On Sat, 23 Jul 2005 20:59:11 -0700 Ben Greear <greearb@xxxxxxxxxxxxxxx> wrote: > Alex Zeffertt wrote: > > > I see your point about leaving the vlan tag in the name but I don't think it is valid in this > > particular scenario. Although each frame sent to the CPU over the MII has a tag, the frame does > > not have a tag when it enters the switch via one of the other ports. Similarly, when the CPU > > sends a frame over the MII it is tagged, but the switch removes the tag before sending it out. > > Therefore the tags are used solely on the MII bus as a way of indicating on which port the frame > > was received/to which port it should be sent. This is an implementation detail that I want to > > hide and make it look like I've just got 10 NICs. > > So what happens when the user configures a VLAN on this 'ethernet' port? > Ben, Very good question. In principle you just get double tagged frames being sent to and fro over the MII port, and single tagged frames being sent to and fro over the switch fabric's other ports. However, in reality it's going to be fiddly to get this to work.... Firstly (and most obviously) you need to choose a switch fabric which can do jumbo frames (i.e. > 1522 bytes). Secondly you need to be able to make the switch fabric ignore any vlan tags on it's non-MII ports, but use the (outer) tag on its MII port. I'm pretty sure I can do this on the 88e9095 by re-configuring the DIX type (used to identify tagged frames on the non-MII ports) from 0x8100 to something reserved. However, I won't know that this will work for sure till I get the eval board. Peter, I'm not familiar with udev, but I'll look into it... it sounds interesting. Alex
