1G SFP stays dark in a DrayTek VigorSwitch FX2120 SFP+ cage while the same module links elsewhere
I look after a small office network and put in a DrayTek VigorSwitch FX2120 to get a 10G core. Both 10G links, to the router and to the NAS, came up on their own within seconds. What I cannot do is get a single 1G device onto the switch through the SFP+ cages.
- Switch: DrayTek VigorSwitch FX2120, firmware 3.7.2
- 1G SFP module in one of the SFP+ ports, port speed left at Auto
- The same module links without complaint in the old 1G switch it came out of
- Also tried a 1G DAC towards that same old switch
port with the 1G SFP: LED dark, no link, port shown as down in the web UI
same cage with a 10G module: link up to the router
same 1G SFP back in the old box: link upWhat I tried: reseated the module, moved it to a different SFP+ port, swapped the patch cord, and used the DAC instead of the optic - the DAC behaaves exactly the same, dark port. Nothing on the port page says the module is rejected or unrecognised, it just never links.
Are 1G modules simply not usable in these SFP+ cages, or is there a setting I have not found?
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Comments 3
Nothing is broken. On the FX2120 with firmware 3.7.2 and earlier the SFP+ cages do not auto-detect the rate of a slower pluggable, so a 1G module or a 1G DAC sits there daark until you pin the port speed by hand. Auto is not going to help you - in these cages it effectively means 10G.
In the web UI switch to Advanced Mode, open Configuration and then Port Setup, and change that port's speed from Auto or 10G to 1000M. The LED on the SFP port goes green as soon as the link is up. Do it per port, it is not a global setting.
If the UI is not reachable, the same change works from the console with an RS-232 DB-9 to RJ-45 adapter at 115200 baud:
And if you cannot reach the switch at all because it never got an address, it falls back to 192.168.1.224 with admin/admin, or you can pick it up through the External Devices menu of a Vigor router or with the DrayTek Device Finder. Worst case, uplink it at 10G to a Vigor3910 with the bundled SFP+ cable purely to get into the UI, then set the 1G ports.
Worth remembering the pattern, because it is not a DrayTek quirk: a UCS 6248 flags a genuine GLC-SX-MMD as SFP Validation Failed until the port is switched from the default 10 Gbps to 1 Gbps. The opposite case exists too - on QNAP QSW managed switches the data mode of SFP+ ports cannot be adjusted in QSS at all, only on the RJ45 ports, so there you are down to a module the port happens to recognise or a DAC.
Before anything else: have you tried pinning that port's speed by hand instead of leaving it on Auto, and if you do the same on a second SFP+ cage, does the 1G module come up there? And what does the port page show for the port with the module seated - a configured speed and a link state, or a blank row?
A 10G module lighting up the same cage, and the 1G optic working in another switch, means the hardware is fine on both ends - which usually leaves the port configuration. Also make sure you are in Advanced Mode in the web UI, because a good half of the port settings are hidden in the simple view and people conclude the knob does not exist.
Confirmed, and it took about a minute. Advanced Mode, Configuration, Port Setup, porrt speed from Auto to 1000M, and the LED went green almost immediately - link up to the old switch, traffic flowing.
The 1G DAC came up the same way once I set 1000M on its port as well, so it was never a module problem. For anyone landing here later: the speed is set per port, so repeat it on every cage where you want 1G, and leave the cages carrying 10G alone.