Problems w/ USB-ethernet device

Hal Murray hmurray at
Tue Mar 24 01:09:37 EDT 2009

I have a USB Ethernet dongle.  lsusb says:
  Linksys USB200M 10/100 Ethernet Adapter
It was the cheapest available at Frys a couple of years ago when I first got 
an XO and needed some way to connect it to the world.

I just ran some quick TCP tests with it plugged into a XO.  I had no troubles 
getting over 90 megabits/sec throughput.

I'm far from a USB wizard so be suspicious...

USB has 3 speed grades.
  Low is 1.5 megabits/sec
  Full is 12 megabits.
  High is 480 megabits.

Several of the PCs I've worked with had connectors for 8 USB ports on the 
motherboard.  (Maybe not all of them are available on external connectors.)  
The catch is that the internals are really 4 Full speed ports, each going to 
a 2 port hub.  There is a single High speed port that switches in somehow.  
The net result is that you only get 1 High speed port.

You can see that if you do a lspci.  UHCI are the Full speed ports.  EHCI is 
the High speed port.  (At least with that type of system.)

You can get the bus numbers from /var/log/messages at boot time.  You can see 
what bus a port is connected to by watching /var/log/messages when you plug 
something in or unplug it.  You might get lucky by plugging your NIC into the 
right slot.

You learn something out by looking at all the fine print you get from lsusb 
-v.  I'd have to work a bit to decode all that stuff.  I've seen some stuff 
about reserved bandwidth.

I'm now close to the end of my knowledge about this area.

I'd expect that 12 megabits (per NIC) would be enough.  What is the XS 
talking to that needs more than that?

These are my opinions, not necessarily my employer's.  I hate spam.

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