Mutisite is clear case best function. It Supports Geographically-Distributed Software Development.
Geographically-Distributed Software Development includes:
1. Developers are located at several physical sites.
2. Each site develops one or more subcomponents of a large software.
3. Sites have private sources and need to share sources, libraries and header files with other sites.
Time zone differences.
Complicate communication and coordination among team
Services of Multisite:
Maintenance of a local replica of a VOB at each site.
Enforcement of the rule that different sites work on different branches of an element.
Synchronization of the multiple VOB replicas, communicating the changes among the sites via network connections or magnetic tape.
ClearCase merge tools to merge independent changes to the same source file.