Introduction to SNA Server/6000

AIXLink/X.25 1.1 for AIX: Guide and Reference

Introduction to SNA Server/6000

SNA Server/6000 implements two SNA components that control the operation of the local node in the network. These components are as follows:

Physical Unit (PU) SNA Server provides the capabilities of a PU Type 2.1 node.
Logical Unit (LU) classified as one of the following types:
LU0 Program-to-program.
This logical unit manages communication between devices associated with the retail industry (for example, point of sale terminals). It provides primary and secondary LU support through an application programming interface (API) .
LU1 Host program to RJE workstation .
This protocol manages many input/output devices such as printers, card readers and punches, storage devices, and an operator console.
LU2 Host program to display.
Used by applications related to the emulation of a IBM terminal, allowing keyboard input, display output, and file transfer, using the SNA display data stream.
LU3 Host program to printer.
Used by applications related to the emulation of an IBM -attached printer allowing for printed output, using the SNA printer data stream.
LU6.2 Advanced Program-to-Program Communications (APPC) .
For communications between two programs on a peer-to-peer basis.

SNA Configuration Profiles

SNA Server/6000 keeps all network information in structured files called profiles. It stores the profiles as database files that are controlled by system data management routines.

The profiles needed to use the 3270 host connection program with X.25 are:

SNA	Describes the default characteristics of the SNA program and its environment, that is the maximum number of sessions (recommended value 200+), maximum number of conversions, restart action, standard input and output devices, and so forth.
Links	Profiles used to support physical connectivity between SNA nodes. The DLC types represented include token ring, Ethernet, X.25, FDDI, and SDLC. Also affords the ability to control LU0 Primary Line and APPN Connection Network profiles.
X.25 SNA DLC	Defines datalink device name (for example, x25s0, same as the COMIO interface name), maximum I-field size, local X.25 network address (NUA), transmit and receive window counts, maximum number of active link_stations, and various polling frequencies, counts, and secondary inactivity time-out values.
X.25 Link Station	Defines local XID node ID, SNA DLC profile name, response to link inactivity, LU address registration, link trace and depth, CCITT level, station type, link activation parameters, virtual circuit type, supported session types, restart parameters, transmission group characteristics, and logical channel number (LCN).
X.25 Optional Facilities	Defines optional facilities including throughput classes, closed user group characteristics, network user identification, reverse charging, RPOA, and so forth.
Sessions	Profiles used to support session connectivity between supported LU types: Generic LU, LU0, LU1, LU2, LU3, and LU6.2

Session profiles define and register LU addresses, primary and secondary LU0 logical units and corresponding link station profile names, system services control point (SSCP ID), network name and remote LU name for LU1, LU2, and LU3 profiles, and for LU6.2 profiles: local and partner LU profiles, side information profiles for CPIC applications, mode profiles, transaction program name profiles, session and conversation security profiles, session time-out profiles, class of service profiles, and partner LU 6.2 location profiles.

Control Point	The control point profile defines the local node's function in the network as well as uniquely identifying itself on the network (through the CP name). The control point is the default INDEPENDENT LU 6.2 LU for the system. The XID node ID value identifies this node when a link station profile specifies to use the control point's XID instead of supplying one of its own.
Security Profiles	Used to add, remove, or change a communications authority password (CAP) to secure the configuration database.

For additional information on SNA configuration and profiles, see AIX SNA Server/6000: User's Guide, Order Number SC31-7002, and AIX SNA Server/6000: Configuration Reference, Order Number SC31-7014.

SNA Configuration Commands

A set of configuration commands is provided with SNA Server/6000 to assist with and accomplish network configuration and setup. An extensive list of these commands can be found in : Command Reference, Order Number SC31-7100, and : Configuration Reference, Order Number SC31-7014. A few of the more commonly used commands are:

mksnaobj

Creates profiles.

mksnaobj -t ProfileType [-w link_type|-u lu_type] \
 
[-T template_profname] [suboptions... ] ProfileName

chsnaobj

Changes the values in previously defined profiles.

chsnaobj -t ProfileType [-w link_type|-u lu_type] \
 
[suboptions... ] ProfileName

rmsnaobj

Removes a profile.

rmsnaobj -A | -t ProfileType [-w link_type|-u lu_type] \ 
 
ProfileName [ProfileName ...]

qrysnaobj

Retrieves information of a defined profile.

qrysnaobj [-C] [-S | -L] -t ProfileType [-w link_type| \
 
-u lu_type] ProfileName

sna

Starts or stops SNA, sessions, link stations, traces, logging options, and so forth.

sna {-start(-s) [sna | session(s) | link_station(1) | \ 
 
anynet] -stop | -display | -trace(-t) | -setlogs} \
 
[Options]
 
sna -start(-s) session(s) [ [Flag Value] ...]
 
sna -start(-s) session(s) [ [Flag Value] ...](LU6.2 only)
 
[-local_lu_name(-ln) Name | -local_lu_alias(-la) Alias]
 
{-partner_lu_name(-pn) Name | -partner_lu_alias(-pa) \ 
 
Alias} -mode(-m) Name [-session_type(-st) conwinner(cw) \ 
 
| conloser(cl)]
 
sna -start(-s) link_station(l) -profile(-p) Value

verifysna

Verifies profiles in the working directory and optionally updates committed verified directory entries.

verifysna {[-R] | [-U] } [-B backup_ascii_file]
 
                         [-S backup_security_file]

-R	Verifies dynamic reconfiguration.
-U	Update committed database if verification is successful.
-B backup_ascii_file	Create a flat ASCII backup file.
-S backup_security_file	Create backup binary security file.

SNA Server/6000 Profile Types and Profile Parameters

The following table lists some of the common profile types, their corresponding profile parameters, and a brief description.

AIX SNA Server/6000 Profile Types and Profile Parameters
Profile Type	Profile Parameter	Description
SNA System Defaults	-t'sna'	SNA Node Defaults
X.25 SNA DLC	-t'sna_dlc_x.25'	Data Link Control
X.25 Link Station	-t'link_station_x.25	Link Station
X.25 Optional Facilities	-t'x.25_opt_facs'	X.25 Facilities
Control Point	-t'control_pt'	Local Node Identification
Session (LU0, LU1, LU2, LU3, and LU6.2	-t'session'	Application Sessions
LU 6.2 Local LU	-t'local_lu'	LU6.2 Characteristics
LU 6.2 Side Information Requirement	-t'side_info'	Dependent LU6.2
LU 6.2 Partner LU	-t'partner_lu6.2'	Session Characteristics
LU 6.2 Mode Definitions	-t'mode'	Control and Pacing
LU 6.2 TPN Name	-t'local_tp'	Transaction Program
LU 6.2 Session Security	-t'session_security'	Password Specification
Partner LU 6.2 Location	-t'partner_lu6.2_location'	Remote LU Location

SNA Server/6000 Components

SNA Server/6000 is comprised of:

AIX device drivers.
A set of background processes that run under the control of the System Resource Controller (SRC) .

The System Resource Controller, in turn, provides all services to transfer data over the network. To provide these services, the SRC requests information from the profile and data management components to define the characteristics of connections and link stations on the network. Refer to AIX Version 4.3 General Programming Concepts for more information on the SRC.

SNA Device Drivers

The following AIX device drivers are part of SNA Server/6000:

SNA Data Device Driver	Provides the AIX subroutine interface to SNA Server/6000.
SNA Manager Device Driver	Provides an interface for the SNA Server/6000 background processes to AIX subroutines that implement control functions internal to SNA Server/6000. The SNA Manager Device Driver interface is for the exclusive use of the SNA Server/6000 background processes.
SNA Generic Device Driver	Provides a PU level subroutine interface for generic LU application. The LU0 support provided with SNA Server/6000 is written to the generic device driver interface.

These device drivers must be present for SNA Server/6000 to function properly. They should appear in a listing of the /dev directory as /dev/sna, /dev/snam, and /dev/gsna, respectively.

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