A system and method for efficient transfer of backup data over multiple networks. A backup server and a client computer are coupled to one another via a network, such as a local area network (LAN). The backup server is coupled to at least one storage server via another network, such as the Internet. This storage server is coupled to another storage server via at least two networks, such as the Internet and a Fiber Channel connection. The at least two networks are discovered and initialized by the two storage servers. Two or more networks may be bonded together in a single logical communication channel for transferring backup data. In one embodiment, the backup data corresponds to a duplication operation. When two or more network channels are included in the logical communication channel, a load balancing scheme is used to assign backup data traffic to appropriate network channels.