## D.3.6 Planning considerations 

In the z/OS SMC-D implementation, z/OS uses a single VF per ISM PNet. This configuration is true for a single VLAN or for multiple VLANs per PNet. The number of VLANs that are defined for a specific PNet does not affect the number of VFs required. 

z/OS Communications Server requires one ISM FID per ISM PNet ID per TCP/IP stack. This requirement is not affected by the version of the IP (that is, it is true even if both IPv4 and IPv6 are used). 

z/OS might use more ISM FIDs for the following reasons: 

GLYPH<SM590000> IBM supports up to eight TCP/IP stacks per z/OS LPAR. SMC-D can use up to eight FIDs or VFs (one per TCP/IP stack). 

GLYPH<SM590000> IBM supports up to 32 ISM PNet IDs per CEC. Each TCP/IP stack can have access to PNet ID that uses up to 32 FIDs (one VF per PNet ID). 

## D.3.7 Hardware configuration definitions 

Complete the following steps to use HCDs: 

1. Configure ISM vPCI Functions (HCD/HCM). 

2. Define PNet IDs (OSA, HiperSockets [IQD], and ISM) in HCD/HCM. 

3. Activate the definition by using HCD. 

4. Enable SMC-D in at least two z/OS instances, which are a single parameter in TCP/IP Global configuration. Both z/OS instances must run on the same CPC. 

5. Review and adjust as needed the available real memory and fixed memory usage limits (z/OS and CS). SMC requires fixed memory. You might need to review the limits and provision more real memory for z/OS. 

6. Review the IP topology, VLAN usage considerations, and IP security. For more information, see the  IBM z/OS Shared Memory Communications: Security Considerations white paper. 

7. Run Shared Memory Communications Applicability Tool (SMC-AT) to evaluate applicability and potential value. 

8. Review changes to messages, monitoring information, and diagnostic tools. Similar to SMC-R, many updates are made to the following items: 

– Messages (VTAM and TCP stack) 

– Netstat (status, monitoring, and display information) 

– CS diagnostic tools (VIT, Packet trace, CTRACE, and IPCS formatted dumps) 

Note:  No application changes (transparent to Socket applications) are made. Also, no optional operation changes are required (for example starting or stopping devices). 

ISM Functions must be associated with another channel (CHID) of one of the following types: 

GLYPH<SM590000> IQD (a single IQD HiperSockets) channel 

GLYPH<SM590000> OSD channels 

Note:  A single ISM PCHID cannot be associated with both IQD and OSD. 

