Description: z/OS® V2R1
Communications Server includes the following enhancements for economics
and platform efficiency:
- QDIO acceleration coexistence with IP filtering - The QDIO
Accelerator function, which provides accelerated forwarding of packets,
is enabled when IP Security is enabled. In previous releases, QDIO
Accelerator could not be enabled if IP Security was enabled.
- TCP support for selective acknowledgments - The following
TCP support for selective acknowledgments is provided:
- Generation of TCP selective acknowledgments as defined in RFC
2018
- Exploitation of incoming TCP selective acknowledgments to improve
TCP retransmission processing as defined in RFC 3517
A TCP connection might experience poor performance when multiple
packets are lost from one window of data. With the limited information
available from cumulative acknowledgments, a TCP sender can learn
about only a single lost packet per round-trip time. A Selective Acknowledgment
(SACK) mechanism, combined with a selective repeat retransmission
policy, can help to overcome these limitations. The receiving TCP
sends back SACK packets to the sender informing the sender of data
that has been received. The sending TCP can then retransmit only the
missing data segments.
- Shared Memory Communications over Remote Direct Memory Access -
Significant performance improvements for TCP protocol workloads on
external networks are provided. This solution uses Shared Memory Communications
over Remote Direct Memory Access (SMC-R) for TCP connections to remote
peers on external networks that also support this function.
- Shared Memory Communications over RDMA Enhancements -
The amount of 64-bit storage that is allocated can now be displayed
by using the D NET,BFRUSE command.
- Shared Memory Communications over RDMA adapter (RoCE)
virtualization - The Shared Memory Communications over Remote
Direct Memory Access (SMC-R) function is extended to allow TCP/IP
stacks on different LPARs within the same central processor complex
(CPC) to share the same physical IBM 10GbE RoCE Express feature.
- Connection termination notification for sockets - An application
can issue a synchronous or an asynchronous receive socket API call
that completes only when a TCP connection is ended.
This support
is available on the recv(), recvfrom(), and recvmsg() functions in
the z/OS XL C/C++ Runtime Library.
The support is also available on the recv(BPX1RCV, BPX4RCV), recvfrom(BPX1RFM,
BPX4RFM), recvmsg(BPX2RMS, BPX4RMS), and asyncio(BPX1AIO, BPX4AIO)
assembler callable services.
- IPv6 support for policy-based routing - With IPv6 policy-based
routing, the TCP/IP stack can make IPv6 routing decisions that take
into account criteria other than just the destination IP address.
The additional criteria can include job name, source port, destination
port, protocol type (TCP or UDP), source IP address, NetAccess security
zone, and security label.
- Affinity for application-instance DVIPAs - The support
to create a VIPARANGE DVIPA is provided with affinity to the address
space of the application that created it. In previous releases, the
SIOCSVIPA and SIOCSVIPA6 IOCTL functions and the MODDVIPA utility
supported the define and delete options. In z/OS V2R1 Communications Server, a new define
with affinity option is supported. When an application uses the SIOCSVIPA
or the SIOCSVIPA6 IOCTL function to create a DVIPA with the address
space affinity option, connection requests for this DVIPA are routed
to a server that runs in the address space of the application. This
behavior is beneficial when there are multiple shareport applications
listening on the IPv4 inaddr_any or the IPv6-unspecified address.
With this new support, the application that created the DVIPA is preferred
over other listeners. If no matching listeners are available, normal
shareport load balancing is used to select the best available listener.
- Enhanced Fast Path socket support - The performance of
the following 6 API calls is enhanced: recv()/send(), recvfrom()/sendto(),
and recvmsg()/sendmsg(). This function is automatically enabled; no
tasks are necessary.
- Enhanced TCP protocol configuration options and default settings -
The TCP configuration options have the following changes:
- New parameters on the TCPCONFIG statement
- Changes to the default values and limits of existing parameters
on the TCPCONFIG and SOMAXCONN statements
When change was introduced: z/OS V2R1