English to Spanish Tech/Engineering

Tenía entendido que tier se traducìa "nivel" pero aquì dirìa entonces primero multinivel y despuès dos niveles?? en què quedamos? MUCHAS GRACIAS

The physical security of the XXX Data Center consists of multi level, two tiered access. The data center is centrally located within a secured facility thereby preventing data center penetration from an exterior wall. The building in which the data center is located is secured 24 hours employing a two tiered electronic access control system consisting of an approved access card with appropriate access parameters and an individualized personal identification code. Building access is monitored. Data center access is also controlled by the electronic access control system which requires a unique access level limited to only personnel with established need for access. Facility and data center access is reviewed periodically.