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New Member

cisco 3750 LED status

Hey guys,

We installed 2 stacked 3750 switches yesterday on site with a load of VOIP devices hanging off them.

all of a sudden on the stacked switches the LED's would go off in pairs. I've looked through the documents but can't find anything relating.

Any ideas at all?

We have a lot of multicast traffic going over these switches and we are using IGMP snooping.


Everyone's tags (4)

Re: cisco 3750 LED status


What version are you running?

Which leds are going offline?

Are you seeing any impact on the network?

You might want to check these 2 defects as well:

CSCsy79004 - wrong led was lit on uplinkport

CSCti09726 - Out of control Ethernet port LED after pressing the Mode button to STAT

Best regards,


New Member

Re: cisco 3750 LED status

Hey Andreas,

c3750-ipbase-mz.122-35.SE5/c3750-ipbase-mz.122-35.SE5.bin is the version that the switch is running.

The switches are 2x48 port poe and 1x24 port poe stacked. one of the 48ports is the master switch and the rest our members.

the engineer out on site yesterday had described to me that all of a sudden the link lights on the ports would go out in pairs after the switch ports would be flashing away. they would go out and work their way down the switch and then it would all go back to normal. This is what I've been told.

There was no impact on the network that we know of and if there was I'm sure we would have known about it and known very quickly given the circumstances.

The whole switch stack was only being utilized by 25% and although the switches are power over etherner we were not using POE.

I hope this information helps



Re: cisco 3750 LED status

Hi Joe,

Thanks for your reply. It's difficult to tell what could be the reason for this based on this information.

Is this issue seen on all switches?

Is this issue seen on all ports?

Is this issue seen on all ports at the same time?

On the other hand, if you're not experiencing an actual impact in the network traffic, I would not worry about the LED status, it does not tell too much anyway. Especially because you mention that it goes back to normal eventually.

I would recommend just to monitor the switches and make sure there's no impact in the network traffic, then you'll be fine.

Best regards,