In Microsoft Message Queue (MSMQ) Server, a collection of computers between which communication is fast and inexpensive. MSMQ site boundaries usually follow the physical location of the computers, such as all computers within a given building. Computers in an MSMQ site need not run the same network protocol and might not be able to communicate with each other directly.
MSMQ sites are connected to other sites through site links. MSMQ messages are routed through these site links based on cost values assigned to them by administrators.