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34 S/390 PID: ThinkPad Enabled for S/390
4.2.5 TCP/IP for OS/390
It is possible to share a single Ethernet LAN adapter in the ThinkPad between Linux
(including the FLEX-ES Terminal Solicitor) and OS/390 TCP/IP. This requires some
coordination between the FLEX-ES definitions and the OS/390 TCPIP profile data set
parameters. Our goal was to assign IP address 9.12.17.211 to OS/390 TCP/IP, using the
OS/390 device addresses E20 and E21 for the interface. (Our Linux IP address was
9.12.17.210.)
We included the following FLEX-ES definitions:
System definition:
channel (3) local
cu devad(0xE20,2) path(3) resource(R10A3172)
Resource definitions:
R10A3172: cu 3172
interface local(1)
options ‘ipaddress=9.12.17.211’
device(00) 3172 eth0
device(01) OFFLINE
end R10A3172
We changed the following lines in the TCPIP.PROFILE.TCPIP data set:
...
DEVICE LCS1 LCS E20
LINK ETH1 ETHERNET 0 LCS1
...
HOME 9.12.17.211 ETH1
...
GATEWAY
9 = ETH1 1492 0.255.255.0 0.12.17.0
...
START LCS1
This specifies the use of LAN adapter 0 (sometimes known as the MPTS adapter number,
from the OS/2 MPTS program). Adapter 0 is the default LAN adapter number for FLEX-ES.
This number is not related to any Linux LAN number.
In order to share an Ethernet adapter with Linux, we must specify, in the resources file, the IP
address to be used by OS/390. It must also be specified in the OS/390 TCP/IP profile data
set, as shown here. With the specifications described here, we have these connection
options from another host on the network:
TN3270 to 9.12.17.210, port 24 -- this connects to the Terminal Solicitor (assuming resadm
is started. We can then select a session and should receive the USSTAB logo screen.
TN3270 to 9.12.17.211, port 23 -- this connects directly to OS/390 TCP/IP. In recent AD
systems (where a USSTAB function is defined for TCP/IP) this should produce the logo
screen.
telnet to 9.12.17.210, port 23 -- this connects to Linux (if telnet connections are enabled).
telnet to 9.12.17.211, port 1023 -- this connects to OS/390 Unix System Services, as an
ASCII terminal (assuming you are using a recent AD system).
telnet to 9.12.17.211, port 23 -- this produces a line-mode connection (via VTAM) to TSO
and is not very useful.