RPI Pro: Can SFP and LAN Be Used Simultaneously for a Diretta Host/Target Setup?

evolik

Good day.

Question about RPI Pro - can SFP and LAN ports work independently and simultaneously?

There is an idea to use two RPI Pro with Audiolinux to configure the Diretta Host scheme (the first RPI Pro) - Diretta Target (the second RPI Pro) and connect the RPI Pro to each other via SFP or LAN for the cleanest data transfer (while the first RPI Pro will be connected to the AS6 switch via the second free port)

Jayce

evolik

From a hardware perspective, the SFP and RJ45 LAN ports on the RPI Pro are independent interfaces and can operate simultaneously. However, they should not be connected to the same local network at the same time, as they are intended to be used as separate network paths.

Connecting two RPI Pro units directly via SFP or LAN, while using the remaining port to connect to an external switch, is therefore feasible from a hardware standpoint.

Regarding AudioLinux and the Diretta Host/Target configuration, we have not tested this setup on the Raspberry Pi platform. Based on publicly available information, Diretta Host typically requires an x86 system, so we cannot confirm whether the Raspberry Pi version of AudioLinux supports Diretta Host.

If AudioLinux for Raspberry Pi does support Diretta Host, then your proposed topology should not present a hardware limitation. We recommend confirming software support with AudioLinux directly.

evolik

Jayce
I found a discussion of a DIY project https://audiophilestyle.com/forums/topic/71280-diy-a-three-tier-roon-endpoint-with-diretta-on-raspberry-pi with step-by-step instructions for configuring two Raspberry Pi devices as a dedicated Diretta Host and Diretta Target https://github.com/dsnyder0pc/rpi-for-roon/blob/main/Diretta.md

The instructions have a section on setting up the network and explaining why it is worth using point-to-point link with NAT instead of using the simpler network bridge https://github.com/dsnyder0pc/rpi-for-roon/blob/main/Diretta.md#5-point-to-point-network-configuration

FleecyEars

Jayce

Hi Evolik,

Current Setup:

Two LHY RPi Pro (CM4) units - Host and Target PCs
AudioLinux V5, kernel 6.12.77
Diretta Host/Target connected via SFP fibre (Finisar FTLF1318P3BTL)
USB DAC on Target

Here is my challenge, the SFP port on the HOST LHY Rpi Pro is directly connected to another TARGET LHY Rpi Pro with its own IP address range (172.x.x.x) not visible on the primary network). The actual RJ 45 port HOST LHY Rpi Pro is connected to my primary switch using my main IP address range (192.x.x.x). At the moment, Linux sees both networking ports on the HOST as only one (end0). Meaning I cannot treat them independently as you've pointed out - even though the local network is different.

Is there something I'm missing here?

Thanks

FleecyEars

Jayce

Thank you for confirming the SFP and RJ45 are independent interfaces.

However when running AudioLinux V5 on the RPi Pro, only the RJ45 port (end0) appears in ip link show.

The SFP port does not appear at all.

Could you please advise what device tree overlay or kernel module is required to activate the SFP port as a second independent interface under Linux?"

he SFP port on the RPi Pro likely connects through an internal switch chip to the same bcmgenet ethernet controller — meaning it shares end0 rather than being a separate interface. This explains:

in Summary:

Why only one interface appears in "ip link show"
Why both ports share the same MAC address
Why the MTU ceiling is the same 2032 regardless of which port is used

The LHY product page claims support for "DSD 512 (Native DSD)". So you believe your hardware can support DSD512. Therefore, is it safe to say the limitation must therefore be in the software configuration rather than the hardware itself?

Appreciate all your help.

ralong

in this video the author says that it doesnt work.
https://www.youtube.com/watch?v=AI-DLX8EwcU&embeds_referring_euri=https%3A%2F%2Fwww.head-fi.org%2F&source_ve_path=Mjg2NjY

evolik

FleecyEars The LHY product page claims support for "DSD 512 (Native DSD)". So you believe your hardware can support DSD512. Therefore, is it safe to say the limitation must therefore be in the software configuration rather than the hardware itself?

RPI Pro supports DSD 512 Native via USB port (but not via IIS port in the new revision of the device, which only supports DSD 64/128 in DoP mode).

My current setup
Roon -> Upscale to DSD 512 -> RPI Pro (Roon Bridge) -> USB (Gustard X30 DAC with NOS ON and DSD Direct ON mode):

Roon -> Upscale to DSD 512 -> Diretta ASIO Driver (Windows) -> RPI Pro (Diretta Target) -> USB (Gustard X30 DAC with NOS ON and DSD Direct ON mode):

evolik

Hi FleecyEars,

Unfortunately, the situation with simultaneous operation of both interfaces was not the same as described by LHY support. Both interfaces really use the same MAC address and Audiolinux sees them as one network device and both interfaces cannot work at the same time - this was also confirmed by my friend who debugged network packets at a low level.

The situation is similar in Gentooplayer - only one network interface is created in the system:

FleecyEars

The for the reply as this provides encouragement.

My setup is as follows:
.
LHY Audio Switch AS6
.
Connected via Ethernet to USB to
.
Host LHY RPI Pro running Audiolinux and Diretta with Diretta UPnP renderer.
.
Connected via SFP to
.
Target LHY RPI Pro running Audiolinux and Diretta
.
Connected to DAC via USB
.
The playback app is JPlay and Audio Device is Diretta

Therefore bigger Jumbo Frames should work, which would unlock DSD256+ / DXD, unless of course my Host (LHY RPI Pro) is the limiting factor here since you likely have a more powerful x86 based Windows machine?

Thinking of plugging in a Ryzon or an i5 / i7 based HostPC....all passive of course and powered by a Linear PSU and running windows.....What do you think @evolik ?

evolik

@FleecyEars
It is doubtful that the problem with DSD playback is related to the Jumbo Frames - in my setup DSD512 worked also without turning on Jumbo Frames.
Most likely, this is a problem with a specific software configuration and/or compatibility with the DAC.

FleecyEars

Thanks. I've managed to get DSD256 playing relatively cleaning and that's a good step forward after using DDS and Setting Jumbo frames back to 1,500...note, there is no HQPlayer in my setup atm.

Unfortunately, I'm still unable to play DXD cleanly with a constant background hiss.

HostPC
[global]
Interface=end0
TargetProfileLimitTime=200
ThredMode=1
InfoCycle=100000
FlexCycle=disable
CycleTime=1000
CycleMinTime=
Debug=disable
periodMax=32
periodMin=16
periodSizeMax=38400
periodSizeMin=2048
syncBufferCount=16
alsaUnderrun=enable
unInitMemDet=disable
CpuSend=2
CpuOther=3
CPUFLOW=3
LatencyBuffer=0
disConnectDelay=enable
singleMode=

TargetPC
[global]
TrgetName=LHY-Target
VolumeCtl=
AlsaLatency=150
DSDNativ=enable
DSD48=enable
DoPauto=disable
PCM16bit=enable
PCM24bit=enable
PCM32bit=enable
ExtEtherMTU=1500
EtherMTU=1500

FleecyEars

All good now. Was an issue on my end converting DSD256+ files to DXD.

The "scratching" noise I was hearing in my converted DXD files is the DSD noise-shaping hump being carried over into the PCM domain.

Because DXD (352.8kHz) has such a wide frequency response, it faithfully captures all that high-frequency ultrasonic garbage that DSD intentionally pushes above 25kHz.

To fix this, added a Low-Pass Filter (LPF) to the DSD to DXD conversion script.

This "shaved off" the ultrasonic noise while leaving the music untouched.

Back to listening to music again via the two LHY RPI Pros running Audiolinux and Diretta. Roon Server is running on a separate NAS containing the music library.