Hi Thomas,I found a solution to this problem and verified it's working with 6509-E Sup2T VSS. Please see my other comment to understand how memory for subinterfaces is allocated.There are undocumented commands for Sup2T:platform sub-interface maximum...

Hi,by default (tested on IP services 151-2.SY2) the limit for standard Sup2T is 21 interfaces (± 1 depending on your configuration) with defined subinterfaces. Upon defining subinterface for the 21st interface you hit the rock bottom and it's impossi...