1. We would like to pre-provision a 2248TP FEX on my 5596UP (NEXUS 5596 running 5.1(3)N2(1a)). Problem is that I can't choose this FEX model. I have the choice of a 2248T or a 2248TP-E, but no 2248TP. What do we need to do ?
As far as I understand from your case description you are checking which type of FEX should be taken in order to pre-provision your 2248TP chassis. Besides of that you are looking for number of fabric extenders which N5k-C5596 chassis can handle with L3 daughter card installed.
So let’s start with first question. Definitely you are right, at first glance NX-OS gives you not full list of fabric extenders: