IBM 890 manual OSA-Express Enhancements for Linux, HiperSockets

OSA-Express Enhancements for Linux

A new function, Checksum Offl oad, offered for the new OSA-Express GbE and 1000BASE-T Ethernet features, is being introduced for the Linux on zSeries and z/OS environments. Checksum Offl oad provides the capability of calculating the Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Protocol (IP) header checksums. Checksum verifi es the correctness of

files. By moving the checksum calculations to a Gigabit or 1000BASE-T Ethernet feature, host CPU cycles are reduced and performance is improved. When checksum is offl oaded, the OSA-Express feature performs the check- sum calculations for Internet Protocol Version 4 (IPv4) packets.

Two important networking technology advancements are announced in z/VM 4.4 and Linux on z990:

•The high performance adapter interrupt handling fi rst introduced with HiperSockets is now available for OSA- Express/OSA-Express2 in QDIO mode (CHPID=IQD) and FICON Express/FICON Express2 (CHPID=FCP). This advancement provides a more effi cient technique for I/O interruptions designed to reduce path lengths and overhead in both the host operating system and in the adapter. This benefi ts OSA-Express TCP/IP support in both Linux for zSeries and z/VM.

•The z990’s support of virtual machine technology has been enhanced to include a new performance assist for virtualization of adapter interruptions. This new

z990 performance assist is available to V=V guests (pageable guests) that support QDIO on z/VM 4.4. The deployment of adapter interruptions improves effi ciency and performance by reducing z/VM Control Program overhead when handling Linux guest virtual servers.

HiperSockets

HiperSockets can be used for communication between Linux images and Linux or z/OS images, whether Linux is running in an IFL LPAR, natively or under z/VM.

Virtual Local Area Networks (VLANs), IEEE standard 802.1q, is now being offered for HiperSockets in a Linux on zSeries environment. VLANs can reduce overhead by allowing networks to be organized for optimum traffi c

flow; the network is organized by traffi c patterns rather than physical location. This enhancement permits traffi c to fl ow on a VLAN connection both over HiperSockets and between HiperSockets and an OSA-Express GbE, 1000BASE-T Ethernet, or Fast Ethernet feature.

Internet Protocol Version 4 (IPv4) broadcast packets are now supported over HiperSockets. TCP/IP applications that support IPv4 broadcast, such as OMPROUTE when running Routing Information Protocol Version 1 (RIPv1), can send and receive broadcast packets over HiperSockets interfaces. This support is exclusive to z990.

You can now transparently bridge traffi c between a HiperSockets and an external OSA-Express network attachment. New Linux Layer 2 Switch (Linux L2S) support can help simplify network addressing between HiperSockets and OSA-Express. You can now seamlessly integrate HiperSockets-connected operating systems into external networks, without requiring intervening network routing overhead, thus increasing performance and simpli- fying confi guration.

The currently available distributions; SUSE SLES 7, SUSE SLES 8, Red Hat 7.1 and Red Hat 7.2 support z990 compatibility and exploitation of 30 LPARs and 2 Logical Channel SubSystems. Support to further exploit z990 func- tions will be delivered as an Open Source Contribution

56