OK Catalyst 2960-s doesn't have routing possibility.
But it has another great feature called protected port : two protected ports can not communicate with each other.
I used this feature to divide my network into four segments (see image below) :
- user group1 is on protected port
- user group2 is on protected port
- server group is on protected port
- shared resources are on non protected ports

this does exactly what i wanted to do, but i'm afraid that having all users on a single port will decrease network performance??
in other words, what happens if all users in user group 1 demand access to shared resources?