This article explains how to troubleshoot Multicast issues with the EX device configured as a Layer 2 switch.
For configuration information or if your EX device is configured as a Layer 3 switch, refer to KB21990-Resolution Guides and Articles - Junos OS - Troubleshoot Multicast.
Perform the following steps to troubleshoot a Multicast issue with EX Series Ethernet switches configured as a Layer 2 switch:
Note: For the flowchart version of these steps, click the flowchart icon: |
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Map out your Network Topology and identify the following. For an example with definitions, refer to KB21591 - Sample Multicast Network Topology with Junos OS devices.
- Multicast Client (Receiver) and the EX port to which it is connected
- Multicast Server (Source) and the EX port to which it is connected
- Multicast Group (the group address not working)
- VLANs on the ports of the EX switch
Confirm that Unicast traffic connectivity is working between the Multicast Client (receiver) and Server (source).
- Unicast traffic must be working before continuing to troubleshoot Multicast.
- One way is to test Unicast traffic is to ping from the Multicast client to the Multicast server. (Check if ping is permitted on the devices.)
- If the ping response fails between the Multicast client and server, then narrow down the issue to the immediate next-hop connected device to test if Unicast routing is working.
- Similarly from the upstream neighboring devices, follow the above step along the path taken by each next-hop device to reach the server.
Do you have Unicast connectivity working between the Multicast Client and Server?
- Yes - Jump to Step 4
- No - Continue to Step 3
Ping from the EX switch to the Multicast Server. Do you have Unicast connectivity working between the EX switch and the Multicast Server?
- Yes - Continue to Step 4
- No - Troubleshoot environment for Unicast connectivity. Unicast traffic must be working before continuing to troubleshoot Multicast.
Confirm that the EX switch is receiving Multicast traffic (stream) sent by the Multicast Server to the Client.
- To do this, create a Firewall Filter specifying the destination-address of the Multicast Server group address. For an example of how to do this, refer to KB21589 - Firewall Filter Examples to verify Multicast traffic is reaching the EX switch.
- Apply the Firewall Filter on the EX switch interface to the ingress interface where the Multicast Server stream is expected.
- Check if the Firewall Filter counters increment. This helps to understand if the traffic sent by the Multicast server is being received by the EX switch or not.
Is the EX switch receiving traffic (stream) from the Multicast Server (source), that is, is the Firewall Filter counter incrementing?
- Yes - Continue to Step 5
- No - If there is no traffic from the Multicast server (source) identified on the EX interface, narrow down the issue towards the Multicast source and the path, traversing each next-hop device reaching the source.
On the EX switch, is igmp-snooping
enabled on the VLAN in which the Multicast Client and Server are connected? (It is enabled by default.) For more information about igmp-snooping
, refer to KB21735 - Verify Multicast client is listed in IGMP Snooping Database.
-
To check, run the configuration command: show protocols
The following output shows that igmp-snooping
is enabled for all the VLANs of the EX device. It can also be enabled on a specific VLAN.
root@Juniper-L2_EX# show protocols
igmp-snooping {
vlan all;
- Yes -
igmp-snooping
is enabled - Continue to Step 6
- No - Packets are flooded to all the ports when
igmp-snooping
is not enabled. Configure port mirroring to see if Multicast stream is being forwarded by the switch. For more information about port mirroring, refer to Understanding Port Mirroring on EX Series Switches. Continue to Step 9, if still not resolved.
On the EX switch, is the Multicast Receiver (client) in question listed in the IGMP snooping table? For more information and an example of how to do this, refer to KB21735 - Verify Multicast client is listed in IGMP Snooping Database.
- No - Continue to Step 7
- Yes - Jump to Step 9
Confirm that the EX switch is receiving IGMP reports from the Multicast Client.
- To do this, create a Firewall Filter specifying the source-address of the Multicast client and the destination-address of the Multicast Server Group address. For more information and an example of how to do this, refer to KB21589 - Firewall Filter Examples to verify Multicast traffic is reaching the EX switch.
- Apply the Firewall Filter to the EX switch interface connected to the Multicast client (receiver).
- Check if the Firewall Filter counters are incrementing; this confirms that the EX switch is receiving the client's IGMP reports.
Is the EX switch receiving IGMP reports from the Multicast Client?
- No - Continue to Step 8
- Yes - Jump to Step 9 and open a case
Are the Multicast clients configured to send IGMP reports?
Note: Not all clients are intentionally configured to send IGMP reports.
If the above steps do not resolve the problem, then collect the following and open a case with your technical support representative:
- Network Topology
- Multicast Client (Receiver) and the EX port to which it is connected
- Multicast Server (Source) and the EX port to which it is connected
- Multicast Group (the group address not working)
- VLANs on the ports of the EX switch
-
IGMP Snooping logs and data: (only if Clients are configured to send IGMP Reports)
root@Juniper-L2_EX# set protocols igmp-snooping traceoptions file igmp-snooping-reports.log
root@Juniper-L2_EX# set protocols igmp-snooping traceoptions file size 1m
root@Juniper-L2_EX# set protocols igmp-snooping traceoptions flag all
root@Juniper-L2_EX# run clear igmp-snooping membership
root@Juniper-L2_EX# run clear igmp-snooping statistics
[wait for next report...approx 120 seconds]
root@Juniper-L2_EX# run show igmp-snooping membership detail
root@Juniper-L2_EX# run show igmp-snooping membership vlan <vlan name> detail
root@Juniper-L2_EX# run show igmp-snooping statistics
-
Collect all the logs on the EX device using the 'file archive' command. For instructions, refer to KB20569 - Collecting Logs from EX series devices using the 'file archive' command.
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Request Support Information:
root@Juniper-L2_EX# run request support information all-members | no-more
2020-05-06: Updated all links and verified the remaining content, all are active and valid; added port mirroring information link for reference