Shared Memory Communications - Direct multiple IP subnet support (SMC-Dv2)

z/OS® V2R4 Communications Server, with TCP/IP APAR PH22695 and SNA APAR OA59152, Shared Memory Communication - Direct Memory Access (SMC-D) is enhanced to remove the same subnet restriction by exploiting SMC-Dv2.

Dependencies:

SMC-Dv2 is enabled with new IBM Z capability provided by the IBM Z Internal Shared Memory (ISM) function. The new ISMv2 capability is available on IBM z15. For IBM z15 T01, refer to the MCL number P46601.067 driver D41C. The ISMv2 support is in the base of the IBM z15 T02.

Downlevel SMC partners might require a toleration PTF. If you plan to enable SMC-Dv2 on a host which has connections to a down-level SMC (SMC-Dv1 or SMC-Rv1) system (z/OS Communications Server, Linux on Z, and AIX), the down-level host will require the following toleration maintenance applied prior to enabling SMC-Dv2:

For z/OS Communications Server, the down-level host will need the appropriate PTF for PH17556.
For Linux on Z, see the Linux on Z web page at https://linux-on-z.blogspot.com/p/smc-for-linux-on-ibm-z.html for information related to toleration requirements.
For AIX, see the AIX web page at https://www.ibm.com/support/knowledgecenter/en/ssw_aix_72/rdma/smc_r.html for information related to toleration requirements.

Note: Failure to apply the proper toleration maintenance might result in connection hangs or failures when SMC-Dv2 is enabled on z/OS.

The PTF for z/OS IOS PCIe Services APAR OA59235 is required. Failure to apply that PTF will result in activation failures.

Using the Shared Memory Communications - Direct multiple IP subnet support (SMC-Dv2)

To use the Shared Memory Communications - Direct multiple IP subnet support (SMC-Dv2), perform the tasks in Table 1.

Table 1. Shared Memory Communications - Direct multiple IP subnet support (SMC-Dv2)
Task/Procedure	Reference
Determine if using SMC will be a benefit in this configuration by using SMCAT.	VARY TCPIP,,SMCAT about SMC Applicability Tool (SMCAT) in z/OS Communications Server: IP System Administrator's Commands
Configure SMCEID on the SMCGLOBAL parameter of the GLOBALCONFIG statement to enable z/OS CS exploitation of SMC-Dv2.	GLOBALCONFIG statement in z/OS Communications Server: IP Configuration Reference
Configure SYSTEMEID on the SMCD parameter of the GLOBALCONFIG statement to enable z/OS CS exploitation of SMC-Dv2.	GLOBALCONFIG statement in z/OS Communications Server: IP Configuration Reference
Display whether SMCEID values were specified on SMCGLOBAL by issuing the Netstat CONFIG/-f command.	Netstat CONFIG/-f report in z/OS Communications Server: IP System Administrator's Commands
Display SMC version used for a connection or link.	z/OS Communications Server: IP System Administrator's Commands: Netstat ALL/-A report Netstat DEvlinks/-d report
Display all interfaces z/OS CS used for SMC communications.	Netstat DEvlinks/-d report in z/OS Communications Server: IP System Administrator's Commands
Display information about the dynamic ISM TRLEs by issuing the D NET,ID=`trle`, or D NET,TRL,TRLE=`trle` command, which might now show NA for the PNETID.	z/OS Communications Server: SNA Operation DISPLAY ID command DISPLAY TRL command

To find all new and updated topics about Shared Memory Communications - Direct multiple IP subnet support (SMC-Dv2), see .

Table 2. All related topics about Shared Memory Communications - Direct multiple IP subnet support (SMC-Dv2)
Book name	Topics
z/OS Communications Server: IP Configuration Guide	Shared Memory Communications - Direct Multiple IP Subnet Support (SMC-Dv2) Physical network considerations VLANID considerations Configuring Shared Memory Communications - Direct Memory Access
z/OS Communications Server: IP Configuration Reference	GLOBALCONFIG statement
z/OS Communications Server: IP Programmer's Guide and Reference	TCP connection termination record (subtype 2) SMC-D link statistics record (subtype 38) SMC-D link state start record (subtype 39) SMC-D link state end record (subtype 40) TCP/IP profile record Global configuration section
z/OS Communications Server: IP Diagnosis Guide	Diagnosing problems with Shared Memory Communications Physical network ID configuration issues No associated subnet mask
z/OS Communications Server: IP System Administrator's Commands	DISPLAY TCPIP,,NETSTAT VARY TCPIP,,SMCAT Netstat ALL/-A report Netstat CONFIG/-f report Netstat DEvlinks/-d report
z/OS Communications Server: SNA Operation	DISPLAY ID command DISPLAY TRL command
z/OS Communications Server: SNA Diagnosis Vol 2, FFST Dumps and the VIT	ENFx entry for ENF exit RPLA entry for invoking a RoCE Poll command (Part 3)
z/OS Communications Server: IP Messages Volume 2 (EZB, EZD)	EZD2051I
z/OS Communications Server: SNA Messages	IST2418I IST2421I IST2464I IST2465I