HiperSockets

The HiperSockets function, also known as internal Queued Direct Input/Output (iDQIO) or internal QDIO, is an inte- grated function of the z10 EC server that provides users with attachments to up to sixteen high-speed “virtual” Local Area Networks (LANs) with minimal system and network overhead. HiperSockets eliminates the need to utilize I/O subsystem operations and the need to traverse an external network connection to communicate between logical partitions in the same z10 EC server.

Now, the HiperSockets internal networks on z10 EC can support two transport modes: Layer 2 (Link Layer) as well as the current Layer 3 (Network or IP Layer). Trafﬁ c can be Internet Protocol (IP) version 4 or version 6 (IPv4, IPv6) or non-IP (AppleTalk, DECnet, IPX, NetBIOS, or SNA). HiperSockets devices are now protocol-independent and Layer 3 independent. Each HiperSockets device has its own Layer 2 Media Access Control (MAC) address, which is designed to allow the use of applications that depend on the existence of Layer 2 addresses such as DHCP servers and ﬁ rewalls.

Layer 2 support can help facilitate server consolidation. Complexity can be reduced, network conﬁ guration is simpliﬁ ed and intuitive, and LAN administrators can con-

ﬁgure and maintain the mainframe environment the same as they do a non-mainframe environment. With support of the new Layer 2 interface by HiperSockets, packet forwarding decisions are now based upon Layer 2 infor- mation, instead of Layer 3 information. The HiperSockets device performs automatic MAC address generation and assignment to allow uniqueness within and across logical partitions (LPs) and servers. MAC addresses can also be locally administered. The use of Group MAC addresses for multicast is supported as well as broadcasts to all other Layer 2 devices on the same HiperSockets network. Datagrams are only delivered between HiperSockets devices that are using the same transport mode (Layer 2

with Layer 2 and Layer 3 with Layer 3). A Layer 2 device cannot communicate directly with a Layer 3 device in another LPAR.

A HiperSockets device can ﬁ lter inbound datagrams by Virtual Local Area Network identiﬁ cation (VLAN ID, IEEE 802.1q), the Ethernet destination MAC address, or both. Filtering can help reduce the amount of inbound traf-

ﬁc being processed by the operating system, helping to reduce CPU utilization.

Analogous to the respective Layer 3 functions, HiperSockets Layer 2 devices can be conﬁ gured as primary or secondary connectors or multicast routers. This is designed to enable the creation of high performance and high availability Link Layer switches between the internal HiperSockets network and an external Ethernet or to connect the HiperSockets Layer 2 networks of different servers. The HiperSockets Multiple Write Facility for z10 EC is also supported for Layer 2 HiperSockets devices, thus allowing performance improvements for large Layer 2 datastreams.

HiperSockets Layer 2 support is exclusive to System z10 and is supported by z/OS, Linux on System z environ- ments, and z/VM for Linux guest exploitation.

HiperSockets Multiple Write Facility for increased performance

Though HiperSockets provides high-speed internal TCP/IP connectivity between logical partitions within a System z server – the problem is that HiperSockets draws excessive CPU utilization for large outbound messages. This may lead to increased software licensing cost – HiperSock- ets large outbound messages are charged to a general CPU which can incur high general purpose CPU costs. This may also lead to some performance issues due to synchronous application blocking – HiperSockets large outbound messages will block a sending application while synchronously moving data.