can i make the SA2000 give each user a specific IP from the pool i configured, i noticed that i can do this through rols to give specific range to each role, but can i do that for each user, to have the same IP everytime he connect throught NC?
You can't really do that based on NC pools managed by the SA.
Previously used NC IP's will be cached for a while so if the same user logs in again and the IP is still cached and available from the pool, it will be reused. However, this approach won't work if users reconnect and the IP has been re-used by another user.
The only approach that would work is to assign a pool made of 1 single IP. That means you should create one NC profile per user. We can't really recommend this approach as it would be a nightmare for admins.
An alternative approach is to get the IP address retrieved from a custom LDAP or Radius attribute during authorisation step to store a permanent IP for the user.
You can use variables in NC Resource profile for the pool, e.g: <userAttr.framed-ip-address>
This will ensure users always get the same NC IP's.