TL-SG108PE 5.0 sends back IGMP Packets if VLAN is used on only one Port

TL-SG108PE 5.0 sends back IGMP Packets if VLAN is used on only one Port

TL-SG108PE 5.0 sends back IGMP Packets if VLAN is used on only one Port
TL-SG108PE 5.0 sends back IGMP Packets if VLAN is used on only one Port
2024-06-28 10:00:01 - last edited 2024-07-01 03:43:29

Hi,
i think I found a bug.

 

I have an uplink port with some tagged VLANs but don't assign one of the VLANs to another port. (VLAN 1000 is only used tagged on port 8, nowhere else)
When a PC in this VLAN broadcasts a IGMP membership query, the switch returns that packet on the same port and VLAN.
Because the source MAC is the one of the PC, another switch will change it's MAC table and think the PC is on another port now.
Therefor the PC is not reachable anymore until it sends some new packets.

 

One of the following steps will stop the switch from returning the IGMP packets:
1. Disable IGMP Snooping
2. Assign VLAN 1000 to an additional port (tagged or untagged)

 

I could reproduce this behavior with a single PC and the TL-SG108PE by sending IGMP packets manually and sniffing with wireshark. The packets were duplicated by the switch.

The switch should never send a packet with a source MAC that's not reachable in it's path.

 

TL-SG108PE v5.0
Firmware: 1.0.0 Build 20230218 Rel.51358

 

I hope this issue can be resolved in a firmware update.
Can take some time to find this problem in your network.

 

guni
 

e21abb1e27024250986770f21e619086

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Re:TL-SG108PE 5.0 sends back IGMP Packets if VLAN is used on only one Port
2024-07-01 02:36:42 - last edited 2024-07-01 03:43:29

 Hi @guni 

 

Thank you for your valuable feedback. 

 

I will forward the issue to our D&R department. 

 

A solution may not be available very soon. If the issue is urgent for you, we suggest to replace the model to an Omada managed switch. 

guni wrote

Hi,
i think I found a bug.

 

I have an uplink port with some tagged VLANs but don't assign one of the VLANs to another port. (VLAN 1000 is only used tagged on port 8, nowhere else)
When a PC in this VLAN broadcasts a IGMP membership query, the switch returns that packet on the same port and VLAN.
Because the source MAC is the one of the PC, another switch will change it's MAC table and think the PC is on another port now.
Therefor the PC is not reachable anymore until it sends some new packets.

 

One of the following steps will stop the switch from returning the IGMP packets:
1. Disable IGMP Snooping
2. Assign VLAN 1000 to an additional port (tagged or untagged)

 

I could reproduce this behavior with a single PC and the TL-SG108PE by sending IGMP packets manually and sniffing with wireshark. The packets were duplicated by the switch.

The switch should never send a packet with a source MAC that's not reachable in it's path.

 

TL-SG108PE v5.0
Firmware: 1.0.0 Build 20230218 Rel.51358

 

I hope this issue can be resolved in a firmware update.
Can take some time to find this problem in your network.

 

guni
 

e21abb1e27024250986770f21e619086

 

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