Did anyone try this replication Model?

The database, having master-master replication are in different sites. = Each such database may have roll-up databases in subsidiary sites. These = Subsidiary Sites have updatable snap shots of the tables that are = replicated among master-master databases. So any change made at a site = is reflected in all the other sites in due course of time.

If any one attempted this model, please tell me what care I should take = while designing one. What are the possible bottle necks and design = issues. we are using Oracle 8.0.5 Enterprise Servers.