Coupling channels

Communication among LPARs can be facilitated by Coupling Facility (CF) links. Coupling Facility links are used to support the cross-system Coupling Facility, or XCF. The XCF component in turn can be used to support the IP protocol.

There are two ways to define IP connectivity over a Coupling Facility link:

Static XCF: Static XCF links can be defined to TCP/IP on z/OS using hardcoded statements.
Dynamic XCF: Dynamic XCF links can be automatically generated any time TCP/IP becomes active within a sysplex.

Note: z/OS hosts interconnected using XCF are said to be tightly coupled hosts. In z/OS, a group of tightly coupled hosts are referred to as a sysplex.

XCF communications can flow over copper or fiber media. Over fiber media, the maximum data rate is 200 MBps. Additionally, coupling channels are not CCW-based channels.