I have 2 Cisco SG500X switches that I want to stack over 10G fiber. I have two 3rd-party SFP-10G-SR modules which I'm having trouble with.

Should SFP modules be detected by the switch when plugged in, regardless of whether fiber is attached? I've checked logs when attaching/removing the modules and nothing shows up. I'm trying to figure out if the issue is with the modules or the fiber. Thanks.

  • I know that in general, switches can be very picky about after-market SFP modules (they don't like them). Are you 100% sure they are compatible? Of course Cisco won't tell you because they want you to buy OEM. – SamAndrew81 Jul 13 '17 at 17:39
  • I've seen a lot of people using 3rd party modules getting error messages about the incompatibility. But I'm not seeing anything. :\ The manufacturer is willing to accept a return of the modules, I'd just like to make sure it's not my switches/fiber that's the problem. If I knew for sure that I should be able to see the SFP modules show up in logs and they're not doing that, I'd just return them. – Duncan Fairley Jul 13 '17 at 18:13

With IOS, you will not detect non-Cisco SFP modules until you enter the hidden command service unsupported-transceiver in configuration mode.

Note that this is a hidden command, so completion is not available while typing the command.

On this example, with a Cisco 3750 switch, you will notice the warning displayed by IOS when you activate this service:

user#conf t
user(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.

Answer to your first question: YES, SFP modules will be detected by the switch when plugged in, regardless of whether fiber is attached or not. But only after having entered this hidden command.

  • The SG500 series doesn't run IOS, but thanks. – Duncan Fairley Jul 31 '17 at 20:58
  • Sorry, I had forgotten that, since a lot of console commands on Cisco Small Business switches are quite similar to IOS ones (but unfortunately, for some Cisco Small Business routers, like the RV220W, it is not the case). If that can help, on my SG300 (that is a Cisco Small Business switch, like your SG500X), when I put one 1 Gbit/s Brocade SFP transceiver, It works without the need to enter any specific command, and I get the following message on the console, even when there is no fiber attached to the transceiver : Fiber-I-SFP-PRESENT-CHNG: gi9 SFP status is present. – Alexandre Fenyo Jul 31 '17 at 22:29

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