HiperSockets

HiperSockets™ is a System z® hardware feature that provides high performance internal communications between LPARs within the same central processor complex (CPC) without the use of any additional or external hardware equipment (for example, channel adapters, LANs, and so on).

If the host processor supports HiperSockets and Communications Server is properly configured, Communications Server will attempt to create XCF connectivity between LPARs in the same CPC using a HiperSockets link or interface. When the HiperSockets link or interface cannot be activated, TCP/IP creates a normal XCF link or interface. However, if the HiperSockets link or interface is successfully activated, but is then later stopped, TCP/IP does not create an XCF link or interface.

The HiperSockets for DYNAMICXCF device and link or interface are dynamically built and the device or interface is started during TCP/IP DYNAMICXCF stack initialization. The HiperSockets for DYNAMICXCF device and link and interface cannot be configured. The generated device name is IUTIQDIO. The generated IPv4 link name is IQDIOLNKnnnnnnnn, where nnnnnnnn is the character representation of the hexadecimal version of the DYNAMICXCF IP address. The generated IPv6 interface name is IQDIOINTF6. In general, where an XCF link or interface would normally have been used (for intra-CPC), a HiperSockets link or interface will be used.

Similar to IUTSAMEH, VTAM® will dynamically build the TRLE for IUTIQDIO when the IUTIQDIO device is started. The TRLE statement is not configured (defined) by the user.

Although HiperSockets for DYNAMICXCF is not configured with TCP/IP DEVICE and LINK or INTERFACE statements, and the TRLE is not defined by the user, the following steps must be taken to define the HiperSockets subchannel devices and IQD CHPID:

1. Using HCD or IOCP, the system administrator must define (create the IOCDS) the HiperSockets IQD CHPID (channel path ID) and subchannel devices to the applicable LPARs. To dynamically build the HiperSockets TRLE, VTAM requires a minimum of 3 subchannel devices configured with each IQD CHPID within HCD. The maximum number of subchannel devices that VTAM will use (associate with each TRLE or MPC group) is 10. For additional details regarding configuring the HiperSockets subchannel devices and IQD CHPID, see z/OS HCD Planning and Using HCD.
2. When more than one IQD CHPID is configured to a specific LPAR, VTAM start option IQDCHPID must be used to specify which specific IQD CHPID this LPAR should use. The VTAM start option controls which IQD CHPID (and related subchannel devices) VTAM selects to include in the HiperSockets MPC group (IUTIQDIO) when it is dynamically built for HiperSockets for DYNAMICXCF connectivity. Start option IQDCHPID controls the VTAM IQD CHPID selection for the HiperSockets for DYNAMICXCF device IUTIQDIO (MPC group) only. It does not control IQD CHPID selection for a user defined HiperSockets device (MPCIPA). However, a user defined HiperSockets device (IQD CHPID) cannot use (conflict with) the same IQD CHPID that the HiperSockets for DYNAMICXCF device is currently using.

   For example, if IQD CHPID 'FE'x is in use by DYNAMICXCF because of one of the following conditions, then an attempt to configure and start a user defined HiperSockets device IUTIQDFE is not allowed (IQD CHPIDs conflict):

   1. VTAM start option IQDCHPID=FE is specified
   2. VTAM start option IQDCHPID=ANY is specified, but the HiperSockets for DYNAMICXCF device IUTIQDIO is using the 'FE' CHPID
   This option can also be modified with a VTAM modify command. In most cases, the default setting will be sufficient. For additional details regarding this start option, see z/OS Communications Server: SNA Resource Definition Reference.

For additional details regarding HiperSockets, see HiperSockets concepts and connectivity.