[c-nsp] Unified MPLS - Discrete area or separate IGP in Access Layer

[Adam Vitkovsky]

Hi Folks, 

This is regarding Unified MPLS for LTE aka Hierarchical MPLS with RFC3107. 
I'd like to know whether there are networks out there running separate IGP
processes per each access or aggregation network. 
Or whether you are running common IGP and using separate area/level for each
aggregation/access network please? 

I'm interested for any pros/cons either of these solutions have. 
I guess it's no biggie whether there are going to be separate processes in
access and core not talking to each other or just separate areas. 
Thank you very much. 

adam