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Re: managed switches on mii(4)

On Tue, Apr 08, 2008 at 08:50:40AM -0600, Herb Peyerl wrote:
> In my day-life, on another NetBSD platform, the hardware has a  
> Marvell switch controlled by ioctl()s sent by a userland  
> application.  It's terribly proprietary and won't see human use, so  
> it's not intuitive and requires a block diagram of the system in  
> order to use. [...]

I have a similar platform, though the switch is a Vitesse chip.  We
control this switch over USB -- I like your configuration tool somewhat
better than ours.  I can't really see how one could use such a tool
without knowing the block diagram of the system, as you note.

A common way to do this on low-cost/low-part-count systems is to use
an Ethernet MAC that does not have an integrated PHY (or to not use
its integrated PHY) and to use one port on the switch in "reverse MII"
mode as a Special PHY.  Most decent switch chipsets have the rMII
feature now, but AFAICT (I have a bunch of databooks here) they do
_not_ allow you to configure the switching engine itself via
manipulating the "PHY" registers.  I can see some good reasons why not
to do that, but without it, you need an out-of-band switch configuration
interface, like the USB we use -- and that's going to be totally switch
specific.  :-/


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