Network interface limit

[luckyjay]

Hi guys, just joined the forums. Absolutely love your products, already have many XU4 and NL2 devices, wonderful hardware!

I have an issue with XU4, when connecting more than 20 external internet modems using an externally powered USB hub(Orico, 30 slots), the system allows only 18 devices to be connected. The output of lsusb shows that all hub ports are recognized but the system itself seems to limit allowing more network interfaces to be created.

The same hardware connected to Debian laptop works just fine and all modems are recognized as internet modems and connect fine so I only assume that XU4 has some sort of limitation per how many devices can be connected as external modems?

How could I avoid this limit or what information I should provide to help debug this issue?

[luckyjay]

It seems to be a limitation of the number of USB endpoints in the SoC root hub.
Look into the dmesg output when you connect 19th device to find possible root causes.

[mad_ady]

A few years ago there was a thread about working with 128 usb-uart adapters, on xu4, if I recall correctly. Not sure if a mainline kernel would help...

But I'm curious - what are you doing with so many modems?

[luckyjay]

A few years ago there was a thread about working with 128 usb-uart adapters, on xu4, if I recall correctly. Not sure if a mainline kernel would help...

But I'm curious - what are you doing with so many modems?

Thank you, will try to dig up that thread!

I create mobile 4g/5g proxies.

[luckyjay]

I get this error message:

usb 3-1.2.3.2.2: Not enough host controller resources for new device state.
usb 3-1.2.3.2.2: can't set config #1, error -12

Does this mean that XU4 cannot support more than 20 USB devices?

A quick search around here told me to check if something changes when using USB 2 instead of USB 3 ports. Will try that.

[mad_ady]

It may be worth it to try older images with older kernels (especially 3.x), since it comes directly from Samsung.

[luckyjay]

I will document my progress here.

I've managed to bypass this error

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Not enough host controller resources for new device state.

By simply using USB2 instead of USB3 port on XU4.

It seems that another limit can be hit:

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avahi-daemon[487]: IP_ADD_MEMBERSHIP failed: No buffer space available

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cat /proc/sys/net/ipv4/igmp_max_memberships

Gives me 20, which is too low as I would like to be able to support at least 40 USB modems per box.

so to do so, I've updated:

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net.ipv4.igmp_max_memberships = 50

in /etc/sysctl.conf

[mad_ady]

But usb2 limits your throughput severely. With 40 modems you'd get 12Mbps max per modem.

[luckyjay]

But usb2 limits your throughput severely. With 40 modems you'd get 12Mbps max per modem.

True, but only if all modems are used on max at the same time which very rarely is the case.

Of course, I would be happy to use USB3, can you suggest a solution for this? I seem to be failing to find one.