IBM SNA Networking

Document ID: 12242

Contents

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
VTAM Start Options
Allowing an APPN Resource to Connect to VTAM
Some Helpful Hints
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Related Information

Introduction

Virtual telecommunications access method (VTAM) is very complex, and migration to Advanced Peer-to-Peer Networking/Dependent LU Requester (APPN/DLUR) can cause headaches. Follow the tips in this document to ensure that an APPN/DLUR connection to VTAM goes smoothly.

Prerequisites

Requirements

To participate in an APPN network, the VTAM APPN end nodes (ENs) must have an extended session services capable network node (NN) server, to do any type of session initiation besides LU 6.2. Currently, this function is only provided in VTAM. Therefore, all VTAM ENs need to have VTAM network nodes as their NN servers.

Note: The Dependent LU Server (DLUS) feature in VTAM is only offered on NNs. A VTAM EN can not run DLUS.

Components Used

VTAM shipped APPN support in VTAM 4.1, but VTAM 4.2 contains DLUS, which allows dependent 3270-type sessions over an APPN network. There are many Program Temporary Fixes (PTFs) required for APPN/DLUR to run smoothly, as this is new technology in VTAM. An informational Authorized Program Analysis Report (APAR) exists for the DLUR feature and describes the PTFs required to run DLUS. Fewer problems have been reported with APPN and DLUR, when run with the most recent VTAM PUT levels.

Conventions

For more information on document conventions, refer to the Cisco Technical Tips Conventions.

VTAM Start Options

The following VTAM start options are related to APPN and are critical to run APPN successfully.

• NODETYPE—Set to NN if this VTAM is to be a network node or interchange node. Set to EN if this VTAM is going to be an end node or a migration data host.

  NODETYPE=NN
  

• CONNTYPE—This indicates the default connection type. If omitted, it defaults to LEN, which indicates that a specific override at the Physical Unit (PU) level is required to get APPN support. You must code CONNTYPE = APPN at either the start option level or at the PU level, to enable APPN connections to partner nodes.

  CONNTYPE=APPN
  

• CPCP—This needs to be set to YES, if CP-CP sessions are permitted with the partner nodes. If you set it to NO, it must be overridden at the PU level to allow CP-CP sessions with the partner.

  CPCP=YES
  

• DYNLU—This indicates that VTAM is able to create dynamic cross-domain resources (CDRSCs) for devices that are connected via APPN. If this is off (NO), the dynamic capabilities of APPN are practically useless. However, you can leave this off as a start option and then override at the PU level.

  DYNLU=YES
  

• DYNADJCP—This indicates that the APPN adjacent node control blocks can be built dynamically, instead of predefined. It must be set to YES for APPN, unless you also code an Adjacent Control Point Major Node.

  DYADJCP=YES
  

• CDRDYN—Similar to DYNLU, this controls the ability to create dynamic CDRSCs. It is critical to have this on (YES). In some versions of VTAM, this is coded in a cross-domain resource manager (CDRM) deck under the HOST CDRM, which is the CDRM that matches the host’s system services control point (SSCP) name.

  CDRDYN=YES
  

These options are used to tune and customize APPN, and they should be understood and considered by a VTAM APPN user. They are not, however, as critical for getting connections to work as the previous ones.

Allowing an APPN Resource to Connect to VTAM

VTAM requires a PU for each and every APPN device that connects to it. The PU may be created dynamically; but, if this method is chosen, the PU models must be set up so that APPN capabilities are on. CONNTYPE, CPCP, and DYNLU are critical if they are not already on by default at the start option level.

Some Helpful Hints

• The PU name must be unique to VTAM and must not equal the CPNAME. This is because a dynamic CDRSC will be created with the CPNAME, and VTAM can not handle PU names with the same names as CDRSCs.

• When you use APPN/DLUR, you configure the VTAM DLUS host CP name in the APPN definitions on the router.

  appn control-point NETA.CISCO dlus NETA.VTAM complete

  The DLUS name must match the VTAM SSCP name. Resources downstream from the DLUR should connect to an APPN-owned MAC address on the router, not to the FEP, 3172, or CIP-configured MAC address.

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