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z/OS Communications Server
  What's New
What's new in z/OS V1R4 Communications Server?


z/OS Communications Server Internet Protocol Version 6 (IPv6)

IPv6 is an evolution of the current version, IP Version 4 (IPv4), and is designed to improve upon the older protocol. Most of today's Internets use IPv4, which is now approximately 20 years old and beginning to experience challenges. IPv6 improves upon IPv4 in a number of ways. For example, IPv6 uses 128-bit addresses, an address space large enough to last for the foreseeable future. It also adds many improvements to IPv4 in areas such as configuration, administration, and management.


The major benefits of IPv6 fall into the following categories:

  • Increased Scalability: IPv6 uses a 128-bit address space, which has no practical limit on global addressability and provides 340 billion billion billion unique addresses. Stated another way, this is enough addresses so that every person can have a single IPv6 network with as many as 18,000,000,000,000,000 nodes on it, and the address space would still be almost completely unused. Of all improvements provided by IPv6, this is by far the most important as it addresses the needs of a global, pervasive Internet containing several billion nodes

  • Potential to Reduce Administration Costs: The vastly greater availability of IPv6 addresses eliminates the need for private address spaces, which in turn eliminates one of the needs for network address translators (NATs) to be used between the private intranet and the public Internet. NAT administration is both complex and time consuming and may interfere with certain functions

  • Simplified Configuration: IPv6 provides improved support for plug-and-play. Stateless autoconfiguration allows a host to configure its own globally routable addresses in cooperation with a local IPv6 router, eliminating much of the manual configuration required for IPv4. IPv6 nodes are also able to automatically learn additional configuration data, such as the link MTU and which neighbor nodes may be reached without sending packets through a router. Manual configuration of interface addresses may be used in environments where complete local control of address configuration is required

  • Support for Renumbering: Hosts are automatically notified by routers of new network prefixes when a renumbering event occurs. Renumbering events may occur when a company changes ISPs, or may occur when the internal network is redesigned. For IPv6 addresses assigned using stateless autoconfiguration, a host will automatically define and begin using new IP addresses when it learns about a renumbering event. In addition, the host will delete IP addresses that were using the old prefixes

  • Application Compatibility: Unmodified applications continue to work and may communicate with partners across the IPv4 network. Enhanced socket APIs are provided that may be used to communicate with partners across either an IPv4 or an IPv6 network. In addition, with the implementation of z/OS dual-mode stack support (a dual-mode stack node is one where a single TCP/IP instance is able to connect to both an IPv4 and an IPv6 network simultaneously), a single IPv6 application can communicate with partners via either the IPv4 or IPv6 network. IPv6 support in V1.4 requires the use of an OSA-Express adapter running in QDIO mode and is supported only on OSA-Express features on zSeries at driver level 3G (GA3 code) or above. IPv6 requires a zSeries processor

Networking for Large-Scale e-business

z/OS V1.4 Communications Server e-business networking enhancements include:

  • Simple Network Time Protocol Daemon (SNTPD): z/OS V1.4 Communications Server includes SNTPD, a new TCP/IP daemon. By providing a Simple Network Time Protocol (SNTP) Server, z/OS can supply the time to the network enabling synchronization of time between a client and a server. The availability of this function answers the need of customers who have requested the ability to synchronize clocks between various platforms in their network

  • SNA Network Improvements and Enterprise Extender: A number of enhancements are provided to help reduce operational costs, simplify configuration, and improve diagnosis capability and serviceability in SNA networks, particularly those exploiting the Enterprise Extender (EE) function:
  1. The dial processing associated with activating EE connections is made more flexible by allowing for periodic automatic redial attempts in the event of initial activation failure (such as can occur if the switched major node is activated prior to full activation of the XCA major node), or failure after connection is established
  2. The output produced when displaying a Rapid Transport Protocol (RTP) connection (pipe) is enhanced to include additional information on the performance of the pipe. The new information includes statistics such as actual send rate, number of packets retransmitted, send and receive byte and packet counts, round trip time, current session count, and details of the last path switch attempt
  3. Trace processing and formatting are enhanced to provide approximate time stamps for each entry when formatting a data space VTAMâ Internal Trace

  • Sysplex-wide IPSec security associations and source VIPA address
  1. Sysplex-wide security associations extend the latest z/OS Communications Server sysplex workload balancing and availability solutions to TCP/IP workloads associated with IPSec-protected traffic. This provides Workload distribution for IPSec-protected workloads, and enables IPSec protection for sysplex-based applications using Sysplex Distributor and/or dynamic VIPA Takeover/Takeback
  2. Sysplex-wide source VIPA support allows for a single IP-address appearance for distributed applications for both inbound and outbound connections

  • · FTP Server and Client Updates: The FTP Server and Client are enhanced as follows:
  1. Improved logging of messages associated with various types of activities, such as MVSä dataset allocation and deallocation, and connection activation and termination.
  2. A more consistent set of information, such as client IP address and port number, provided to all FTP security exits.
  3. The provision of a "scratchpad" work area to allow for the passing of information between exit routines.
  4. Compatibility of passive-mode ("firewall-friendly") FTP with the Sysplex Distributor function. Passive-mode FTP compatibility enables the availability advantages of Sysplex Distributor for customers with Web-browser-based FTP.

Additionally, the following enhancements benefit both the FTP Server and the FTP Client:

  1. Support of GB18030 (a new multibyte character set standard required by China) by using the IBM-5488 codepage.
  2. The ability to define a substitution character to be used when a non-mappable character is encountered during single-byte translation

  • Enhancements to the TN3270E Server: The TN3270E Server has several enhancements, including support for the latest TN3270E standards and improved security features:
  1. The TN3270 Server Secure Sockets Layer (SSL) support is enhanced to support Transport Layer Security (TLS). SSL is a protocol developed by Netscape to perform highly secure and encrypted data transmission. Transport Layer Security (TLS) is an upwardly-compatible successor to SSL developed by the IETF. The selection of SSL or TLS is negotiated during the SSL handshake and is transparent to the TN3270 Server.
  2. You will be able to define sets of TN3270 parameters and mapping statements at a more granular level than port, by associating each set with a specific destination IP address or linkname. This simplifies merging of existing TCP/IP stacks (due to corporate mergers or consolidations) because it allows the existing definitions and parameter sets to be preserved without requiring the assignment of additional TN3270 ports and corequisite client changes.
  3. The existing support for CICSâ autoinstall for terminals will be extended to provide a similar support for printer types, thereby reducing the labor associated with printer client changes.
  4. z/OS CS V1.2 added definitional flexibility by allowing a number of parameters from TelnetParms to also be specifiable on TelnetGlobals and ParmsGroup. z/OS V1.4 broadens this flexibility to include most of the remaining TelnetParms.
  5. Further definitional flexibility is provided by the provision of an option to allow a ParmsGroup to be mapped to an LUGroup on LUMAP and PRTMAP statements. This provides a mechanism for setting specific connection parameters based on the LU assigned to the connection
  6. A number of improvements are also available to the LU mapping function, including more flexible wildcard capability, the ability to supply an LU name through a user-written exit routine, the ability to retain an LU name-to-client identifier association for a specified amount of time after disconnect, and the optional issuing of a warning message once assignment from an LUGROUP or PRTGROUP has reached a user-defined threshold of that group's capacity

  • OSA SNMP Subagent Support: With z/OS V1.4, a new OSA SNMP Subagent and OSA-Express MIB, provided by the OSA (Open System Adapter) product, can be used with the Communications Server SNMP support to provide SNMP management data for OSA-Express features configured in QDIO mode. This support removes the prerequisite, Open Systems Adapter/Support Facility (OSA/SF), which is no longer required to manage SNMP data for OSA-Express features configured in QDIO mode running on a zSeries processor

  • Purge ARP Cache: This function provides a new command to purge all ARP cache entries for device types that maintain ARP caches. By having the ability to purge all ARP cache entries, entries that contain invalid ARP information can be purged and recreated dynamically at the next usage without waiting for ARP entry timeouts. This function can also be used to purge IPv6 neighbor cache entries

  • OSA-Express QDIO Broadcast Support: This function provides support for sending and receiving broadcast data through OSA-Express features when configured in QDIO mode. This allows customers to configure their OSA-Express features in QDIO mode when using applications that require broadcast support, such as DHCP and routing applications using Routing Information Protocol (RIP) Version 1