ClearCase MultiSite is an add-on product on top of Rational ClearCase.
It requires an additional license.

It supports an interesting relativistic model: synchronization happens asynchronously in the background, with the result that two sites are never guaranteed to be fully in sync. It is as if each site had its own time, and could see the sequence of events happening at other sites in a order different than theirs.

Every site writes only to the branches it masters (but can read from all branches). This requires thus merging, which is why people are often afraid of it.

Derived objects (as well as some metadata) are not replicated as such.

--MarcGirod