Digi TransPort WR11 User Manual page 650

Configuring legacy protocols
the user data field of the call packet.
CALL R, G12, NM YNUI - 56512120DHel l o
Note The particular facilities available vary among X.25 service providers.
If a CALL command is issued without the address parameter, it is assumed you want to go back on-
line to a previously established call, using the PAD recall facility to temporarily return to the PAD>
prompt.
Fast select (ISDN B-channel only)
When the standard Fast select facility is requested using the F facility code, the call packet generated
by the CALL command is extended to allow the inclusion of up to 124 bytes of user data. For example:
CALL F- 1234567890DThi s DATA s ent wi t h c al l pac ket
causes an X.25 CALL packet to be sent using the Fast select facility including the message This DATA
sent with call packet. The Carriage Return for entering the command is not transmitted. If the Fast
select facility code is not included, only the first 12 characters are sent.
When a Fast select CALL has been made, the PAD accepts an extended format response from the
called address. This response, consisting of up to 124 bytes of user data, can be appended to the
returning call accepted or call clear packet. When one of these packets is received, the user data is
extracted and passed from the PAD to the terminal immediately prior to the CLR DTE . . . message in
the case of a call clear packet or CON COM message in case of a call accepted packet.
When a restricted response Fast select call has been made using the Q facility code, the call packet
indicates that a full connection is not required, so that any response to the user data in the CALL
packet should be returned in a call clear packet.
When the PAD receives an incoming call specifying Fast select, the call is indicated to the terminal in
the normal way. For example:
I C 1234567890 FAC: Q, W : 2 COM
indicates that an incoming call had been received requesting Restricted response fast select and a
window size of 2. The user (or system) then has 15 seconds in which to pass up to 124 bytes of data to
the PAD to be included in the clear indication packet that is sent in response to the call.
The PAD does not differentiate between standard and restricted response Fast select on incoming
calls and, consequently, will always respond with a clear indication.
Network User Identity (NUI)
The N facility code allows you to include your Network User Identity in the call packet. For security
reasons, the PAD echoes each character as an asterisk (*) during the entry of an NUI. Some X.25
services use the NUI field to pass both a username and password for validation. For example, if your
username is MACDONALD and your password is ASDF, a typical CALL command would have the
format:
CALL NM ACDONA; ASDF- 56512120
where the ; character separates the username from the password.
Closed User Group (CUG)
Most X.25 networks support Closed User Groups. Closed User Groups restrict subscribers to only
making calls or receiving calls from other members of the same CUG. The CUG number effectively
provides a form of sub-addressing working with the NUA to identify the destination address for a call.
Digi TransPort® Routers User Guide
Configure X.25 parameters
650