3 Jun 2021

How to use 3rd party SFP Transceivers / Modules on Cisco Routers and Switches

SFP Modules / Tranceivers
When you plug-in a 3rd party transceiver on Cisco Router or Switch, with terminal monitor on, you will see a log message indicating that the hardware platform has detected an invalid SFP like below:

SYS-3-TRANSCEIVER_NOTAPPROVED:Transceiver on port Gx/x is not supported
PLATFORM_PM-6-MODULE_ERRDISABLE: The inserted SFP module with interface name Gix/y/z is not supported
PM-4-ERR_DISABLE: gbic-invalid error detected on Gix/y/z, putting Gix/y/z in err-disable state

SFP transceivers from different companies all have a burned-in chip that contains info such as serial number, vendor ID, and security info like a Cyclic Redundancy Check (CRC). If any of this info doens’t match the database on the Cisco device, the OS will mark the SFP as not supported and disable the port.

There are some undocumented (and unsupported) commands to circumvent this issue. From configuration mode enter the following commands. Note that since the first command is undocumented you can’t “tab” and “?” your way to the command. You can only type the full command in.
switch#configure terminal
switch(config)# service unsupported-transceiver
switch(config)# no errdisable detect cause gbic-invalid

If nothing happens, remove SFP module, shutdown/no shutdown the port, insert back the SFP module.

The second command is often necessary to disable the automatic port shutdown. On some devices you may not find “gbic-invalid” so replace with “all”; resulting switch(config)# no errdisable detect cause all.
Please note: Using “all”, disables error detection for all applications. A cause will not be detected on an interface, the interface will not be placed in an error-disabled state.
When you enter the first command, you get a warning message:
Switch(config)#service unsupported-transceiver
Warning: When Cisco determines that a fault or defect can be traced to the use of third-party transceivers installed by a customer or reseller, then, at Cisco’s discretion, Cisco may withhold support under warranty or a Cisco support program. In the course of providing support for a Cisco networking product Cisco may require that the end user install Cisco transceivers if Cisco determines that removing third-party parts will assist Cisco in diagnosing the cause of a support issue.

Should 3rd Party SFPs Be Used?

I don’t recommend using non-Cisco SFP's in production environments, however in a lab environment, its a cheap way out. When using 3rd party SFPs, one must keep in mind that Cisco TAC will not provide any support for problems related to the SFPs as they are totally unsupported.