Global Virtual Switch Overview

A Global VSwitch is a collection of VSwitches in different z/VM® systems sharing the same networking characteristics. A Global Virtual Switch provides a single point of control for Uplink Port management. This concept allows a virtual switch defined in an image of z/VM system, to be logically grouped together with other virtual switches in different z/VM Systems, into one virtual switch. Each virtual switch making up a Global VSwitch must have the same name, the same VSwitch Type, Transport Type and communicate with each other through a new Inter-VSwitch Link (IVL) network. If we look at this from a hardware perspective, this is analogous to a physical switch’s “virtual chassis” support, where multiple switches are tied together to form a single logical physical switch.

Each VSwitch comprising the global VSwitch must be able to exchange control information with each other in order to form a single logical switch. This private communication is absolutely necessary in order to join and serialize all the VSwitches into a global VSwitch. Like a virtual switch’s hardware counterpart exploiting “virtual chassis”, this private control plane is established to provide inter-z/VM system communication in both an SSI and a single system configuration.

The instantiation of a global VSwitch is performed by specifying the GLOBAL operand on the DEFINE VSWITCH Command or Configuration Statement. The GLOBAL operand is used to include a virtual switch as a member of the global VSwitch. The same virtual switch name must be assigned by a system administrator to the collection of virtual switches which share the same network characteristics as documented earlier in this section. All virtual switches defined with the GLOBAL operand and same virtual switch name are members of the global VSwitch. The eight byte VSwitch name defines a specific member within the global VSwitch.

For example: VSwitch PEGGY is a global VSwitch. The name that identifies the switch member of PEGGY on the z/VM system named CASEY is CASEY.PEGGY. Likewise the switch member that identifies PEGGY on the z/VM system named JONES is JONES.PEGGY.

Global VSwitches are the only VSwitches that can be configured with a shared port group in a LAG configuration (known as Multi-VSwitch LAG). The IVL connectivity allows all sharing global VSwitches to both manage and share the same physical LAG by exchanging LACP information, status, control, and load balancing information with each other. See Virtual Switch Link Aggregation for more information on Multi-VSwitch LAG.