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Note: Although using this technique ensures our LU names will be unique
within the subnet, it is possible that two machines from different subnets will
connect to the same CICS region, causing a potential name clash. In this
case, we suggest that you ensure that you only use three (or less) substitution
characters and that the fifth characters in the LU name template is different for
each subnet.
To help you in determining what a given TCP62 LU name will be for different
inputs, we developed a sample utility, tcp62locallu.exe, that takes a given IP
address, subnet mask, and LU name template, and generates the LU name that
TCP62 will use. This use of this utility is illustrated in Figure 3-3 and it is provided
with the additional material for this book.
Example 3-3 tcp62locallu utility
C:> tcp62locallu.exe CCLIE*** FFFFFE00 9.1.38.39
Local LU template: CCLIE***
Address mask : FFFFFE00
IP address : 9.1.38.39
Local LU is CCLIEE17
Configuring TCP/IP host names
Since TCP62 flows SNA LU 6.2 packets over TCP/IP, you need to define a
mapping of the SNA partner LU name to an IP address. Our partner LU is our
CICS region, with a fully qualified LU name of USIBMSC.SCSCPJA1. This needs
to be mapped to the IP address of our z/OS system wtsc66, which is 9.12.6.6.
The function in TCP62 achieves this by generating a host name from the
concatenation of the following elements separated by periods:
LU name (5) + network name of the LU (4) + domain name suffix (2)
We defined a mapping of this host name to the IP address of our z/OS system
using the TCP/IP hosts file (C:\WINNT\system32\drivers\etc\hosts) on our
Windows 2000 workstation. The following is the line we added to our hosts file.
9.12.6.6 SCSCPJA1.USIBMSC.ITSO.IBM.COM
If you wish to use the same CTG.INI configuration file across multiple client
workstations, you will also need to provide a means of resolving the TCP62 host
name to the correct z/OS IP address on all workstations. Instead of just using the
TCP/IP hosts file, it is possible to add an entry to the Domain Name System
(DNS) server used by the workstations.
Chapter 3. TCP62 connections to CICS 51