Concepts and considerations for the IQD CHPID

The HiperSockets™ hardware device is represented by the IQD CHPID and its associated subchannel devices. All LPARs that are configured (HCD) to use the same IQD CHPID have internal connectivity and therefore have the capability to communicate using HiperSockets. If the system supports multiple channel subsystems, and if HiperSockets connectivity is required across multiple channel subsystems, the IQD CHPID must also be configured (HCD) to span the applicable channel subsystems. The IQD CHPID can be viewed as a logical LAN within the CPC. The HiperSockets hardware allows up to four (16 with systems that support multiple channel subsystems) separate IQD CHPIDs to be defined per CPC, creating the capability of having four (16 with systems that support multiple channel subsystems) separate logical LANs within the same CPC. Figure 1 and Figure 2 illustrate this concept:

Figure 1. HiperSockets internal LAN

Figure 2. HiperSockets multiple internal LANs

HiperSockets with multiple IQD CHPIDs demonstrating logical network isolation

With this capability, the system administrator can logically separate (or control) the internal connectivity. This is accomplished by controlling which specific LPARs are allowed to internally connect using HiperSockets. Further examples of this are as follows:

SYSPLEX 'A' LPARs running on LPs 1 through 4 could use IQD CHPID x'FC'.
SYSPLEX 'B' LPARs running on LPs 5 through 8 could use IQD CHPID x'FD'.
A VM LPAR runs in LP 9 running various second level systems (Linux and z/OS®) which use IQD CHPID x'FE'.
Combinations of these examples could be:
- Another set of LPARs on LPs 10 through 12 which are not using DYNAMICXCF (non SYSPLEX) are connected to IQD CHPIDs x'FE' and x'FF'.
- Subsets of LPARs 1 through 8 are using both the DYNAMICXCF IQD CHPIDs and a non-DYNAMICXCF IQD CHPIDs.
- Some LPARs are connected to all four IQD CHPIDs.

In a HiperSockets CHPID, IP addresses of the HiperSockets interfaces can be in the same subnet or in different subnets. Some applications can detect when HiperSockets IP addresses are in different logical subnets and might issue warning or error messages. For further subdivision of connectivity in the HiperSockets CHPID using virtual LANs, see HiperSockets and VLAN.