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LAG + 2nd switch causing network loops

LAG + 2nd switch causing network loops

LAG + 2nd switch causing network loops
LAG + 2nd switch causing network loops
3 weeks ago
Tags: #Network Connectivity #Link Aggregation
Model: Archer AX73  
Hardware Version: V1
Firmware Version: 1.3.6 Build 20240407 rel.43274(4555)

Hello,

 

I have a AX73 router with static LAG configured (2 ports). The switch connected to it, TL-SG108E also has LAG configured on the interface.

 

I connected a 2nd switch to the router (TL-SG605E) and my first switch started flashing amber and green light on the two ports that receive the cable from the router, indicating a network loop.

 

If I disconnect the 2nd switch from the router, everything goes back to normal.

 

If I remove the LAG configuration from both the router and the 1st switch and connect the 2nd switch everything works as normal.

 

What do you think the problem might be? Obviously it is related with the LAG but I just can't figure it out.

 

All 3 devices have updated firmware.

 

It would be nice to be able to use the LAG feature in order to have not just redundancy bit also increased bandwidth.

 

Any help? For reference, on the sw I had it on LAG 2, ports 7 and 8.

 

 

 

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#1
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4 Reply
Re:LAG + 2nd switch causing network loops
3 weeks ago

  @danoffline 

Hi,

 

The issue involves a network loop created when LAG is set up between an AX73 router and a TL-SG108E switch, then extended to a second TL-SG605E switch. The loop results in abnormal port indicator behaviour. Solutions include ensuring consistent LAG settings across devices, checking for STP to prevent loops, and verifying configurations. 

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#2
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Re:LAG + 2nd switch causing network loops
3 weeks ago

  @Sunshine 

Hi there. The 2nd sw is connect directly to the AX73, as is the 1st one. 

 

How do I configure STP? I didn't see on the GUI of the sw's

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#3
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Re:LAG + 2nd switch causing network loops
3 weeks ago

  @Sunshine I did all of that. 

So, the only think I can think of is that the LAG is not working? Firmware issue? 

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#4
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Re:LAG + 2nd switch causing network loops
3 weeks ago

@danoffline 

 

Can you provide a detailed network layout showing how the AX73, SG108E, and SG105E are connected? Based on your description, only after connecting the 2nd switch, which I assume is SG105E, does the SG108E indicate a network loop.

 

Where is the SG105E connected on the AX73? Please make sure it is not connected to the SG108E through another port.

 

The LAG settings on both the AX73 and SG108E are quite simple, so I assume there are no issues there with the settings. However, please check the Ethernet cabling to ensure everything is correctly connected to avoid a network loop.

 

BTW, neither the SG108E nor the SG105E supports STP.

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#5
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