Table Of Contents
LU Pooling and ASSOCIATE Command Support
Product Bulletin, No. 904
New Features for Cisco TN3270 Server
Release 11.2(18)BC, 12.0(5)T, and future releases of Cisco IOS® software offer additional TN3270 Server features that provide ease in configuration, management, and usability for Cisco TN3270 users. These new features:•
Provide logical unit (LU) pooling capability to support ASSOCIATE command functions and ease configuration scenarios.
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These features extend Cisco's industry-leading TN3270 Server products, continuing Cisco's commitment to IBM mainframe access using standards-based IP solutions.
LU Pooling and ASSOCIATE Command Support
Many SNA applications contain capabilities that associate a printer with a specific terminal device to simplify printing. For instance, many Customer Information Control System (CICS) applications define a PF key that allows a simple way for an end user to print. The print job is sent to a printer associated with the end user. This task is accomplished by configuring a relationship between the screen LU and the printer LU. Internet Engineering Task Force (IETF) RFC 1647 defines a means to preserve these associations in a TN3270 environment using an ASSOCIATE command.Cisco TN3270 Server has been enhanced to support the ASSOCIATE request through LU pooling, providing an easy way to configure the relationships between screen and printer LUs. The LU pooling feature allows clients to be nailed or specified to LUs. This enhancement allows you to configure clusters of LUs within an LU pool. Because a cluster can contain screen LUs and their associated printer LUs, this function provides the capability to "associate" a screen LU with a printer LU. When a client requests an LU, it is dynamically assigned an LU from a cluster within the appropriate pool (as defined by LU nailing). If it requests a subsequent LU and requests one associated with its current LU, it is automatically assigned an LU from the cluster. This feature greatly simplifies the configuration required to enable the ASSOCIATE function.
Response Time Support
End users accessing mainframe applications—regardless of whether they access them from 3270 or TN3270 clients—require consistent response time. Applications such as Tivoli NetView Performance Monitor and Computer Associate's NetSpy provide mainframe access to end-to-end session response time data. However, in a TN3270 environment, many enterprises prefer to access this data from an Simple Network Management Protocol (SNMP) network management platform. In addition to speed problem isolation, enterprises need more granular information. In particular, they need the ability to break down end-to-end response time between the response time upstream and the response time downstream from the TN3270 server. The TN3270 Server Response Time MIB (TN3270E-RT-MIB) now provides both the mainframe-to-TN3270 Server response time and TN3270 Server-to-client response time. This additional information is vital to isolate and resolve response time problems.LU Deletion
With the latest release of VTAM (4.4.1), VTAM has enhanced how it manages control block space and LU usage. VTAM allocates LU control blocks based on defined LU model types. If a client accesses VTAM with multiple model types, each model requires a different LU control block from the LU pool. In previous releases, these control blocks were never deleted and the LU was never released back into the LU pool. TN3270 Server now supports an LU deletion command. This command specifies whether the TN2370 server sends a REPLY-PSID power-down request to VTAM when a client disconnects, providing a capability for VTAM to return the unused LUs to the pool. This command is recommended in host environments running VTAM version 4.4.1. Previous versions of VTAM are not compatible with network management vector transport (NMVT) REPLY-PSID.LU Termination
With some applications (such as CICS), customers have reported that users could acquire the session of a previous user, a situation called "tail-gating." This activity occurs when an application does not relinquish or terminate the LU properly. For environments exhibiting this security problem, a feature has been added to allow the TN3270 Server to support SNA TERMSELF RU. This feature will force the termination of the session and session requests associated with an LU when users turns off their devices or disconnect, avoiding the previous scenario.Orderability
These new features are included without additional charge in TN3270 Server software running on any Cisco Channel Mainframe Connection (CMCC)—the Channel Interface Processor (CIP) and Channel Port Adapter (CPA). This support is in Cisco IOS images 11.2(18)BC (used for the CIP), and in Cisco IOS images 12.0(5)T (for the CPA) and later.