The interconnect is the networking layer of Greenplum Database. When a user connects to a database and issues a query, processes are created on each of the segments to handle the work of that query. The interconnect refers to the inter-process communication between the segments, as well as the network infrastructure on which this communication relies.
To maximize throughput, interconnect activity is load-balanced over two interconnect networks. To ensure redundancy, a primary segment and its corresponding mirror segment utilize different interconnect networks. With this configuration, Greenplum Database can continue its operations in the event of a single interconnect switch failure.
When a cluster contains multiple racks, aggregation switches must be used to connect the Interconnect network in each rack. In a multiple rack system, there are two aggregation switches; cabling is run from all Interconnect 1 switches to one aggregation switch and from all Interconnect 2 switches to another aggregation switch.