Working USB LAN Adapter?


10 posts
by LightAxe » Mon May 28, 2012 5:53 pm
Has anybody had success with a USB LAN adapter? I'm looking for a specific model to purchase to turn my RaspPi into a router.

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by AndrewS » Tue May 29, 2012 8:58 am
As a practical router, I don't think the Pi would make a very good platform. You'd have both ethernet ports working through the USB bus, which (I suspect) would severely limit the throughput.
But if this just an "experiment" then go ahead ;) From what I understand USB LAN adaptors don't have the 'firmware blob' problems/requirements that USB WLAN adaptors do, so any USB LAN adaptor with Linux drivers should work fine on the Pi.
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by LightAxe » Tue May 29, 2012 3:50 pm
AndrewS wrote:As a practical router, I don't think the Pi would make a very good platform. You'd have both ethernet ports working through the USB bus, which (I suspect) would severely limit the throughput.


Well.... I only have 12Mbps coming in to the house, which doubled or even quadrupled comes in under the max speed USB 2.0 bus speed. As an enterprise router, I'd have to agree, but as a home router, I think it shouldn't cause any limiting.

From what I understand USB LAN adaptors don't have the 'firmware blob' problems/requirements that USB WLAN adaptors do, so any USB LAN adaptor with Linux drivers should work fine on the Pi.


That was my hope! Thanks!

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by abishur » Thu May 31, 2012 12:16 am
I tried it with a trendnet TU2-ET100 and it was crazy slow. I don't think it was an issue of the max usb bus speed, but something definitely didn't work right
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by jbeale » Thu May 31, 2012 12:28 am
There have been reports of the USB subsystem randomly dropping packets, viewtopic.php?f=6&t=5249
and if that is happening, it would definitely not help your throughput.
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by LightAxe » Thu May 31, 2012 7:30 pm
jbeale wrote:There have been reports of the USB subsystem randomly dropping packets, viewtopic.php?f=6&t=5249
and if that is happening, it would definitely not help your throughput.

My USB NIC comes today... hopefully I won't have issues with the Arch kernel.

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by LightAxe » Wed Jun 13, 2012 5:04 pm
As a followup... my NIC works great, but it shares the ASIX driver with the built-in NIC, and when I upload a lot of data, it causes the NIC to report the carrier as being lost for a few seconds before it comes back up, which unfortunately kicks off a series of DHCP lease renewals and results in 15-30 seconds of downtime.

I'll need to find a NIC that uses a different driver, if such a thing exists....
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by AndrewS » Wed Jun 13, 2012 7:55 pm
Setting up a static IP address might make reconnects faster? Or is it both NICs that "fall over"?
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by LightAxe » Fri Jun 15, 2012 10:58 pm
AndrewS wrote:Setting up a static IP address might make reconnects faster? Or is it both NICs that "fall over"?

Only the public-facing NIC fails; my ISP only provides dynamic addresses, so I'm pretty sure things would go south as soon as my DHCP lease is up for renewal...

If I pass -k to dhcpcd, the recovery time is a bit shorter, essentially doing the same thing a static IP would.

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by Wendo » Fri Jun 15, 2012 11:59 pm
There have been a number of posts mentioning that the on-board LAN chip (or more specifically it's driver) is pretty bad, doing something like 8000 interrupts a second even when idle.

There was talk of this being looked at but as of now I don't think I'd want to use that interface for anything you'd like to be reliable. It sounded to me like this was something that could be fixed in the driver as long as those trying to fix it could work out how to use the chip properly (the code is pretty bad and there is little to no documentation)
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