[SOLVED] SFP (fibre optic) module in Slackware 15

radboud · 01-19-2023, 07:58 AM

Hi all,
I am trying to get a fibre-optic SFP module working under Slackware 15 (64 bits)
The SFP slot works fine when I insert a SFP module with a rj45 port, but I can not get a link when I try a fibre optic module.
The module is the correct wavelength and mode (1310, multimode) for the device and cable I am trying to communicate with.
The rest of the set-up (media converter Westermo MCW-211 MM-SC2 and the f.o. cable) have been tested against a switch which also has a SFP module with the same specs.

The module is detected as shown by this command:

Code:

root@calVwr05:/sys# ethtool --module-info eth4
        Identifier                                : 0x03 (SFP)
        Extended identifier                       : 0x04 (GBIC/SFP defined by 2-wire interface ID)
        Connector                                 : 0x07 (LC)
        Transceiver codes                         : 0x00 0x00 0x01 0x20 0x00 0x00 0x00 0x00 0x00
        Transceiver type                          : SONET: OC-3, short reach
        Transceiver type                          : Ethernet: 100BASE-FX
        Encoding                                  : 0x03 (NRZ)
        BR, Nominal                               : 200MBd
        Rate identifier                           : 0x00 (unspecified)
        Length (SMF,km)                           : 0km
        Length (SMF)                              : 0m
        Length (50um)                             : 2000m
        Length (62.5um)                           : 2000m
        Length (Copper)                           : 0m
        Length (OM3)                              : 0m
        Laser wavelength                          : 1310nm
        Vendor name                               : KTI Networks
        Vendor OUI                                : 00:40:f6
        Vendor PN                                 : SFP-FC-M-A-A
        Vendor rev                                : 0000
        Option values                             : 0x00 0x12
        Option                                    : RX_LOS implemented
        Option                                    : TX_DISABLE implemented
        BR margin, max                            : 0%
        BR margin, min                            : 0%
        Vendor SN                                 : L120100304
        Date code                                 : 210702

But the result is still

Code:

root@calVwr05:/sys#  ip -d -s link set dev eth4 up
root@calVwr05:/sys# ip -br a
lo               UNKNOWN        127.0.0.1/8 ::1/128
...
eth4             DOWN           192.168.30.3/24
...

Even though I do get the link led's in the media converter when I connect the f.o. cable.

I suspect I will need the phylink module for this to work, so I tried modprobe phylink, it loads, but I am not sure that it is associated with this specific interface, which is eth4. (loading the module did not solve the problem).

Any hints, do I maybe need to recompile the kernel which specific modules ?
I think it is the standard precompiled SL15 kernel I am running:

Code:

root@calVwr05:/sys# uname -a
Linux calVwr05 5.15.19 #1 SMP PREEMPT Wed Feb 2 01:50:51 CST 2022 x86_64 Intel(R) Core(TM) i5-9500TE CPU @ 2.20GHz GenuineIntel GNU/Linux

smallpond · 01-20-2023, 11:39 AM

I would not expect you to need phylink, but you can remove all doubt by rebooting with the module plugged in. phylink should only be needed for hot plug events.

I took a look at the spec sheets for the KTI SFP and the Westermo MAC and don't see any problem. I assume you are not using more than 2Km of cable.

To clarify, you should have several LEDs on the MAC: FX for good FX link, DPX for full duplex, and PWR for power.
I guess you have no lights on the SFP end? What card are you using?

henca · 01-20-2023, 01:07 PM

Some possible pitfalls:

Connecting one fibre between the two leds (tx) and one fibre between the two receivers (rx) instead of tx to rx.
Using the wrong kind of fibre for the transceiver
Using a transceiver not accepted by the switch (at least SFP+ switches usually only accept a limited number of transceivers from their own brand)
Firbre bent with too small radius (you should not bend it with a radius smaller than about the radius of a tennis ball)

regards Henrik

slac-in-the-box · 01-20-2023, 04:11 PM

Quote:

Originally Posted by radboud

Any hints, do I maybe need to recompile the kernel which specific modules ?
I think it is the standard precompiled SL15 kernel I am running

If you search the config file for a module, you can see if its installed, and in the case of SFP, it is availble as a module in the stock slackware64-15.0 generic kernel:

Code:

grep SFP /boot/config
CONFIG_SFP=m

Ser Olmy · 01-21-2023, 05:56 AM

Since you say that the module works when plugged into an SFP slot in a switch, I'll assume the modules and cabling are OK.

This SFP slot on the Linux system must belong to a NIC, which in turn is driven by a specific module (driver). So which kernel module is associated with eth4?

I also noticed this:

Quote:

Originally Posted by radboud

[CODE]root@calVwr05:/sys# ethtool --module-info eth4
Identifier : 0x03 (SFP)
Extended identifier : 0x04 (GBIC/SFP defined by 2-wire interface ID)
Connector : 0x07 (LC)
Transceiver codes : 0x00 0x00 0x01 0x20 0x00 0x00 0x00 0x00 0x00
Transceiver type : SONET: OC-3, short reach
Transceiver type : Ethernet: 100BASE-FX

100Base-FX? Is that correct? If so, the tranceiver must be pretty ancient. Alternatively, the driver is getting it wrong and that's why you're not getting a working L2 connection.

BTW, how did you determine that no data is being sent and/or received by eth4?

radboud · 01-21-2023, 08:21 AM

Thanks for the replies everybody !

Unfortunately I am not at the system at the moment (but am able to connect to it remotely).

I am using a short (cyan colored) patch cable, which has the words multimode and the wavelength 1310 printed on the cable itself, so I am pretty sure the cable is the correct specs.

As for the test I did with this Westermo and this same cable, they were against another switch (Moxa EDS) with a SFP module which belongs to that switch, which is not the SFP module I am trying to get working in this computer running Slackware.
I did try this Moxa SFP module in the computer as well and got similar results to this KTI module.

By the way, the computer is an industrial all in one PC with two built in SFP slots.
this is the PC: https://www.nexaiot.com/en/product/I...puter/CE-CL-DC

The LED's on the Westermo looked o.k. to me, with LED's lighting up when I connect the cable.
There are no LED lights on the SFP module or socket at the computer end.

Thanks for the remark about Phylink, I guess I was confused as to what exactly phylink does.

I did try swapping the FX and TX fibres at the Westermo end, and got less LED's on the Westermo, so I swapped them back (also did not get a link on eth4 in SLackware).

I do have the line: CONFIG_SFP=m in /boot/config.
There are no modules with sfp in the name showing up using lsmod, shouldn't there be ?
After I do modprobe sfp, it does show up in lsmod, but I still do not get a link on eth4 after I do "ip -d -s link set dev eth4 up"

"BTW, how did you determine that no data is being sent and/or received by eth4?" I do not get a 'link up' on eth4 and do not get a reply using ping on that network segment.

the only driver currently bound to this slot is igb:

Code:

root@calVwr05:/lib/modules/5.15.19/kernel# lspci -s 05:00.0 -nkv
05:00.0 0200: 8086:1536 (rev 03)
        Flags: bus master, fast devsel, latency 0, IRQ 16
        Memory at a1500000 (32-bit, non-prefetchable) [size=1M]
        I/O ports at 4000 [size=32]
        Memory at a1600000 (32-bit, non-prefetchable) [size=16K]
        Expansion ROM at a1400000 [disabled] [size=1M]
        Capabilities: [40] Power Management version 3
        Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+
        Capabilities: [70] MSI-X: Enable+ Count=5 Masked-
        Capabilities: [a0] Express Endpoint, MSI 00
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [140] Device Serial Number 00-10-f3-ff-ff-a5-a7-cf
        Capabilities: [1a0] Transaction Processing Hints
        Kernel driver in use: igb
        Kernel modules: igb

I now think I am missing the sfp driver linked to this specific slot, am I correct ?

smallpond · 01-21-2023, 12:03 PM

igb/e1000 has its own code to talk to the PHY, so no other driver is required. Since ethtool can see the PHY the software is working properly. Code is at https://elixir.bootlin.com/linux/v6....gb/e1000_phy.c

Are you connecting to the Westermo directly, or are you connecting both to a switch?

avian · 01-21-2023, 02:39 PM

Quote:

Originally Posted by radboud

the only driver currently bound to this slot is igb:

Code:

root@calVwr05:/lib/modules/5.15.19/kernel# lspci -s 05:00.0 -nkv
05:00.0 0200: 8086:1536 (rev 03)
        Kernel driver in use: igb
        Kernel modules: igb

I now think I am missing the sfp driver linked to this specific slot, am I correct ?

Nope. Smallpond is definitely correct. I used to run an SFP with a card using the igb kernel module, and its all you need - there is no need for separate SFP modules.

I couldn't see if you answered it elsewhere, but I also find the "Transceiver type : Ethernet: 100BASE-FX" to be a little odd, is that a speed the SFP modules on both ends are compatible with? and is the switch compatible with it? I imagine most equipment these days isn't, and most 1 Gigabit/sec modules dont auto negotiate transmission speed down to 100BASE-FX.

radboud · 01-23-2023, 01:35 AM

there are no switches in between, I connected the utp wired end of the Westermo to my laptop when I was at the system, but when I left I just connected it to another ethernet port on the same Nexcom computer I have the SFP module in, to make sure there is a link at that end.

I will be at the system later today and try to make more sense of the LED's on the Westermo regarding the speed.
Weird thing is that this Westermo has more LED's than it says in the manual...

radboud · 01-23-2023, 08:33 AM

as for the LED lights on the Westermo, the following are lit: pwr, FX DPX, link TX and this one is flashing: link FX
I have a picture of one of these devices in a working setup, which has the same LED's lit (as its a picture I cannot be sure about the flashing of 'link FX', it is 'on' in the photo)

"100Base-FX? Is that correct? If so, the tranceiver must be pretty ancient. Alternatively, the driver is getting it wrong and that's why you're not getting a working L2 connection."
I think it matches these specs of the KTI module:

Code:

SFP FC MAA
Area of application:	Industry
GBIC form factor:	SFP
GBIC type:	        duplex
Fiber optic connector type:	LC
RX Wavelength:	        1310nm
TX wavelength:	        1310nm
DDM:                    without DDM
Fiber Optic Range:	Multimode 2km
Temperature range:	-40°C to 85°C
Fiber Optic Speed:	100M
Wavelength:	        1310nm

from ( https://kti.de/produkte/sfp-module/i...-fc-m-a-a/2862 )

smallpond · 01-23-2023, 12:57 PM

Industrial modules tend not to be bleeding edge. The 100BASE-FX is typical.

I can't see anything wrong with what you're doing. If you can find a switch that supports it, I would try with a switch in the middle just to see which side isn't linking.

babydr · 01-23-2023, 04:49 PM

@radboud , Can you or know someone who has access to the switch that the fiber is connected to ?
If so , try getting a 'show ...' status of the other end . In order to determine that the switch end is negotiating at 100fx .
doing this should give you the necessary info to move forward .

As Avian mentioned below , the above should give you the answer he suggests you look for .

Hth , JimL

radboud · 01-24-2023, 06:57 AM

Ok, so I did some more testing and found something strange:

Two identical Moxa SFP modules (850nm, multi-mode) were inserted in both slots of the computer, connected with a patch cable, didn't get a link on the interfaces in Slackware 15
Installed Windows 10 on the PC and did see a link on both interfaces
rebooted to Ubuntu (usb), and did get state UP and link with 'ip a'
re-installed Slackware 15 without removing any modules or cabling and did not get a link (!)

So I am back to thinking it is a software / driver problem...

Ser Olmy · 01-24-2023, 07:22 PM

So it seems to work with Ubuntu but not with Slackware?

Which kernel versions were the respective distributions running?

Did you manually configure both interfaces in Slackware?.

radboud · 01-25-2023, 07:51 AM

Slackware (15.0 , 64 bits) runs: 5.15.19 #1 SMP PREEMPT Wed Feb 2 01:50:51 CST 2022
Ubuntu (22.10) is running: Linux ubuntu 5.19.0-21-generic #21-Ubuntu SMP PREEMPT_DYNAMIC Wed Oct 12 18:33:17 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

Do you think I should try a newer kernel in Slackware 15 ?
I will try with a live version of Slackware current next week.

I will use the interface with a manual configuration yes, but first I am just trying to get a link status reported..