IBM OS/390 User Manual
9.1.3.2 Programming
Any coding done under VSE, such as VTAM exits, will almost certainly need
rewriting (and will certainly need re-linking) for the OS/390 environment. Also,
some VTAM exit routines may be implemented differently under VSE and OS/390.
User-written VTAM programs and exits must be reviewed carefully for
compatibility. Please refer to the chapter
rewriting (and will certainly need re-linking) for the OS/390 environment. Also,
some VTAM exit routines may be implemented differently under VSE and OS/390.
User-written VTAM programs and exits must be reviewed carefully for
compatibility. Please refer to the chapter
Operating System Facilities in the
VTAM Programming manual.
9.1.4 Network Configuration
It is not unusual for a migrating customer to require multiple host access to the
SNA network. Multiple host configurations can serve to reduce or even eliminate
service disruptions during the migration process. Multiple host configurations
can provide for both interactive and batch traffic between all connected images.
This means that any terminal, regardless of to which host it is physically
connected, can access any VTAM application in the network, regardless of in
which host the application resides. In addition, SNANJE connections can be set
up between JES and PNET. For a migrating customer, these capabilities can be
particularly useful, providing simultaneous access to both old and new systems
as well as file transfer capability between them.
SNA network. Multiple host configurations can serve to reduce or even eliminate
service disruptions during the migration process. Multiple host configurations
can provide for both interactive and batch traffic between all connected images.
This means that any terminal, regardless of to which host it is physically
connected, can access any VTAM application in the network, regardless of in
which host the application resides. In addition, SNANJE connections can be set
up between JES and PNET. For a migrating customer, these capabilities can be
particularly useful, providing simultaneous access to both old and new systems
as well as file transfer capability between them.
VTAM provides for two different multiple host networking architectures,
traditional SNA subarea (cross domain) and/or APPN (Advanced Peer-to-Peer
Networking). VSE/VTAM V3R4 is limited to SNA subarea because it does not
provide full APPN capability. The MultiDomain package of VSE/VTAM V4R2 is
required to support multiple host connectivity in an SNA subarea network. VSE
VTAM V4R2 provides APPN capability at all three functional levels, but with
some limitations in the Client/Server and MultiDomain packages. OS/390 VTAM
is full featured and provides both SNA subarea and APPN capabilities.
Implementation requires careful planning and solid networking skills. Some
points to consider in network design are:
traditional SNA subarea (cross domain) and/or APPN (Advanced Peer-to-Peer
Networking). VSE/VTAM V3R4 is limited to SNA subarea because it does not
provide full APPN capability. The MultiDomain package of VSE/VTAM V4R2 is
required to support multiple host connectivity in an SNA subarea network. VSE
VTAM V4R2 provides APPN capability at all three functional levels, but with
some limitations in the Client/Server and MultiDomain packages. OS/390 VTAM
is full featured and provides both SNA subarea and APPN capabilities.
Implementation requires careful planning and solid networking skills. Some
points to consider in network design are:
•
Number of hosts
•
Number of applications
•
Number of terminal resources
•
Number of NCPs
•
Traffic patterns
•
Future growth
•
Backup/redundancy requirements
•
Bandwidth requirements
•
Operation/management
•
Security
•
Cost
Concepts and technical explanations, as well as implementation techniques for
SNA networking in both subarea and APPN designs, can be found in the
following manuals:
SNA networking in both subarea and APPN designs, can be found in the
following manuals:
•
IBM Network Products Implementation Guide, GG24-3649
•
VTAM Network Implementation Guide, GC31-8370
Chapter 9. Telecommunications S u b s y s t e m s
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