– Below is an issue that we have encountered with multiple customers using UbiSwitch with SFP modules –
I am using UbiSwitch with a 10G fiber SFP. I connect it to a media converter and then connect it to a PC (let’s call this PC A).
Then, on one of the 1G copper ports on UbiSwitch, I connect it to another PC (let’s call this PC B).
The two PCs can’t see each other, what’s going wrong?
There’s a lot going on here so let’s start by drawing a diagram.
There’s many things in this link, so to debug, let’s start at the basics.
Pinging between two PCs
First connect your two PCs directly with an ethernet cable. If they can’t ping, then check your firewall and network adapter settings. If they can’t ping with a straight ethernet connection, then it sure won’t work with any additional hardware in the loop.
Once this is working…
Check your SFPs and Fiber are actually compatible
There are many different flavours of SFP and fiber, you should check that they’re actually compatible. Use media converters to test that they are, or check the datasheet.
Once this is working…
Check what speed the media converter is connected to PC B
What we’ve seen is that the speed of the link between PC B and the media converter actually effects the setting of the SFP port (Port 9) on UbiSwitch.
If your RJ-45 to PC B connection is only 1Gbps, then you will need to set SFP port 9 to “sgmii” mode. To do this, go into the UbiSwitch Serial port and type in
port 9 mac mode sgmii
If your RJ-45 to PC B connection is 10Gbps, then the SFP port 9 needs to be in “10gbaser” mode. This is the default mode of UbiSwitch, if you’ve set it to something else, then use the command below to set it back to 10GBASE-R
port 9 mac mode 10gbaser
The strangest thing about all this is that the SFP port speed seems to need to match the speed that is on PC B. We didn’t expect this, and thought it would automatically adjust.
FYI to be able to update the speed of the SFP ports, you’ll need to make sure your UbiSwitch is running BloxOSLite version 0.4.0. Below is a guide on accessing the serial port.
If your UbiSwitch is running an older version, you’ll need to first update the firmware by following the instruction in the link below.
The speed of the media converter connected to PC B is only 1Gbps, so we set the SFP port 9 to sgmii mode, but the two PCs can’t still see each other. Is there any other way to solve the problem?
Please share more information. What SFP are you using, what is the make and model of the media converter, and how is the other PC connected to UbiSwitch?
PC B connected to the media converter, SFP from the media converter connected to SFP (port 9) using the 10G SFP. PC A connected to the port 1 of the Ubiswitch.
The SFP and media converter used
Thanks for sharing.
First question, with port 9 set to SGMII, do you see any LEDs flashing on UbiSwitch? And if so, do they flash together? Then set it back to 10gbaser and let me know what the LEDs look like. A photo would be great.
Second question when you take UbiSwitch away, and just connect the RJ-45 from the media converter to PC A, then can PC A and PC B ping each other?
Interesting. So the two PCs can see each other when port 9 on UbiSwitch is set to 10gbaser, but the link has a low data rate.
Have you have tested a direct link between PC A and PC B (with the media converters too)?
I have ordered some of those SFPs so will replicate your setup in our lab on Monday.
I ran some tests in our lab, below is a rough photo of my setup. The purpose of my tests was to first replicate your issue and then vary the UbiSwitch SFP port configuration and the Mac laptop ethernet port configuration. The UbiSwitch software version I used was 0.4.1, but I saw the same behaviour on 0.4.0 (which is what you currently have.
Below is a list of the equipment
1 x SFP-10G-BX (1330/1270nm, 10km)
1 x SFP-10G-BXX (1270/1330nm, 10km)
1 x SM fiber
1 x UbiSwitch (revision B, running 0.4.1 firmware)
1 x Raspberry Pi
1 x 10GBASE-R (SFP) to 10GBASE-T converter
1 x 10GBASE-T to USB converter
1 x Mac laptop
Test 1
UbiSwitch port 9 mode: 10gbaser
Mac Laptop Ethernet port speed (via Ethernet to USB converter): 10GBASE-T
Test 2
UbiSwitch port 9 mode: sgmii
Mac Laptop Ethernet port speed (via Ethernet to USB converter): 10GBASE-T
iperf test (Mac to Raspberry Pi)
iperf test (Raspberry Pi to Mac)
Test 3
UbiSwitch port 9 mode: 10gbaser
Mac Laptop Ethernet port speed (via Ethernet to USB converter): 1GBASE-T
No link
Test 4
UbiSwitch port 9 mode: sgmii
Mac Laptop Ethernet port speed (via Ethernet to USB converter): 1GBASE-T
iperf test (Mac to Raspberry Pi)
iperf test (Raspberry Pi to Mac)
Summarising these results…
UbiSwitch Port 9 = 10GBASE-R and Laptop eth port = 10GBASE-T
Laptop to Pi ~ 487Mbps (inconsistent) 
Pi to Laptop ~ 880Mbps (consistent) 
UbiSwitch Port 9 = SGMII and Laptop eth port = 10GBASE-T
Laptop to Pi ~ 692Mbps (inconsistent)
Pi to Laptop ~ 914Mbps (consistent)
UbiSwitch Port 9 = 10GBASE-R and Laptop eth port = 1GBASE-T
No Link
UbiSwitch Port 9 = SGMII and Laptop eth port = 1GBASE-T
Laptop to Pi ~ 858Mbps (consistent)
Pi to Laptop ~ 918Mbps (consistent)
What I can infer from these results is that the rate of all parts in the network need to be the same speed.
Can you tell me what speed the port on your PC B is set to? You’ll need to go into network adapter settings. Set it to 1GBASE-T and let me know what you see.
