Connecting distributed database systems
You can use the distributed data facility (DDF) of DB2® to access data that is held by other data management systems. You can also use DDF to make your DB2 data accessible to other systems.
About this task
DB2 does not place any upper limit on the number of systems it can connect to; available storage is the limiting factor.
- The communications protocols
DDF uses TCP/IP or SNA to communicate with other systems. - The role of the communications database (CDB)
When sending a request, DB2 uses the LINKNAME column of the SYSIBM.LOCATIONS catalog table of the communications database (CDB) to determine which protocol to use. 
The DRDA database protocol
Applications can use the Distributed Relational Database Architecture™ (DRDA) protocol to control remote access.- DDF installation and implications for DB2
The installation options for DDF are described on installation panels DSNTIPR and DSNTIP5.
Parent topic: Working with additional capabilities for DB2
Related concepts: