One of my customers has approx 100 Linux desktops of every flavour under the sun and has been having a problems trying to get consistant access..The standard documentation was somewhat lacking so after an extended discussion with TAC, I've got some reasonably detailed information. I've attached it for public consumption in the hope that it will save others time. Kudos to JP in the TAC for dragging this information out of the devs, it is much appreciated. Hopefully at some stage there will be a proper KB article about this or it will be included in the standard documentation eventually.
Obviously use at your own risk, but the source is pretty reliable!