IBM z13s User Manual

Appendix D. Shared Memory Communications 491
SMC-D is a “hybrid” solution as shown in Figure D-13:
򐂰 It uses a TCP connection to establish the SMC-D connection.
򐂰 The TCP connection can be either through the OSA adapter or IQD HiperSockets
򐂰 A TCP option (SMCD) controls switching from TCP to “out of band” SMC-D.
򐂰 The SMC-D information is exchanged within the TCP data stream.
򐂰 Socket application data is exchanged through ISM (write operations).
򐂰 The TCP connection remains to control the SMC-D connection.
򐂰 This model preserves many critical existing operational and network management
features of TCP/IP.
Figure D-13 Dynamic transition from TCP to SMC-D by using two OSA-Express adapters
The hybrid model of SMC-D uses these key existing attributes:
򐂰 It follows the standard TCP/IP connection setup.
򐂰 The hybrid model switches to ISM (SMC-D) dynamically.
򐂰 The TCP connection remains active (idle) and is used to control the SMC-D connection.
򐂰 The hybrid model preserves the following critical operational and network management
TCP/IP features:
– Minimal (or zero) IP topology changes
– Compatibility with TCP connection-level load balancers
OSA
ISM
TCP
IP
Interf ace
Sockets
Middleware/Application
z/OS LPAR B
SMC-D
OSA
ISM
TCP
IP
Interf ace
Sockets
Middleware/Application
z/OS LPAR A
SMC-D
TCP connection establishment over IP
IP Network (Ethernet)
ISM VCHID (within System z)
TCP connection transitions to SMC-D allowing application data to be exchanged using Direct
Memory Access (LPAR to LPAR)
Dynamic (in-line) negotiation for SMC-R&SMC-D is initiated by presence of TCP Options
TCP syn flows (with TCP Options
CLC indicating SMC-R+SMC-D capability)
data exchanged using
native PCI operations
(PCI STB)
IBM z13 or z13s
Data exchanged using
native PCI operations
(PCI STB)
OSA and ISM
have the same
PNet ID

IBM z13s Specifications

General

Brand	IBM
Model	z13s
Category	Server
Language	English