GOG @ CNES and GIBIS @ CNES are not available anymore.
To generate a new simulation, see the GOG wiki page (http://wiki.cosmos.esa.int/gaia-dpac/index.php/CU2:_GOG) : you can use GOG through a Graphical User Interface or directly as a standalone application.
To access large scale simulations, check the GOG data delivery wiki page (http://wiki.cosmos.esa.int/gaia-dpac/index.php/Project_Office_:_Status_of_Datasets_Status_planned_from_Cycle11_on#GOG_DS) as well as the version available at GACS (http://geadev.esac.esa.int/gacs-dev/).
If you need a GIBIS simulation, please contact gibis.help @ obspm.fr or Carine Babusiaux (carine.babusiaux @ obspm.fr)
For more information, contact Carine Babusiaux (carine.babusiaux @ obspm.fr) or Eduard Masana (emasana @ am.ub.es)