This paper introduces a fault-tolerant group communication protocol that is aimed at grid and wide area environments. The protocol has two layers. The lower layer provides a total order of messages in one group, while the upper layer provides an ordering of messages accross groups. The protocol can be used to implement sequential consistency. To prove the correctness of our protocol we have used a combination of model checking and mathematical proofs. The paper also presents the behavior of our implementation of the protocol in a simulated environment.