Networking

Networking Enhancements for IBM System z

OSA/SF now available on the HMC: OSA Advanced Facilities on the Hardware Management Console (HMC) has been enhanced to provide configuration, validation, activation, and display support exclusively for the OSA-Express5S and OSA-Express4S features. For these features, the Advanced Facilities function on the HMC is used instead of the Open Systems Adapter Support Facility (OSA/SF) - a component of z/OS, z/VM, and z/VSE.

OSA/SF on the HMC is exclusive to the zEC12 and zBC12. The latest driver level is required.

OSA/SF on the HMC can be used to configure channel path identifier (CHPID) type OSE. It can be used to manage (query/display) CHPID types OSD, OSE, and OSN. Refer to the document, OSA/SF on the Hardware Management Console, SC14-7580, which can be found in the Library section of Resource Link September 20, 2013:
www.ibm.com/servers/resourcelink

Query and display OSA configuration (Display OSAINFO) – for network management: Previously, the OSA-Express system architecture introduced the capability for operating systems to dynamically register the Open Systems Adapter (OSA) configuration. This approach significantly improved the OSA-Express usability by reducing the burden placed on the system administrator to manually configure OSA-Express for each unique operating system configuration. Traditionally, the Open Systems Adapter Support Facility (OSA/SF) has provided the administrator with the ability to monitor the OSA configuration.

As additional complex functions have been added to OSA, the ability for the system administrator to display, monitor, and verify the specific current OSA configuration unique to each operating system has become more complex.

The OSA-Express5S, OSA-Express4S, and OSA-Express3 features support the capability for the operating system to directly query and display the current OSA configuration information (similar to OSA/SF). z/OS exploits this OSA capability with the introduction of a TCP/IP operator command called Display OSAINFO. Display OSAINFO allows the operator to monitor and verify the current OSA configuration, which helps to improve the overall management, serviceability, and usability of an OSA-Express5S, OSA-Express4S, or OSA-Express3 feature.

Display OSAINFO is supported by the OSA-Express5S, OSA-Express4S, and OSA-Express3 features for CHPID types OSD, OSM, and OSX, and to the z/OS operating system and z/VM for guest exploitation. CHPID types OSM and OSX are exclusive to zEC12, zBC12, z196, and z114 servers. The zEC12, zBC12, z196, and z114 servers support this function.

Checksum offload for IPv6 packets is available for z/OS environments and for z/VM guest exploitation: When the checksum function is offloaded from the host, CPU cycles are reduced, improving performance. Using OSA-Express5S or OSA-Express4S, the checksum offload function is performed for IPv6 packets as well as IPv4 packets, whether the traffic goes out to the local area network (LAN), comes in from the LAN, or flows logical partition-to-logical partition through an OSA-Express5S or OSA-Express4S feature.

Checksum offload provides the capability of calculating the Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Protocol (IP) header checksums for Internet Protocol Version 4 (IPv4) packets and IPv6 packets.

When checksum offload was introduced in May of 2003, it was limited to IPv4 packets. Checksum offload for IPv6 packets is exclusive to OSA-Express5S and OSA-Express4S features (CHPID types OSD and OSX). It is supported by z/OS and by z/VM for guest exploitation. Checksum offload for IPv4 packets is currently available for all in-service releases of z/OS and Linux on System z. The zEC12, zBC12, z196, and z114 servers support this function.

Checksum offload for LPAR-to-LPAR traffic in the z/OS environment is included in the OSA-Express5S and OSA-Express4S design for both IPv4 and IPv6 packets.

Large send for IPv6 packets is now available for z/OS environments: Large send (also referred to as TCP segmentation offload) is designed to improve performance by offloading outbound TCP segmentation processing from the host to an OSA-Express5S or OSA-Express4S feature by employing a more efficient memory transfer into the feature.

Large send support for IPv6 packets applies to the OSA-Express5S and OSA-Express4S features (CHPID type OSD and OSX), It is supported by z/OS. Large send for IPv4 packets is currently available for all in service releases of z/OS and Linux on System z, and z/VM for guest exploitation. The zEC12, zBC12, z196, and z114 servers support this function.

Note: Large send is not supported for LPAR-to-LPAR packets.

OSA-Express5S and OSA-Express4S 10 Gigabit Ethernet performance for inbound traffic:

OSA-Express5S performance is comparable to OSA-Express4S. The results documented here were measured using OSA-Express4S.

Performance using jumbo frames: In laboratory measurements, using an OSA-Express4S 10 Gigabit Ethernet (10 GbE) feature in a z196 defined as CHPID type OSD with an inbound-to-the-host streams workload operating at 10 Gbps, we achieved a maximum user-payload throughput of 1,180 megabytes per second (MBps) compared to a maximum of 680 MBps achieved with an OSA-Express3 10 GbE feature on a z196. This represents approximately a 70% increase for jumbo frames (8000 byte frames).

Measurements with mixed-direction streams workload in the same jumbo frames environment, with an OSA-Express4S 10 GbE feature, we achieved a maximum user-payload throughput of 2,080 MBps with an OSA-Express4S 10 GbE feature compared to a maximum of 1,240 MBps on an OSA-Express3 10 GbE feature on z 196. This represents approximately a 70% increase for jumbo frames.

Performance using standard frames: In laboratory measurements, using an OSA-Express4S 10 GbE feature in a z196 defined as CHPID type OSD with an inbound-to-the-host streams workload operating at 10 Gbps, we achieved a maximum user-payload throughput of 1,120 MBps compared to a maximum of 615 MBps achieved with an OSA-Express3 10 GbE feature on a z196. This represents approximately an 80% increase for standard frames (1492 byte frames).

Measurements with a mixed-direction streams workload in the same standard frames environment, with an OSA-Express4S 10 GbE feature, we achieved a maximum user-payload throughput of 1,680 MBps with an OSA-Express4S 10 GbE compared to a maximum of 1,180 MBps with an OSA-Express3 10 GbE feature on a z196. This represents approximately a 40% increase for standard frames.

OSA-Express4S 10 GbE performance was measured in a controlled environment using IBM Application Workload Modeler (AWM). The actual throughput or performance that any user may experience will vary depending upon considerations such as the amount of multiprogramming in the user's job stream, the network options and configuration, and the workload processed. One MBps represents 1,048,576 bytes per second.

Access AWM information at http://www.ibm.com/software/network/awm/index.html

OSA-Expresss5S and OSA-Express4S Gigabit Ethernet are already capable of line speed for jumbo frames and standard frames.

Inbound Workload Queuing for Enterprise Extender - for improved scalability and performance: Inbound workload queuing (IWQ) for the OSA-Express features was enhanced to differentiate and separate inbound Enterprise Extender traffic to a new input queue. The Enterprise Extender separation and processing associated with the Enterprise Extender input queue provides improved scalability and performance for Enterprise Extender.

With each input queue representing a unique type of workload, each having unique service and processing requirements, the IWQ function allows z/OS to use appropriate processing resources for each input queue. This approach allows multiple concurrent z/OS processing threads to process each unique input queue to avoid traditional resource contention. In a heavily mixed workload environment, this "off the wire" network traffic separation provided by OSA-Express IWQ reduces the conventional z/OS processing required to identify and separate unique workloads.

Inbound workload queuing for Enterprise Extender is supported by the OSA-Express5S, OSA-Express4S, and OSA-Express3 features when defined as CHPID types OSD or OSX. It is supported by z/OS and by z/VM for guest exploitation. The zEC12, zBC12, z196, and z114 servers support this function.

Inbound workload queuing – for network performance: z/OS workloads have become more diverse; each type of workload may have unique service level requirements. The OSA-Express5S, OSA-Express4S, and OSA-Express-3 features support inbound workload queuing (IWQ), which creates multiple input queues and allows OSA to differentiate workloads "off the wire" and then assign work to a specific input queue (per device) to z/OS. With each input queue representing a unique type of workload, each having unique service and processing requirements, the IWQ function allows z/OS to preassign the appropriate processing resources for each input queue. This approach allows multiple concurrent z/OS processing threads to then process each unique input queue (workload), avoiding traditional resource contention. In a heavily mixed workload environment, this "off the wire" network traffic separation provided by an OSA-Express5S, OSA-Express4S, or OSA-Express3 feature IWQ is designed to reduce the conventional z/OS processing required to identify and separate unique workloads, which results in improved overall system performance and scalability.

A primary objective of IWQ is to provide improved performance for business-critical interactive workloads by reducing contention created by other types of workloads. The types of z/OS workloads that are identified and assigned to unique input queues are:

  1. z/OS Sysplex Distributor traffic - Network traffic that is associated with a distributed dynamic virtual IP address (DVIPA) is assigned a unique input queue allowing, the Sysplex Distributor traffic to be immediately distributed to the target host.
  2. z/OS bulk data traffic - Network traffic that is dynamically associated with a streaming (bulk data) TCP connection is assigned to a unique input queue allowing, the bulk data processing to be assigned the appropriate resources and isolated from critical interactive workloads.

IWQ is exclusive to OSA-Express5S, OSA-Express4S and OSA-Express3 CHPID types OSD and OSX (CHPID type OSX is exclusive to zEC12, zBC12, z196, and z114). IWQ is also supported by the z/OS operating system and by z/VM for guests. This function is supported by the zEC12, zBC12, z196, and z114 servers.

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