TL-SG1005LP appears to block/consume IGMPv2 packets

TL-SG1005LP appears to block/consume IGMPv2 packets

TL-SG1005LP appears to block/consume IGMPv2 packets
TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-09 07:44:59 - last edited 2024-08-14 07:23:30
Tags: #IGMP
Model: TL-SG1005LP  
Hardware Version: V2
Firmware Version: Unknown

Hi,

 

I'm developing a consumer device based on a ST micro with lwIP as the TCP/IP stack. One requirement - based on interoperation with existing products - is to respond to multicast UDP packets that are used as a form of device discovery. To make routers forward the UDP packets I need to use IGMP to join the relevant group. This is trivial and seems to work well. The lwIP stack uses IGMPv2.

 

The problems start when I connect my board to an unmanaged TP-Link switch (TL-SG1005LP) in my office and access the network that way. I've used Wireshark to monitor the traffic during the 'join group' phase and have observed as below:-

  • When the device and PC are connected directly through the main router, the IGMPv2 messages appear on Wireshark and multicast packets are received at the device.
  • When the device is connected through the switch, the IGMPv2 packets are not seen in Wireshark and multicast packets are not received.

 

The only conclusion I can draw is that the switch is either filtering or consuming the IGMPv2 packets.

 

I have other devices that use the same mechanism but with IGMPv3 packets - interestingly these always get through.

 

Questions:-

  • Is this expected behaviour or a bug? If expected - why? If a bug - is there a fix?
  • As the switch is unmanaged, can I configure it to not drop these packets?
  • Is this the same across other TP-Link devices?
  • Do other manufacturers' switches have this issue? What switch do I need that will not do this? 

 

Thanks for any assistance.

 

Chris

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#1
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1 Accepted Solution
Re:TL-SG1005LP appears to block/consume IGMPv2 packets-Solution
2024-08-14 07:12:22 - last edited 2024-08-14 07:23:30

  @Clive_A Thanks for the continued support.

 

FYI I have just purchased and tested the same setup with a SG2210MP and this behaves correctly straight out of the box; the IGMPv2 Join Group message is propagated around the network and the appropriate multicast traffic is then correctly delivered to my device.

 

I'm going to move on with my work rather than spend any more time trying to use the SG1005, but I maintain that this is blocking the IGMPv2 traffic and therefore not working correctly.

 

Thanks and regards,

Chris

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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-11 04:59:15 - last edited 2024-08-11 04:59:24

Hi  @CShaw 

CShaw wrote

 

Questions:-

  • Is this expected behaviour or a bug? If expected - why? If a bug - is there a fix?
  • As the switch is unmanaged, can I configure it to not drop these packets?
  • Is this the same across other TP-Link devices?
  • Do other manufacturers' switches have this issue? What switch do I need that will not do this? 

 

Thanks for any assistance.

 

Chris

1) It is an unmanaged switch, which means there will never be a firmware release/fix.

2) Unfortunately, no.

3) For smart switch you can drop the unknown packets. This is an option you can choose. See the User Guide of the smart switch. Refer to the model naming format guide I wrote.

4) I am not aware of/familiar with any other vendors.

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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-11 23:48:32 - last edited 2024-08-12 00:06:14

  @Clive_A Thanks for the reply.

 

Can you also please confirm the operation as described, and whether this is a known/accepted bug.

 

Are you able to guarantee that if I purchase an EasySmart switch (e.g. TL-SG1210MPE or any other with an 'E' suffix) this will not also have this fault?

 

Thanks,

 

Chris

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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-12 01:34:07

Hi @CShaw 

Thanks for posting in our business forum.

CShaw wrote

  @Clive_A Thanks for the reply.

 

Can you also please confirm the operation as described, and whether this is a known/accepted bug.

 

Are you able to guarantee that if I purchase an EasySmart switch (e.g. TL-SG1210MPE or any other with an 'E' suffix) this will not also have this fault?

 

Thanks,

 

Chris

Smart switch is starting with the 2000 series. Not 1000 series.

Best Regards! If you are new to the forum, please read: Howto - A Guide to Use Forum Effectively. Read Before You Post. Look for a model? Search your model NOW Official and Beta firmware. NEW features! Subscribe for the latest update!Download Beta Here☚ ☛ ★ Configuration Guide ★ ☚ ☛ ★ Knowledge Base ★ ☚ ☛ ★ Troubleshooting ★ ☚ ● Be kind and nice. ● Stay on the topic. ● Post details. ● Search first. ● Please don't take it for granted. ● No email confidentiality should be violated. ● S/N, MAC, and your true public IP should be mosaiced.
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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-12 02:13:11

  @Clive_A Thank you for clarifying, so understand I need to look at the SMB switches rather than home office.

 

  1. Can you please confirm the operation of the SG1005LP has the fault as described above, and whether this is a known/accepted bug?
  2. Can you confirm that any of the smart switches (2000 series), in particular models SG2218P, SG2016P, SG2210P and SG2210MP, will NOT have the fault?

 

Thanks,

 

Chris

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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-12 02:48:06

Hi @CShaw 

Thanks for posting in our business forum.

CShaw wrote

  @Clive_A Thank you for clarifying, so understand I need to look at the SMB switches rather than home office.

 

  1. Can you please confirm the operation of the SG1005LP has the fault as described above, and whether this is a known/accepted bug?
  2. Can you confirm that any of the smart switches (2000 series), in particular models SG2218P, SG2016P, SG2210P and SG2210MP, will NOT have the fault?

 

Thanks,

 

Chris

I cannot reply to them before I have a test result from the dev. The specific reason for why that happens to your network is unknown to me.

We will do some generic multicast test to see if this is a problem.

Best Regards! If you are new to the forum, please read: Howto - A Guide to Use Forum Effectively. Read Before You Post. Look for a model? Search your model NOW Official and Beta firmware. NEW features! Subscribe for the latest update!Download Beta Here☚ ☛ ★ Configuration Guide ★ ☚ ☛ ★ Knowledge Base ★ ☚ ☛ ★ Troubleshooting ★ ☚ ● Be kind and nice. ● Stay on the topic. ● Post details. ● Search first. ● Please don't take it for granted. ● No email confidentiality should be violated. ● S/N, MAC, and your true public IP should be mosaiced.
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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-12 02:50:00

  @Clive_A Thank you very much.

 

Regards,

Chris

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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-12 06:54:00

Hi @CShaw 

Thanks for posting in our business forum.

CShaw wrote

  @Clive_A Thank you very much.

 

Regards,

Chris

Based on the team's reply, when there is a router involved, an IGMP report will be sent to the router.

Will you capture this on the router? Is the query frame sent to the switch?

Best Regards! If you are new to the forum, please read: Howto - A Guide to Use Forum Effectively. Read Before You Post. Look for a model? Search your model NOW Official and Beta firmware. NEW features! Subscribe for the latest update!Download Beta Here☚ ☛ ★ Configuration Guide ★ ☚ ☛ ★ Knowledge Base ★ ☚ ☛ ★ Troubleshooting ★ ☚ ● Be kind and nice. ● Stay on the topic. ● Post details. ● Search first. ● Please don't take it for granted. ● No email confidentiality should be violated. ● S/N, MAC, and your true public IP should be mosaiced.
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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-13 00:55:42

  @Clive_A Thanks for the follow-up.

 

The router (in this case, a TP-Link AX-1800) sends IGMPv3 membership queries every 255s or so. I can see IGMPv3 replies from several devices at this point, but not from my IGMPv2-generating device. This is the same whether I use Wireshark whilst connected to the wi-fi or to the switch. My laptop is subscribed to the mutlicast group 239.192.0.1 that we use.

As soon as I remove the switch from the topology the IGMPv2 message is visible across the network and the multicast works.

I've tried to capture the topology below. GGB-i1 is our development device. The WAP is a TP-Link WA850RE - i.e. all network infrastructure is TP-Link.

 

The two Wireshark captures below show the problem. My device IP is 192.168.1.106. In the first you can see the IGMPv2 Join Group messages. The switch is not present in this case.

In the second, the same test has been run with the switch in place. There is no IGMP traffic from the device as it has been blocked/consumed by the switch. 

 

The main difference in v2 and v3 is the destination of the message: always 224.0.0.22 in v3, but the mutlicast address in v2.

 

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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-14 01:12:55

Hi @CShaw 

Thanks for posting in our business forum.

CShaw wrote

  @Clive_A Thanks for the follow-up.

 

The router (in this case, a TP-Link AX-1800) sends IGMPv3 membership queries every 255s or so. I can see IGMPv3 replies from several devices at this point, but not from my IGMPv2-generating device. This is the same whether I use Wireshark whilst connected to the wi-fi or to the switch. My laptop is subscribed to the mutlicast group 239.192.0.1 that we use.

As soon as I remove the switch from the topology the IGMPv2 message is visible across the network and the multicast works.

I've tried to capture the topology below. GGB-i1 is our development device. The WAP is a TP-Link WA850RE - i.e. all network infrastructure is TP-Link.

 

 

The two Wireshark captures below show the problem. My device IP is 192.168.1.106. In the first you can see the IGMPv2 Join Group messages. The switch is not present in this case.

 

In the second, the same test has been run with the switch in place. There is no IGMP traffic from the device as it has been blocked/consumed by the switch. 

 

The main difference in v2 and v3 is the destination of the message: always 224.0.0.22 in v3, but the mutlicast address in v2.

 

 

I asked the test team to look into this.

So, the PC that is used by Wireshark may not be included in the multicast group so it does not receive anything. This case might be the described situation.

Well, the switch cannot be configured, you cannot know this port mirror.

 

You can try out the models that do not support IGMP like LS1005G. Or models that can disable the IGMP snooping.

It does not support V3 and it is normal that it does not process V3 traffic.

Best Regards! If you are new to the forum, please read: Howto - A Guide to Use Forum Effectively. Read Before You Post. Look for a model? Search your model NOW Official and Beta firmware. NEW features! Subscribe for the latest update!Download Beta Here☚ ☛ ★ Configuration Guide ★ ☚ ☛ ★ Knowledge Base ★ ☚ ☛ ★ Troubleshooting ★ ☚ ● Be kind and nice. ● Stay on the topic. ● Post details. ● Search first. ● Please don't take it for granted. ● No email confidentiality should be violated. ● S/N, MAC, and your true public IP should be mosaiced.
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Re:TL-SG1005LP appears to block/consume IGMPv2 packets
2024-08-14 01:37:00

  @Clive_A Thanks for continuing to look into this, your help is much appreciated.

 

The PC is in the mutlicast group - I have used the `socat` utility to ensure it is joined. I have disabled IGMP snooping on the wireless router and this is why the IGMPv2 packets are seen in the first instance.

 

It would be helpful if you were able to try and reproduce this, but I understand this may not be possible. I can't really 'try out' different models without purchasing, so this isn't really possible. 

 

I'll weigh up whether to buy a SG2210MP instead - if this may work - or to get a Cisco unit.

 

Regards,

Chris

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