Thank you both @ReneMolenaar & @lagapidis
I think Cisco not mean OSI layers model in this sentence instead they are meaning virtualization layers, also when I make a little search about that I found something interesting and it’s very related to virtualization function which is what this post about, in short virtualization layer mean at which level we can mange physical hardware resources for example host (Hypervisor) level, guest OS level, or program level (High-level language virtual machines), and so on, I revert this info from this wiki :-
http://en.dwhwiki.info/concepts/virtualization-layer
Also I’m junior in virtualization field and does not have much info about virtualization environment, thus I did not know why Cisco focus on L4/L6, but I find this article and see that L4/L6 are almost talking about storage and network :-
https://virtualizationreview.com/articles/2014/10/14/7-layer-virtualization-model.aspx
Finally I’d like to share this draft from ieft and I think it’s have some info that could be very useful in this subject, but again it’s hard for me to understand it because as I said before I’m junior in virtualization field :-
https://tools.ietf.org/id/draft-shytyi-opsawg-vysm-06.html
Hussein