Issues connecting a Fibre connection from a Cisco core switch to a Meraki MX250 switch

[Princechukw]

We currently have a Cisco environment and we are currently changing our devices to Meraki. I ran into an issue when I replaced a Cisco 3650 switch with an MS250. The issues was the Meraki Switch kept alerting with a Very High CRC error and after a few minutes, the Cisco core switch port gets turned off due to those errors. 

I am currently using an Axiom MA-SFP-10gb-LRM-AX MMF module for the Meraki device and the Cisco SFP-10G-LRM MMF on the Cisco Core Switch. 

When the errors is cleared from the Cisco Core switch, the connection is regained on the Meraki switch however it still has the CRC error. After a few minutes, the Cisco core switch shut down again. 

Note: When the Cisco core switch is connected to the Cisco 3650 switch, with the Cisco module, everything works just fine. 

Not sure what the issue is here

[alemabrahao · Accepted solution]

CRC error means L1 issue, check the fiber and also the SFP.

[DarrenOC]

Try re-patching the fibre into a different connection on your patch panel if you have spare capacity 

[KathleenJ]

Try a new fiber cable and try cleaning the optics on the transceivers. In my experience, CRC's are either a bad cable, dirty optics or if this doesn't resolve the issue a bad transciever.