This Article Applies to:

 

All Omada smart, L2+, and L3 switches.

 

Issue Description:

 

1. Network device configuration issue: It may be that network devices (such as routers, switches) are not properly configured to support multicast data packet transmission. If network devices do not enable multicast functionality or are configured incorrectly, multicast data packets may not be transmitted correctly.
2. Host configuration issue: It may be that the host's network settings are not properly configured to support multicast. If the host does not configure the network interface correctly to receive multicast data packets, or if the firewall blocks the transmission of multicast data packets, multicast may not work.
3. Group address conflict: There may be multiple devices in the network using the same multicast group address, which can cause packet confusion or prevent packets from being routed correctly to the target receivers, resulting in multicast not working.
4. Incorrect TTL setting: If the TTL (Time-to-Live) setting of the data packets is too low, it may cause the packets to be dropped during transmission and not reach the target receivers, resulting in multicast not working.
5. Network topology issues: Complex network topology or network faults can affect the transmission of multicast data packets, causing data to not reach the target receivers correctly and resulting in multicast not working.

 

Troubleshooting:

 

1. Check loops and ports.

 

Check the state of the physical port and STP. Go to Devices, select the target switch to open the Properties window, and check if the port is linked up normally and if the port is in the STP Blocking state.

 

 

If the port is not linked up, change the network cable and try again, or try another available port on the switch.

If the port is in the STP Blocking state, eliminate network loops first.

 

2. Check the multicast member ports.

 

Check the state of multicast member ports. Go to Tools > Terminal, select Switch for Device Type, choose the target switch in the pop-up window of Sources and click Confirm. Click Open Terminal.

First enter enable in the Terminal, and then enter show ip igmp snooping groups vlan vlan-id to check if the Switch ports in the multicast group correspond to the user-side ports.

 

 

1. If the Switch ports correspond to the user-side ports, it indicates that the switch has received the IGMP Report requests from the user-side devices.

2. If the Switch ports do not correspond to the user-side ports correctly, the following are the possible causes, which may require packet capture for further diagnosis.

• The switch does not receive the Report message from the user or the message format does not meet the device’s requirements.
• The IGMP messages received by the switch do not conform to the IGMP standards. The destination MAC or IP address is not a multicast address.
• The version of the IGMP messages received by the switch is not compatible with the version configured on the device.

 

3. Check the router port

 

Enter show ip igmp snooping vlan vlan-id to check if the router port exists.

 

1. If the router port exists, it indicates that the uplink port has received the IGMP Query messages from the upstream querier, or that the static router port has sent the Query messages.
2. If the router port does not exist, it means that no static router port has been configured, and that the switch has not received any IGMP Query messages from the upstream layer 3 device. In this case, you need to debug and troubleshoot the upstream device.

 

4. Check the multicast packets.

Enter show ip igmp snooping interface packet-stat to check the multicast packets received by the switch.

 

1. Check if the switch is receiving any Error messages. If so, you need to capture the packets on the corresponding port for further analysis.
2. Check the IGMP Report message counters on the member ports. If the Report message counters do not increase after a member port receives an IGMP Report request, it indicates that the port is not receiving the Report messages.
3. Check the IGMP Query message counters on the router port. If the Query message counters do not increase, it indicates that the port is not receiving the IGMP Query messages from the upstream device or the static router port.

 

5. Collect information and seek technical support.

If the previous steps have not been able to resolve the issue, please collect the relevant information from the previous steps, and then seek the support team.

 

Note:

 

1. What is STP/RSTP?

STP (Spanning Tree Protocol) and RSTP (Rapid Spanning Tree Protocol) are two network protocols designed to prevent loop issues in Local Area Networks (LANs). STP, the earlier standard defined by IEEE 802.1D, prevents loops by building a loop-free network topology. RSTP, an enhancement over STP, is defined by IEEE 802.1w and offers faster network recovery times.
These protocols are primarily used in Ethernet networks to ensure that data packets do not loop indefinitely within the network, thus avoiding network congestion and failures.

https://en.wikipedia.org/wiki/Spanning_Tree_Protocol

https://en.wikipedia.org/wiki/Multiple_Spanning_Tree_Protocol

 

Update Log:

 

Aug 23rd, 2024:

Release of this article.

 

Recommended Threads:

 

Troubleshooting Techniques for Laymen

How to Upgrade/Downgrade Omada Switches

Common Questions About the Hardware Version and Firmware Update

 

Feedback:

 

• If this was helpful, welcome to give us Kudos by clicking the upward triangle below.
• If there is anything unclear in this solution post, please feel free to comment below.
• If you encounter such an issue, please follow the troubleshooting above to check your settings. Besides, ensure your Omada Controller and Switch are running with the latest firmware.
• If the issue still exists after you try the suggestion above, please feel free to comment below or contact our support team with a detailed description of your issue and the steps you have tried.

 

Thank you in advance for your valuable feedback!

 

------------------------------------------------------------------------------------------------

Have other off-topic issues to report? 

Welcome to > Start a New Thread < and elaborate on the issue for assistance.