Cisco SFP Transceiver Failure?

I am a complete novice with regard to network switches, and so far I have been guided by informative posts on this forum. I was sucessful with adding a Cisco 2960 to my system to replace a Netgear switch. A couple of weeks ago I decided to try a fibre optic link in the equation and added a second Cisco 2960 switch linking the two switches together using a pair of Cisco GLC-SX-MM 1000Base-SX SFP 850nm LC Transceivers and a 3m length of OM1 62.5 125 Fibre Optic Network Cable Patch Lead LC - LC Multi-Mode. The connection was immediate and appeared stable - until tonight when all signal was lost. There are no lights in either SFP socket and nothing has changed in the setup.
I have used each switch on its own and they both function without a problem. The issue appears to be with the fibre optic link. Could it be that the second hand SFP transceivers have failed?

Gosh……calling @Simon-in-Suffolk ……out of my comfort zone.

I guess hardware failure is always a possibility. I’ve had 3 Cisco switches connected in the same way as yours and they’re been running without a hitch for several years now.
It would be pretty cheap and easy to buy replacement SFPs on eBay, or a new patch cable, and see what happens.
If your IT skills are up to it you should be able to log into the switch and check for any errors, but if you need to figure that out from scratch I would go for the easy option and just replace the components.

It could be a failure… fibre can be less reliable than twisted pair, especially in set up.
Of course the advantage of a managed switch is that you can log onto it and see the status of the interface.

There are many guides of connecting to Cisco managed devices…

Once connected and in enable mode…

#show interface status

and then try
#show interface transceiver

and see what it says….

Are you using Cisco devices or ‘compatible’ devices… it is probably best to use genuine Cisco transceivers … they cost more but you know they work optimally with Cisco devices… but anything can fail… but see what the switch says

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Thank you for the replies. I am using Cisco transceivers as recommended. I will have a go at logging on to the switch(es) and see what is says as you suggest.
In any event this was an experiment and my fall back position is to revert to using just one switch. The system sounded fine in that configuration.
I took the opportunity to move the switches from my hifi rack into my den next door. Short term there is an ethernet cable going out the window of my den and back in the window of my listening room.
I carefully connected the switches up, isolated them, dressed the cables as best I could - and nothing. I then removed and reinserted each of the SFPs and it woke up! It has now been stable for a couple of hours, so I think that my problem was a physical connection issue caused by one of the SFPs slowly working loose in the socket and finally losing contact. Fingers crossed that’s it!
Thank you again for your help folks.

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Good stuff… now there is no pressure it’s always worth learning how to connect to the switch and checking the interfaces …. Kind of like checking which master circuit breakers have tripped on your consumer board… it’s not necessarily a ‘technical’ thing.