Club 3D CAC-1520 Adapter, USB 3.2 Gen1 Type-C to 2.5G NBASE-T

[Alex Atkin UK]

Just picked up one of these adapters which is based on the Realtek r8152 for my ITX system as the GPU is taking up the only PCIe slot.

 

Testing to my server which is hooked up over 10G with standard 1500 frames:

iperf3 -Rc lcars
Connecting to host lcars, port 5201
Reverse mode, remote host lcars is sending
[  5] local 192.168.1.94 port 35086 connected to 192.168.1.253 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec   263 MBytes  2.21 Gbits/sec                  
[  5]   1.00-2.00   sec   264 MBytes  2.21 Gbits/sec                  
[  5]   2.00-3.00   sec   265 MBytes  2.22 Gbits/sec                  
[  5]   3.00-4.00   sec   264 MBytes  2.22 Gbits/sec                  
[  5]   4.00-5.00   sec   264 MBytes  2.21 Gbits/sec                  
[  5]   5.00-6.00   sec   264 MBytes  2.22 Gbits/sec                  
[  5]   6.00-7.00   sec   265 MBytes  2.22 Gbits/sec                  
[  5]   7.00-8.00   sec   265 MBytes  2.22 Gbits/sec                  
[  5]   8.00-9.00   sec   264 MBytes  2.21 Gbits/sec                  
[  5]   9.00-10.00  sec   265 MBytes  2.22 Gbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  2.58 GBytes  2.22 Gbits/sec    0             sender
[  5]   0.00-10.00  sec  2.58 GBytes  2.22 Gbits/sec                  receiver

Peak speeds over NFS of 256MB/s from an SSD without any tweaking whatsoever.  Changing the MTU to 9000 doesn't seem to do much pulling from the server, it increased to just 2.23Gbit but triggered a few retries, it did increase sending TO the server to 2.44Gbit however.  Yet in real-world NFS transfers from the server it seemed to be slightly slower peaking at more like 250MB/s with seemingly more fluctuations, possibly due to the concurrent access from other clients using a 1500 MTU (I pull modem stats automatically for logging).  Thus I think I will leave Jumbo Frames off.

 

NFS to NFS transfers from/to the same box are a little odd as they seem to burst then stall, but that might be something in my setup and is certainly never really recommended anyway.  It did seem pretty fast just annoying that access to the network drives would be slow in other windows during the transfer, I was kinda hoping having overhead capacity would avoid that.  Increasing the MTU to 9000 again didn't seem to stop that either.

I did have to compile the driver for Linux so it remains to be seen if Realtek have done a good enough job there for stability, but its looking promising especially as they included the udev rules to load the kernel module automatically so it just works.

For reference, the NIC is plugged into my RTX 2080 USB-C port.  I didn't get the slightly cheaper USB-A model as it was out of stock.

 

So overall first impressions are I'm pleased with the result.  I'm considering hooking up the on-board Intel Gigabit directly to the servers spare on-board NIC as a second channel for NFS mounts.  Not sure how the inbalance in speeds might impact performance but would be curious to see if it makes NFS more response while transfers are taking place.

[Firewrath9]

Wait you can use your GPU virtuallink for actual usb C? 

[Alex Atkin UK]

5 minutes ago, Firewrath9 said:

Wait you can use your GPU virtuallink for actual usb C? 

Absolutely, its a full USB-C port + DisplayPort.

 

The only catch is I'm not sure how it would perform if the GPU was pushing the PCIe interface really hard at the same time, but I'd assume they considered that as a VR headset is likely to use a fair bit of bandwidth and its what its designed for after all.

[Firewrath9]

On 7/10/2019 at 11:24 AM, Alex Atkin UK said:

Absolutely, its a full USB-C port + DisplayPort.

 

The only catch is I'm not sure how it would perform if the GPU was pushing the PCIe interface really hard at the same time, but I'd assume they considered that as a VR headset is likely to use a fair bit of bandwidth and its what its designed for after all.

A 2080 Ti barely saturates a 8x port, you should be good.