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DIGITAL SNA access server migration guide

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How the DECnet SNA Gateway Establishes LU Names

The DECnet SNA Gateway establishes a unique LU name for a session using PU name and session address. There are a variety of different access routines that may be in use on your existing DECnet SNA Gateway. Table 3-4 shows some of the various ways that an OpenVMS access routine may generate old-style LU names to identify an LU.

Table 3-4: DECnet SNA Gateway Access Parameters

OpenVMS Access Routine Command	Example Old-Style LU Name
$set host/sna/access_name=snate atog	SNA-0.1, ... , SNA-0.14 where SNA-0 is PU defined in Access Name
$set host/sna/access_name=snate/sess=14 atog	xxxxx.14 where xxxxx is PU defined in Access Name
$set host/sna/access_name=snate/pu=sna-0 atog	SNA-0
$set host/sna/access_name=snate/pu=sna-0 /sess=14 atog	SNA-0.14

To facilitate network access on a DECnet SNA Gateway, you may create Access Names that enable the gateway to identify an LU name based on the Access Name parameters. An Access Name is defined in the SET ACCESS NAME command of the DECnet SNA Gateway configuration file, as shown in Figure 3-5.

Figure 3-5: Example DECnet SNA Gateway Access Name Definition

SET ACCESS NAME SNATE -
LU LIST 1-14 -
APPLICATION TSO -
LOGON MODE TE -
PU SNA-0

When an OpenVMS SNA application wants to communicate with the IBM host, it may specify an Access Name to be used to establish a session. The DECnet SNA Gateway determines the old-style LU name by using the physical unit (PU) name and a session address drawn from the LU LIST defined for that Access Name:

• The PU name is typically 3 alphanumeric characters (for example, SNA), a hyphen, and a PU address (0-3); for example, SNA-2 or SNA-0.
• The session address is in the range 1-255; the range is bounded by the SET PU LU LIST parameter of the configuration file. The range of addresses that can actually be used to establish a session for a particular Access Name is defined in the LU LIST parameter for the specific Access Name, as shown in Figure 3-5, above.

The old-style LU name is constructed from the PU name and the next not-in-use session address defined for the Access Name, as follows:

pu_name.session_address

This yields an old-style LU name of

SNA-0.12

for the above example with an available session address of 12 on PU SNA-0.