Hi dannyjump and thanks very much for your reply.
I wasn't 100% sure I understood the second part of your first sentence "we can't use it capture [sic] input data, parse this and then write it to the endpoint DB." Though I think i understood the general gist; CPPM Exchange seems to be a tool to allow Clearpass to provide additional information to the offboard context system, to allow it to do it's own job, whereas I'm looking to do the opposite; use info from the offboard system (Good, in this case) to allow Clearpass to make more informed policy decisions (?) Hence you pointing out that an ODBC lookup on Good, for the MAC details it stores seems ideal (if it works!?!?)
Thanks again....
ND