate correct (S, G) entries

Troubleshooting Procedure

Context

NOTE:

Saving the results of each troubleshooting step is recommended. If troubleshooting fails to correct the fault, a record of the actions taken will exist to provide to Huawei technical support personnel.

Procedure

  1. Check that the status of MSDP peers is Up.

    Run the display msdp brief command on the devices setting up an MSDP peer relationship to check whether the status of MSDP peers is Up.

    • If the command output shows that the status of MSDP peers is Down, check whether the MSDP peer interfaces are correctly configured and whether the MSDP peers can ping each other successfully. If the ping fails, perform troubleshooting based on The Ping Operation Fails.

    • If the MSDP peers are both in the Up state, go to Step 2.

  2. Check that SA cache is enabled.

    Run the display current-configuration configuration msdp command on MSDP peers to view the current configurations in the MSDP view.

    • If the command output shows undo cache-sa-enable, SA cache is disabled in the MSDP view. In this case, run the cache-sa-enable command in the MSDP view to enable SA cache.

    • If SA cache has been enabled, go to Step 3.

  3. Check that SA messages have reached MSDP peers.

    Run the display msdp sa-count command on MSDP peers to check the contents of the SA cache.

    • If there is no command output, contact technical support personnel.

    • If the value of the Number of source or Number of group field in the command output is non-zero, SA messages have reached the peers. Then go to Step 4.

  4. Check whether export policies are configured on the MSDP peers.

    Run the display current-configuration configuration msdp command in the MSDP view on the MSDP peers to view the current configurations.

    • If export policies are configured on the MSDP peers, do as follows:
      • If the command output shows the configurations of the peer peer-address sa-policy export command without any parameters, the MSDP peers are disabled from forwarding messages received from the multicast source. Then run the undo peer peer-address sa-policy export command to delete the configurations of export policies.

      • If the command output shows the configurations of the peer peer-address sa-policy export acl advanced-acl-number command with an ACL specified, MSDP peers can forward only the (S, G) entries permitted by the ACL. Then check whether ACL-related commands are run on the MSDP peers and whether (S, G) entries are permitted by the ACL. You can run the undo peer peer-address sa-policy export command to delete the configurations of the ACL or change the configurations of the ACL rules.

    • If no export policies are configured on MSDP peers, go to Step 5.

  5. Check whether import policies are configured on MSDP peers.

    Run the display current-configuration configuration msdp command in the MSDP view on the MSDP peers to view the current configurations.

    • If import policies are configured on MSDP peers, do as follows:
      • If the command output shows the configurations of the peer peer-address sa-policy import command without any parameters, the MSDP peers are disabled from receiving messages from the multicast source. Run the undo peer peer-address sa-policy import command to delete the export policy configurations.

      • If the command output shows the configurations of the peer peer-address sa-policy import acl advanced-acl-number command with an ACL specified, MSDP peers can receive only the (S, G) entries permitted by the ACL. Check whether ACL-related commands are run on the MSDP peers and whether (S, G) entries are permitted by the ACL. Run the undo peer peer-address sa-policy import command to delete the configurations of the ACL or change the configurations of the ACL rule.

    • If no import policies are configured on the MSDP peers, go to Step 6.

  6. Check whether the current MSDP peer receives multicast data from the multicast source.
    • If the current MSDP peer does not receive multicast data from the multicast source, troubleshoot the upstream device following the preceding steps.

    • If the current MSDP peer receives multicast data from the multicast source, go to Step 7.

  7. Check whether the current MSDP peer is an RP.

    Run the display pim routing-table command on the MSDP peer closest to the multicast source to view the routing table.

    • If the (S, G) entry does not have a 2MSDP flag, the MSDP peer is not an RP. Change the configurations of the RP or MSDP peer on the PIM-SM network to ensure that the MSDP peer is an RP.

    • If the MSDP peer is an RP, go to Step 8.

  8. Check whether import-source policies are configured on the current MSDP peer.

    The import-source [ acl acl-number ] command is used to enable an MSDP peer to filter the (S, G) entries to be advertised based on source addresses when creating SA messages. The MSDP peer can control the transmission of multicast source information. By default, SA messages can be used to advertise information about all known multicast sources.

    Run the display current-configuration configuration msdp command in the MSDP view on the MSDP peer closest to the multicast source to view the current configurations.

    • If import-source policies are configured on the MSDP peer, do as follows:
      • If the command output shows the configurations of the import-source command without any parameters, the MSDP peer is disabled from advertising multicast source information. Then run the undo import-source command to delete the import-source policy configurations.

      • If the command output shows the import-source acl acl-number command with an ACL specified, the MSDP peer advertises only (S, G) information matching the ACL. Then check whether ACL-related commands are run on the MSDP peer and whether (S, G) entries are permitted by the ACL. Then run the undo import-source command to delete the configurations of the ACL or change the configurations of the ACL rule.

    • If no import policies are configured on the MSDP peers, go to Step 9.

  9. If the fault persists, collect the following information and contact technical support personnel.

    • Results of the preceding operation procedure
    • Configuration files, log files, and alarm files of the device

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Updated: 2019-05-10

Document ID: EDOC1000079719

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