IBM United States Software Announcement
210-008
IBM is a registered trademark of International Business Machines Corporation
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• z/OS Communications Server provides local and path MTU discovery to learn the
correct MTU size for Enterprise Extender (EE) connections. The MTU size is used
to modify the link size for EE connections. In z/OS V1.12, the link size is planned
to be updated at the RTP pipe endpoints in addition to the EE endpoints when the
MTU size changes.
• z/OS Communications Server packet trace filtering is planned to be enhanced to
support:
– Including the next hop IP address on the trace output. This can be obtained
from the fully formatted packet trace using IPCS. The next hop IP address is
also available to applications that consume the real-time packet trace through
the real-time TCP/IP networking monitoring API.
– Making packet trace filtering available to encapsulated packets that are used in
VIPAROUTE traffic.
• z/OS Communications Server is planned to provide the option to check the health
of an Enterprise Extender (EE) connection during the activation of the connection.
The health of active connections can also be verified.
• z/OS Communications Server is planned to reduce CPU utilization for TCP/IP
Callable Network Management Interface (NMI), EZBNMIFR, GetConnectionDetail.
All the filters that are specified for the request must contain the complete
identification (4-tuple) of established TCP connections. The 4-tuple of a TCP
connection consists of the local IP address, local port, remote IP address, and
remote port for the connection.
• The z/OS Communications Server Netstat function is planned to provide support
for verifying that message catalogs being used are at the correct level when they
are opened. This function is intended to prevent Netstat from abending or not
functioning correctly when the message catalog is out of synch with the Netstat
program.
• z/OS Communications Server enhances TCP/IP data tracing (DATTRACE) to
provide two new trace records:
– A Start record with State field "API Data Flow Starts" that indicates the first
data sent or received by the application for the associated TCP or UDP socket
– An End record with State field "API Data Flow Ends" that indicates the socket
has been closed
• z/OS Communications Server is designed to support RFC3484 by providing a
configurable policy table for default address selection for IPv6. The source address
selection algorithm and destination address selection algorithm are planned to
be enhanced to support additional address selection rules in conjunction with the
configured or default policy table. For example, you might choose to prefer IPv4
communication over IPv6 by providing a custom policy table for default address
selection.
• z/OS Communications Server is also planned to support RFC5014 by providing
IPv6 socket API for source address selection. Applications can indicate they prefer
temporary IPv6 addresses over public IPv6 addresses or public IPv6 addresses
over temporary IPv6 addresses.
• Additionally, z/OS Communications Server is planned to enhance the SRCIP
configuration to allow an administrator to indicate that the TCP/IP stack should
prefer public IPv6 addresses over temporary IPv6 addresses. This will allow you to
override the preferences specified by an application using the IPv6 socket API for
source address selection.
• z/OS Communications Server is planned to allow the system resolver to
send requests to Domain Name System (DNS) name servers using IPv6
communication. This function is planned to allow you to use the existing
NSINTERADDR and NAMESERVER resolver configuration statements in the
TCPIP.DATA dataset to define the IPv6 address of the name server.
• z/OS Communications Server allows the coding of MULTIPATH in the TCP/IP profile
that enables multipath support for IP packets. You might want this behavior
for TCP connections but not for Enterprise Extender (EE) connections. In z/OS
Communications Server V1.12, the multipath function is planned to be disabled by
default for EE connections regardless of the value specified in the TCP/IP profile.
You can use the VTAM start option MULTPATH to control the multipath function for
EE.
