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SG3210x-MP LAGG with LACP and not getting DHCP

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SG3210x-MP LAGG with LACP and not getting DHCP

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SG3210x-MP LAGG with LACP and not getting DHCP
SG3210x-MP LAGG with LACP and not getting DHCP
2025-01-07 01:31:10 - last edited 2025-01-07 15:00:34
Tags: #Configuration #LAG
Model: TL-SG3210XHP-M2  
Hardware Version: V1
Firmware Version: 1.2

Hi.

 

New to this forum and using my first TP-Link device. It is the SG3210X-MP switch. I have used a bit of Netgear, but mainly use Cisco SG2xx/3xx and CBS250/350 managed switches.

 

The part that I have having trouble with is LAGG with LACP. I have tried both active and passive modes. If both ports are not active (connected) it does not work. Why is this?

 

I do the same on my Cisco switches and can only have one connection of the LAGG connected and it all works fine. I found this out by playing with the trunk LAGG. I do not have another system free to test the regular LAGG with LACP to test. 

 

Removing the LAGG and just having regular ports, all is fine.

 

Thanks.

 

Andy

 

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Re:SG3210x-MP LAGG with LACP and not getting DHCP-Solution
2025-01-07 01:49:24 - last edited 2025-01-07 15:00:34

Hi @j140 

Thanks for posting in our business forum.

Active mode can be used at the same time between TP-Link switches. At least during the test we have done, it works.

Based on your description, are you using the switch with a different brand? That might be a problem if they are both in active mode.

 

Generally, for a LACP, it is one side active, one side passive. This is the RFC and what the industry recommends.

 

For the reason why, I cannot comment. I think this should be explained if you do a Wireshark and follow the definition of the LACP from RFC. Find out the irregular values and that might be self-explained.

 

Static LAG would work with most brands. No issues.

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Re:SG3210x-MP LAGG with LACP and not getting DHCP-Solution
2025-01-07 01:49:24 - last edited 2025-01-07 15:00:34

Hi @j140 

Thanks for posting in our business forum.

Active mode can be used at the same time between TP-Link switches. At least during the test we have done, it works.

Based on your description, are you using the switch with a different brand? That might be a problem if they are both in active mode.

 

Generally, for a LACP, it is one side active, one side passive. This is the RFC and what the industry recommends.

 

For the reason why, I cannot comment. I think this should be explained if you do a Wireshark and follow the definition of the LACP from RFC. Find out the irregular values and that might be self-explained.

 

Static LAG would work with most brands. No issues.

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Re:SG3210x-MP LAGG with LACP and not getting DHCP
2025-01-07 03:25:54

  Hi @Clive_A. Thanks for the reply.

 

I think I tried that as well but, will try again and let you know.

 

Andy

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Re:SG3210x-MP LAGG with LACP and not getting DHCP
2025-01-07 15:13:30

  Hi @Clive_A 

 

After a bit more tweaking, it is working. After changing over to Static LAG as you suggested, it was working but, only on odd number ports when I had both LAG feed ports connected. If, I unplugged either of the LAGG ports, it was working.

 

I checked carefully my setup on the Cisco switch. At some point with testing different things and my butter fingers, I had one of the ports set to PVID 27 instead of 1. Fixed that and it is working.

 

I was checking LLPD info on the Cisco switches and could see that there was communications.

 

On a different note. I was seeing missing heartbeats every so often out of the blue and even disconnections from the omada controller software. I had to close down and open up a new session. Will keep an eye out for that over the next few days. If it keeps acting up, will revert to configuring from the web gui of the unit.

 

Thanks again for your help and the fix.

 

Andy

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