D.3.3 Internal Shared Memory - Introduction - IBM z13s Technical Manual

– Preservation of the existing IP security model, such as IP filters, policies, VLANs,
and SSL
– Minimal network administration and management changes
Host application software is not required to change, so all host application workloads can
benefit immediately.

D.3.3 Internal Shared Memory - Introduction

The IBM z13 (Driver 27) and z13s servers introduce the ISM virtual PCI function. ISM is a
virtual PCI network adapter that enables direct access to shared virtual memory providing a
highly optimized network interconnect for z Systems intra-CPC communications. ISM
introduces a new static virtual channel identifier (VCHID) Type. The VCHID is referenced in
IOCDS / HCD. The ISM VCHID concepts are similar to the IQD (HiperSockets) type of virtual
adapters. ISM is based on existing z Systems PCIe architecture (that is virtual PCI function /
adapter). It introduces a new PCI Function Group and type (ISM virtual PCI). There will be a
new virtual adapter.
The system admin, configuration, and operations tasks follow the same process
(HCD/IOCDS) as existing PCI functions such as RoCE Express, zEDC Express, and so on.
ISM supports dynamic I/O.
ISM Provides adapter virtualization (Virtual Functions) with high scalability:
It supports up to 32 ISM VCHIDs per CPC (z13 or z13s servers, each VCHID represents a
unique internal shared memory network each with a unique Physical Network ID)
Each VCHID supports up to 255 VFs per VCHID (the maximum is 8k VFs per z13 or z13s
CPC), which provide significant scalability.
Note: There is no concept of a PCI Physical Function to provide virtualization. There is
no concept of MACs, or MTU or Frame size.
– Each ISM VCHID represents a unique and isolated internal network, each having a
unique Physical Network ID (PNet IDs are configured in HCD/IOCDS).
ISM VCHIDs support VLANs, so subdividing a VCHID using virtual LANs is supported.
ISM provides a Global Identifier (GID) that is internally generated to correspond with each
ISM FID.
ISM is supported by z/VM in pass-through mode (PTF required).
D.3.4 Virtual PCI Function (vPCI Adapter)
Virtual Function ID is defined when PCIe hardware is shared between LPARs. Virtual
Function ID has a decimal Virtual Function Identifier (VF=) in the range 1 – n, where n is the
maximum number of partitions the PCIe feature supports. For example, the SMC-D ISM
feature supports up to 32 partitions, and a zEDC Express feature supports up to 15.
The following basic infrastructure is available:
zPCI architecture
RoCE, zEDC, ISM
zPCI layer in z/OS and Linux for z Systems
vPCI for SD queues
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IBM z13s Technical Guide