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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
fi les. 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
fl ow; 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