IBM SC30-3865-04 - Manual (Page 50)

The interval between attempts is doubled each time an attempt fails until a
maximum interval of one day is reached. From that point on, the attempt is
performed daily.
Note: If an explicit focal point initiates a management session with a device, it will
cause a session with an implicit focal point to terminate.
Dynamic Definition of Dependent LUs (DDDLU)
The dynamic definition of dependent LUs (DDDLU) is a VTAM facility that allows
the logical units to be known by VTAM when they connect to VTAM, rather than
during the major node activation of the related PU. With this support, VTAM builds
LU definitions from reusable model LU definitions instead of using predefined LUs.
The LU definitions are replaced or changed each time the device containing the
LU(s) powers on (or notifies that it is enabled and startable).
The DDDLU capability requires some minor changes in VTAM and depends on the
activation of the physical unit (PU) being done by a format-1 ACTPU. This format-1
ACTPU can carry the PU Capabilities Control Vector, and should be sent only to
devices that send an XID3 with byte 10, bit 3 set to ’1’ (this PU supports format-1
ACTPU). The PU Capabilities Control Vector will tell whether the sending node
supports unsolicited NMVTs (network management vector transport) for Reply
Product Set ID (PSID). If unsolicited NMVTs for Reply PSID are supported, DDDLU
can be achieved.
The Reply PSID NMVT contains the local address of each LU, a power on/off
indicator, the machine type and model number of the device, and optionally other
device-dependent information needed to define the logical units. VTAM uses this
information to choose an appropriate model LU definition statement to build an LU
definition.
TN3270E Server
The TN3270E Server provides a TN3270 gateway function for TN3270 clients that
are downstream of a SNA host running a 3270 application. These clients connect to
the server using a TCP connection. This connection is mapped to a SNA dependent
LU-LU session that the server maintains with the SNA host. The TN3270E Server
handles the conversion between the TN3270 datastream and a SNA 3270
datastream. The TN3270E Server function complies with RFC 1646 and RFC 1647.
TN3270 sessions can span APPN networks as well as IP networks using the HPR
over IP.
The TN3270E Server can use a subarea connection or the APPN DLUR function to
communicate with the host.
See “Support for Subarea SNA Connections from the TN3270E Server to the Host”
on page 23 for more information and see “Configuring TN3270E Using DLUR” on
page 75 and “Configuring TN3270E Using a Subarea Connection” on page 77for
sample configurations.
If you are using DLUR to communicate with the host, the local PUs used by the
TN3270E Server need to be configured in the host as DLUR internal PUs. The
following code is an example of the host VTAM configuration:
APPN
20 MRS V3.2 Protocol Config Ref Vol 2
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