Working with HiperSockets Converged Interfaces

Red Hat Enterprise Linux 8.6 LPAR mode

Using HiperSockets Converged Interface (HSCI) connections, a HiperSockets network interface can be combined with an external OSA- or RoCE port, thus creating a single network interface.

About this task

The HSCI function is available as of IBM z15™ or IBM® LinuxONE III.

With this function, you can connect an instance of Linux that runs in LPAR mode to z/OS through layer 2 HiperSockets. The z/OS version must support HSCI.

A converged network can span multiple IBM Z servers.

Example: Consolidating subnets

Between LPARs, you can connect Linux instances through HiperSockets. To connect to an external network, you need an OSA-Express adapter in QDIO mode, or a RoCE Express adapter.

To connect Linux and z/OS LPARs with each other and an external network, you can use OSA Express adapters, for example, as shown in Figure 1. All traffic between the operating system instances go through the OSA adapters, which puts load on the OSA adapters, and might not perform as well as HiperSockets.
Figure 1. A network using OSA Express adapters that connects Linux and z/OS LPARS
This graphic is described in the text before it.

You might add a no-charge HiperSockets for the internal communication, which allows for faster communication inside the hardware system, and reduces load on the OSA adapters.

The performance gain comes at the cost of managing twice the number of interfaces and a second IP subnet.

Communication networks at enterprise level can easily grow in complexity and become a burden for the network administrator, as shown in Figure 2
Figure 2. A complex network with two subnets and two IP addresses for each operating system instance
This graphic is described in the text that follows it.

With HSCI interfaces, you can create a converged network that includes both direct HiperSockets connections for traffic within the server hardware and external connectivity through OSA Express or RoCE Express adapters. The HSCI interface is managed as a single interface.

In the sample network, there is now only one subnet, one IP address per operating system instance, and HiperSockets is still used for fast internal communication. This setup is shown in Figure 3.
Figure 3. A converged HSCI network with one subnet and one IP address for each operating system instance
This graphic is described in the text that follows it.
All HiperSockets interfaces of the HiperSockets channel must participate in the HSCI network. A HiperSockets interface on its own cannot communicate correctly with its network neighbors.