SNA Fundamentals

This three-day course introduces and explains the concepts, terminology, and operation of an SNA network. Emphasis is placed upon, but is not limited to, VTAM and NCP implementations of SNA. Additionally, traditional 'subarea' SNA, APPN, and APPC are explained in detail. This course is an essential requirement for all personnel working in or with an SNA network.

This course is available for one-company, on-site presentations.

What you will learn

On successful completion of this course you will be able to:

  • develop an extensive SNA vocabulary
  • identify the major SNA components and their role within the architecture
  • identify and use the various address structures used in SNA
  • describe the purpose and data flow characteristics of each session type
  • explain how chaining, bracketing, and pacing operate
  • identify the major SNA commands and command flows
  • characterise SNA requests and responses
  • interpret SNA message structures at each level
  • describe the operation of path control and it's components
  • list the characteristics of APPC communication
  • interpret SNA data link message structures in SDLC, Token Ring, X.25, and Frame Relay networks
  • describe the importance and use of APPC verbs
  • identify the APPN node types and explain their function
  • explain the principles of APPN routing and addressing.

Who Should Attend

This course is ideal for all personnel working in operations, systems programming, and networking departments. Programmers, analysts, network designers, and managers will also benefit.


No previous SNA knowledge or experience is required, although some familiarity with basic networking principles would be an advantage.


3 days

Fee (per attendee)

£1475 (ex VAT)

Course Code




What is SNA?; hardware and software; nodes and datalinks; SNA layers; bibliography.

Network Accessible Units

SNA NAUs; SSCP functions; CMC and data hosts; PU types and function; LU functions; NAU data flow; address awareness; network addresses message format.

SNA Sessions

Sessions and half-sessions; half session layers; session types; setup flows; initiation sequences; logon request processing; LU-LU session types.

SNA Message Structures

Message format and flow; RU categories; BIU structures; request header format; response header format; transmission header formats; additional TH fields; FID conversion.

Path Control

Path control functions; boundary node path control; intermediate node path control; transmission groups; explicit routes; virtual routes; VR activation; route selection; virtual route pacing; FID4 TH header format; segmentation and PIU blocking.

Session Data Flow

The NAU layers; session profiles; session level pacing; adaptive session level pacing; request chaining; bracketing; Send/Receive modes; function management headers; BIND command.

SNA Network Interconnection

Addressing limitations; SNI; gateway NCP functions; address translation; gateway SSCP functions; alias name translation; cross network logon sequence.

Advanced Program to Program Communication

SAA: APPC and SAA; LU6.2 sessions; conversations and sessions; required information; mapped and basic conversations; APPC verbs; Generalised data stream; GDS variables.

Advanced Peer to Peer Networking

Subarea SNA limitations; APPN differences; distributed database; route calculation; APPN routing & message format; high performance routing: principles, path switching, format.

Data Link Control (optional segment, in-house only)

DLC functions; SDLC: structure, frame format, addressing, control field formats; SNA in SDLC frames; Token Ring structure; Logical Link Control; Token Ring frame format; Token Ring addressing; Token Ring control; SNA in Token Ring frames; X.25: structure, X.25 packet format, addressing, packet control (QLLC); SNA in X.25 packets; Frame Relay: structure, frame format, addressing, control (RFC1490); SNA in Frame Relay frames; ATM: structure, cell format, addressing, control (RFC1483), Adaption Layer: SNA in ATM cells.

© RSM Technology 2021