IBM 3708 Description page 79

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Example of Eslablishinga Session
The command flow sequence required to establish a session is summarized in
Figure 3-1 on page 3-11. The command flow nomenclature is generalized and
access method specific macro names are not used. The example illustrates the
connection process to one 3708 SLU and includes the following assumptions:
• No sessions are originally activated between the host and the 3708.
• The device connected to the 3708 is a keyboard display.
• No 3708 logon screens have been suppressed.
• The 3708 port has been defined for autobaud/autoparity and has a port
password defined.
The access method sends the ACTPU command to establish the SSCP-PU session
#1.
(See
#1
in Figure 3-1 on page 3-11.) An ACTLU command 12 is then sent to
establish the SSCP-PLU and SSCP-SLU sessions. Typically, the SSCP would send
an ACTLU command for each of the LUs defined for the 3708 in the host
generation.
After transmitting a positive response to the ACTLU command, the 3708 sends a
NOTIFY command #3 to the SSCP. This command tells the SSCP that although
the LU in the 3708 has been activated, the device attached to that LU is not
available for use (powered oft). The 3708 SLU considers all devices powered ofT
until a host selection is made.
After the display terminal operator has logged on to the 3708 #4, the 3708 transmits
another NOTIFY command #5 to inform the SSCP that the display is active and
ready to communicate with a host application. The 3708 transmits the NOTIFY
immediately after the terminal operator has made a host selection.
If all 3708 logon screens are excluded, the NOTIFY (power on) is transmitted when
the 3708 detects that the downstream device is powered on. If the Host Selection
screen (C3) is suppressed, the NOTIFY (power on) is transmitted after the terminal
type is determined.
If an SSCP Good Morning message, such as the VTAM USS message 10, is defined in
the host, the SSCP message is transmitted through the 3708 to the display #6. This
message, if defined, displaces the 3708 Logon Indication (C4) screen.
NQte: IfVTAM transmits the message 10 before the 3708 sends NOTIFY (power
on), the 3708 rejects the message with a negative response (X'083l').
The network is now ready for LU-LU sessions to be established.
3-10
IBM 3708 Description