Linux and Windows has always been separated environment from each other and rarely any interpretability was seen. Now a days as IT field grows rapidly, you got better chance if your company users more effective technologies and share the infrastructure which in turn become cost effective.
Our approach was to use the Active Directory Authentication for login in to a Linux client rather than using a separate directory service for Linux. Main reason for this was as most of the leading companies Srilankan Airlines use the Active Directory environment for authenticating their users. If we use two separate directory services, for Linux and Windows it become hard to manage and the user would have two identities on the network.