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8 Configuring TN3270 Server on the Channel Interface Processor
VTAM Host Configuration Considerations for Dynamic LU Allocation
SNA Session Switch—End Node DLUR
An end node DLUR function is implemented as part of the TN3270 server. The purpose of the
DLUR is to allow the routing of TN3270 LUs to multiple VTAM hosts to be performed in the CIP
card rather than on the VTAM hosts. The need for this feature will increase with the introduction of
the new multi-CPU CMOS mainframe which comprises up to 16 CPUs that appear as separate
VTAMs.
The implementation of TN3270 server LUs under DLUR also allows the server to learn about the
LU names on the ACTLU, which greatly simplifies the configuration to support specifically
requested LUs such as printers.
Multiple Hosts Support
The TN3270 server supports access to multiple hosts via the configuration on a PU basis (Table 4).
PUs connected to different hosts or applications can be configured with different IP address.
From the pu (direct) TN3270 configuration command values shown in Table 4, PU X2 establishes
a link to a host at SAP 8 on MAC address 4100.cafe.0002. A client connecting to IP address
171.69.176.43 is allocated an LU from that PU and is routed to that host.
Note that by using the DLUR function, all the LUs in the server can be defined and owned by a
controlling VTAM. When a client requests an application residing on a different VTAM host, the
controlling VTAM will issue the request to the target host which will send a BIND directly to the
client. All LU-LU data willthen flow directly betweenthe target host and theclient without needing
to go through the controlling VTAM.
VTAM Host Configuration Considerations for Dynamic LU Allocation
Other non-Cisco implementations of TN3270 support depend on predefined, static pools of LUs to
support different terminal types requested by the TN3270 clients. The CIP TN3270 server
implementation removes the static nature of these configurations by using a VTAM release 3.4
feature, dynamic definition of dependent LU (DDDLU). (Refer to the VTAM operating system
manuals for your host system, under the descriptions for LUGROUP for additional information.)
DDDLU dynamically requests LUs using the terminal type provided by TN3270 clients. The
dynamic request eliminatesthe need to defineany LU configurationin the server to supportTN3270
clients emulating a generic TN3270 terminal.
To supportDDDLU, thePUs used bythe TN3270server have tobe definedin VTAMwith LUSEED
and LUGROUP parameters as shown in Figure 2.
Table 4 Direct PU Configuration in Router
Comman
d
PU
Name IDBLK IP-address Type
Adapte
r
number LSAP RMAC RMAC LU-seed LU-name
pu X1 05D30001 192.195.80.40 tok 1 4 rmac 4100.cafe.0001 lu-seed TN3X1###
pu X2 05D30002 171.69.176.43 tok 1 8 rmac 4100.cafe.0002 lu-seed TN3X2###