Huawei Technologies Huawei Technologies Tata Communications China Mobile Comcast UC Davis This document presents a list of requirements for OSPF topology- transparent zone in a domain. A topology-transparent zone comprises a group of routers and a number of links connecting these routers. Any router outside of the zone is not aware of the zone. The information about the links and routers inside the zone is not distributed to any router outside of the zone. Any link state change such as a link down inside the zone is not seen by any router outside of the zone.