10.4 Communicating with the outside world

We have covered communications inside the mainframe; let us now look at communications with the outside world. High-speed communications between the mainframe and external networks are primarily supported through these communication adapters:

• Open Systems Adapter-Express (OSA-Express)

  This TCP/IP-based adapter is important for server consolidation, because it is designed to communicate between a consolidated server environment (that uses virtual adapters and IP addressing) and the "outside world." The OSA-Express adapter can use the QDIO architecture to provide direct connectivity between applications running in a Linux guest or Linux LPAR, and the other platforms on the attached network. The OSA-Express adapter consists of different features: Gigabit Ethernet, Fast Ethernet, ATM (asynchronous transfer mode), and Token Ring.

• Channel-to-channel (CTC) adapters (ESCON and FICON)

  A CTC connection is the typical point-to-point high-speed connection between mainframes. The Linux on zSeries CTC device drivers can be used to establish a point-to-point TCP/IP connection between two mainframe Linux systems, or between a Linux system and another operating system such as z/VM, VSE/ESA, or z/OS.

For a description of the features and adapters, see 20.4.8, "Network device drivers and adapters."