MySQL replication between datacenters
I would definitely use a DRBD pair in one DataCenter and a DRBD pair in the other DataCenter.

I have written posts about using DRBB in this way:


Mar 29, 2011 : MySQL high availability, failover and replication with Latency
Mar 26, 2012 : 3 Databases, Best Replication Setup?
Aug 20, 2012 : Best solution for cross-datacenter MySQL master-slave replication


Note that each DRBD pair would have a DBVIP for doing local failovers. Just setup Circular Replication between the DBVIPs only (which would be between the DRBD Primaries of each DataCenter).

Since you need MySQL Replication in addition to all this, I would use Semisync Replication to lower sensitivity to network latency.

Give it a Try !!!