Hello,
can somebody please explain what the selector under Interfaces → Ethernet → SFP → Rate Select → high/low does?
A Google search was not successful and - as usual - the MT Wiki was a fail too:
sfp-rate-select (high | low; Default: high)
Allows to control rate select pin for SFP ports.
It has something to do with a “control rate pin”, but a datasheet of a common SFP contains no information about a “control rate pin”…
Even the pinout - no high or low control rate pin:
The SFP rate select signal is on Pin 7/RS0 (RS = Rate Select).
The new ROS setting allows to set he state of SFP Pin7/RS0
The SFP specification (not public) says
This is an optional input used to control the receiver bandwidth for compatibility with
multiple data rates (most likely Fibre Channel 1x and 2x Rates). If implemented, the input
will be internally pulled down with > 30kΩ resistor.
The input states are:
Low (0 – 0.8V): Reduced Bandwidth
(>0.8 , < 2.0V): Undefined
High (2.0 – 3.465V): Full Bandwidth
Open: Reduced Bandwidth
Support of rate select is optional and also the definition of “reduced” vs. “full” bandwith is not part of the SFP specification.
Some SFP modules indicate in EEPROM data adr 65 / bit 5 if rate select signal is supported.
If the setting does anything and if yes what it does is depending on the SFP module.
The setting was previously present in RouterOS and removed in v6.37 “*) sfp - removed “sfp-rate-select” as command was not relevant to currently supported hardware;”, so presumably it is now relevant to some supported SFP.
Hi all
I have the following hardware:
SFP+ are normally recognized and work, but loose connectivity after couple of days running fine.
Issue repeats regularly, where SFP+ is always marked as “present”, but connection is lost “RX Loose” after a while.
Sometimes connection is lost immediately with these SFP+ modules and sometimes it takes a while.
Issue is confirmed not present on 1 Gbps SFP modules in the same switch (either MM or SM).
As per info from note #9 on this webpage: _https://wiki.mikrotik.com/wiki/MikroTik_wired_interface_compatibility#SFP.2B_interface_compatibility_with_10G.2F25G_optical_transceivers_
these SFP+ modules should be compatible, as of October 2021 manufactured devices… guess this relates to the switch, not SFP+ modules.
“9. XS+31LC10D, XS+2733LC15D – full support has been added to CSS/CRS326-24G-2S+ and CRS328-24P-4S+ switches manufactured from October 2021.”
So I swapped the cables, switches and SFP+ modules of the same model, but the issue still remains… thus not likely a hardware malfunction of a specific component.
I also tried running on 6.49.6 (stable), but the issue is still the same.
On the same page linked above I have found info on how to apparently get this to work, by issuing this command:
/interface ethernet set sfp-sfpplus1 auto-negotiation=no speed=10Gbps full-duplex=yes sfp-rate-select=low
However, option sfp-rate-select is not present in 6.47.9 (long-term), however 6.49.6 (stable) does have that option.
Interfaces are by default set to “high” sfp-rate-select, but I can switch them all to “low” on 6.49.6.
Either way, after setting all 4x SFP+ with the command above on 6.49.6 like proposed and rebooting the entire switch, issue is still the same.
SFP+ modules are present, set to “low” and manual to 10 Gbps speed just fine, but “no link” status now even after booted up, and it seems to persist never connecting at all anymore.
SFP+ module settings/status are as follows: 1310.00 nm, 43 C, 3.270 V, 41 mA, -8.576 dBm
Judging from the jbl42 post above, this voltage would correspond to the “high” settings for voltage so not sure if settings actually applied.
So my best guess is that it seems “low” setting is not applied, which might be impacting this command not to work as advised.
Can you please advise further?
Thanks,
Tihovsky
Just to add to this old post, this was later documented as compatibility issue of SFP and the switch, but I didn’t re-check if it was also fixed in the meantime.
Learning would be be to check compatibility prior and have both switch and SFP in production at least for a year prior to purchase so any issues get reported and documented.
Hope it helps!
I am having a similar problem. I will recheck it.