Modifying HiperSockets connectivity [TCP/IP device and link and the VTAM HiperSockets MPC group (IUTIQDIO)]
Certain modifications can be made to the HiperSockets™ device (MPC group) without disrupting an active TCP/IP stack.
z/OS® supports dynamic I/O for the HiperSockets CHPID and subchannel devices, allowing subchannel devices to be added or removed to or from an LPAR which has already been IPLed.
TCP/IP supports the STOP and START command for the DYNAMICXCF HiperSockets device (IUTIQDIO). However, the commands are supported only when the (internal) start (activation) was successful during stack initialization. TCP/IP also supports the STOP and START command for the user-defined HiperSockets devices (IUTIQDxx). Because a user-defined HiperSockets device is supported as an MPCIPA device, STOP and START function just as they would for other MPCIPA devices.
VTAM® supports a MODIFY VTAMOPTS command that you can use to change the initial setting of the IQDCHPID start option.
- Alter which specific IQD CHPID is used for DYNAMICXCF (for example, move from the x'FC' CHPID to the x'FD' CHPID).
- Add or remove subchannel devices (for example, from the current IQD CHPID).
- Alter the IQD MFS which alters the TCP/IP MTU (for example, increase the current IQD CHPID from 16k to 64k).
- When MODIFIED from ANY (or CHPID) to NONE, there is no effect on current usage but blocks subsequent activations of the DYNAMICXCF HiperSockets device.
- When MODIFIED from NONE to ANY (or CHPID), there is no effect on current usage but allows subsequent activations.
- When MODIFIED from CHPID_X to CHPID_Y, there is no effect on current
usage. Note: VTAM uses the CHPID value only when building the IUTIQDIO MPC group.To change CHPIDs for an active MPC group, take the following steps:
- TCP/IP IUTIQDIO devices and IQDIOINTF6 interfaces that are changing must be stopped.
- Make any necessary HCD/IOCDS changes.
- Verify new subchannel devices are varied online.
- Verify the MPC group has deactivated (with no usage it times out after approximately 2 minutes).
- Modify IQDCHPID = CHPID (to new CHPID).
- Restart the TCP/IP IUTIQDIO devices and IQDIOINTF6 interfaces.