Hi  @Clive_A 

Both switches are already running the latest available firmware.

I see packet loss in ping test but also in VOIP(SIP) and other applications

I will do as you suggest and see what happens if I reduce the number of ports in the LAG and report back.

Many thanks

Kind regards

John

Hi @johndpar,

I currently have a T1600G-28TS lagged (2 RJ45 ports) to a SG3428X using LACP.  It's active on the SG3428; my T1600G donesn't have an active/passive option, but it works w/o any issues.  I've had issues in other setups in the past were the pre-lagged port config caused issues.  Try removing the lag, set the member ports back to the basic default configuration and then recreate the lag.  Also, have you tried using 4 non-SFP ports.  Based on your configuration, I assume your SFP ports are loaded with RJ45 transceivers so there could heat, power or transceiver problem.

  @D-C 

Thank you for your suggestions.

Yes the SFP ports are loaded with 1G RJ45 modules - https://www.amazon.co.uk/dp/B0D12MH292/ref=pe_27063361_485629781_TE_item_image

Somewhat lower cost than the TL-SM331T but same spec.

I thought the problem had resolved itself after I unplugged and plugged the 4 modules, but after a couple of days the problem returned.

I've enabled remote syslog and that shows what is happening:

Dec 30 16:55:18 SG3210XHP-M2 53450 Tw1/0/5 changed state to down.
Dec 30 16:55:20 SG3210XHP-M2 53449 Tw1/0/5 changed state to up.
Dec 30 16:55:33 SG3210XHP-M2 53450 Tw1/0/6 changed state to down.
Dec 30 16:55:35 SG3210XHP-M2 53449 Tw1/0/6 changed state to up.
Dec 30 16:55:38 SG3210XHP-M2 53450 Tw1/0/7 changed state to down.
Dec 30 16:55:40 SG3210XHP-M2 53449 Tw1/0/7 changed state to up.
Dec 30 16:55:41 SG3210XHP-M2 53450 Tw1/0/8 changed state to down.
Dec 30 16:55:43 SG3210XHP-M2 53449 Tw1/0/8 changed state to up.

Similar pattern on the other switch but no indication of what is causing the links to fail.

So I switched over to non-sfp ports on the T1600G and it has been stable ever since.

Now I don't know if the SFP modules are bad or the T1600G switch has a problem with LAGs on SFP.

I'll plug a normal device into one of the SFP and run some tests.

I may also return the SFP modules to Amazon and see if I can get a decent price somewhere for the TL-SM331T

Kind regards

John

  @johndpar, I'm not sure it's a good idea to use load up the SFP+ ports with copper transceivers due to the heat.  If your switch supports DDM you may want to check that too.  It's not supported in Omada controller, only the stand alone GUI or CLI.  You can also try removing the transceivers from ports 26 and 27 to see it 25/28 will work with some breathing room.

I've used 10Gtek's TL-SM331T before and had no issues, but never more than one in the switch.  If you have SFP ports open on the other switch and it's physically nearby, I'd highly recomment using DAC cables (no heat issues).

  @D-C 

The T1600G-28PS is in a very well ventilated cool environment - so I'm not sure heat would really be an issue. POE load on the switch is quite light so the PSU in the switch will not be being stressed. 

The other switch only has two SFP which I'm using for 10G-BaseT connections to servers - no problems with those so far.

No DDM on the V1 version of this switch it seems so no stats on the SFP temperatures.

I'll try doing some perf tests on the SFP ports and see what happens.

Kind regards

John

  @johndpar although your not using 10G SFP+ modules, I think these are good guideleines from Install guide for TP-Link's SM331T module.