Contents

Troubleshooting multicast 1

MVPN issues· 1

Default MDT establishment failure· 1

Multicast routing table incorrectly built for a VPN instance· 3

Troubleshooting multicast

MVPN issues

Default MDT establishment failure

Symptom

The PEs cannot establish a default MDT or establish PIM neighbor relationships in the same VPN.

Common causes

The following are the common causes of this type of issue:

·     Incorrect MTI configuration. To establish a default MDT in a VPN instance, you must specify a default group and an MVPN source interface with a valid IP address for the MTI for that VPN instance on each PE.

·     Incorrect default group configuration. You must specify the same default group for the same VPN instance across PEs. A default group uniquely identifies a default MDT. The PEs cannot establish a default MDT for a VPN instance if they have different default groups for that VPN instance.

·     Incorrect PIM configuration. To correctly establish a default MDT for a VPN instance, you must enable the same PIM mode on all interfaces in that VPN instance across PEs and all interfaces on the P devices. PIM mode consistency ensures establishment of PIM neighbor relationships between PEs in the same VPN instance for a successful default MDT establishment.

·     Absence of unicast routes or BGP peers. PIM can only obtain routing information correctly if both unicast routes and BGP peers are configured.
PIM disabled on the MTI for the VPN instance. This prevents PEs from establishing PIM neighbor relationships in the same VPN instance. To enable PIM on the MTI for a VPN instance, you must enable PIM on a minimum of one interface in the VPN instance.

Troubleshooting flow

Figure 1 shows the troubleshooting flowchart.

Figure 1 Flowchart for troubleshooting the default MDT establishment failure

Solution

1.     Execute the display interface command to check the state and address encapsulation information of MTIs.

2.     Execute the display multicast-vpn default-group command to verify that different PEs have the same default group for the same VPN instance.

3.     Execute the display pim interface verbose command on each device. Verify that PIM is enabled on a minimum of one interface in the VPN instance on each PE. Ensure that the same PIM mode is enabled on the interfaces in the same VPN instance across PEs and all interfaces on the P devices.

4.     Execute the display ip routing-table command to verify that the local PE has unicast route entries to the the remote PE in the same VPN instance.

5.     Execute the display bgp peer command to verify that a BGP peer relationship has been established between the PEs.

6.     If the issue persists, collect the following information and contact Technical Support:

¡     Results of each step.

¡     The configuration file, log messages, and alarm messages.

Multicast routing table incorrectly built for a VPN instance

Symptom

The device cannot correctly build a multicast routing table for a VPN instance.

Common causes

The following are the common causes of this type of issue:

·     The VPN instance or public instance does not have bootstrap router (BSR) information. To build a multicast routing table correctly for a VPN instance enabled with PIM-SM, both the VPN instance and the public instance must have the BSR information for that VPN instance.

·     The VPN instance or public instance lacks RP information. To build a multicast routing table correctly for a VPN instance enabled with PIM-SM, both the VPN instance and the public instance must have the RP information for the VPN instance and routes to that RP. In addition, the devices in the public instance and VPN instance must correctly establish PIM neighbor relationships.

·     No active routes are available between the DRs and the RP for the private network. You must make the DRs in the private network have routes to their RP, and the VPN instance for the private network has routes to the multicast source.

Troubleshooting flow

Figure 1 shows the troubleshooting flowchart.

Figure 2 Troubleshooting flowchart for issues with building the multicast routing table for a VPN instance

Solution

1.     Use the display pim bsr-info command to verify that the public and VPN instances have BSR information. If BSR information is absent, check for unicast routes to the BSR.

2.     Use the display pim rp-info command to verify that the RP information is correct. If no RP information is displayed, verify the presence of a unicast route to the RP. Additionally, execute the display pim neighbor command to verify that PIM neighbor relationships have been correctly established on both public and private networks.

3.     Use the ping command to check connectivity between the DR and RP on the private network, and between the receivers and the multicast source.

4.     If the issue persists, collect the following information and contact Technical Support:

¡     Results of each step.

¡     The configuration file, log messages, and alarm messages.