SNAX Connection Manager (SNAX/CM) Manual
Components of a SNAX/CM Environment
Introduction to SNAX Connection Manager (SNAX/CM)
097842 Tandem Computers Incorporated 1–3
Alias LU Names An alias LU name is a temporary LU name assigned only for the duration of a
connection, whether that connection is made to an X.25 or a Token-Ring network. An
alias LU name is constructed by the service manager and sent to a requesting APPL
object of the type CMAPPL (which denotes that SNAX/CM is managing the
connection) when a port and a PU connect. Note that alias LU names are valid for
X.25 or Token-Ring networks on switched lines.
Because an LU opened using an alias is valid only for the duration of one connection,
alias LU names can be used to limit access to an LU to one specific connection.
Updating alias LU names also prevents applications from using a subsequent
connection without recognizing that a disconnect has occurred.
SNAX/XF generates alias LU names starting with the first configured LU, and returns
the alias names to SNAX/CM when a connection is made. SNAX/CM then passes the
aliases in a CONNECTED message to the user server process, which can use them to
access connected LUs.
When a line or port is disconnected (whether intentionally or not), the LU alias
generated for that connection no longer exists. Any application opener using the old
alias LU name receives file-system error 14, notifying the application that a device
does not exist (except for CLOSE requests which are processed as usual).
Note If the SNALU protocol is used with SNAX/XF, the CLOSE request must be issued before an application
can send an OPEN request to the LU for a subsequent connection.
SNAX/XF uses the number of LUs connected to construct all the LU aliases for a
connected PU. Aliases are generated in the following format:
$
line
.#
axnnnnn
The line name is followed by the symbol #, with one alphabetic character, one
alphanumeric character, and a 5-digit number all assigned by SNAX/XF to make the
name unique.
The first LU configured is assigned the base alias LU name at the time of connection.
The alias LU name for the first LU on the PU always ends in the digit 1. The five-digit
number of the base) LU alias is incremented by 1 for each additional alias. (
lucount
in the CONNECTED message sent to the user server signals the number of LUs
connected.)
Table 1-1 lists some example alias LU names generated for three LUs configured on
one PU.