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  1. Introduction
  2. Network Topology
  3. Hardware Connections
  4. TCP/IP Ports and Addresses
  5. Network Protocol Levels
  6. Data Link Layer and IEEE
  7. Network Protocol Categories
  8. Repeaters, Bridges, Routers
  9. ARP and RARP Address Translation
  10. Basic Addressing
  11. IP (Network)
  12. TCP (Transport)
  13. UDP (Transport)
  14. ICMP
  15. Hardware Cabling
  16. Wireless media
  17. Outside Connections
  18. Ethernet
  19. Token Ring
  20. ARCnet
  21. AppleTalk
  22. FDDI
  23. IPX/SPX
  24. NetBEUI
  25. AppleTalk
  26. SNA
  27. Others
  28. Simple Routing
  29. More Complex Routing
  30. IP Masquerading
  31. Firewalls
  32. Domain Name Service (DNS)
  33. Virtual Private Networking
  34. DHCP
  35. BOOTP
  36. RPC and NFS
  37. Broadcasting and Multicasting
  38. IGMP
  39. Dynamic Routing Protocols
  40. Simple Mail Transfer Protocol (SMTP)
  41. Simple Network Management Protocol
  42. Network Services
  43. Installing Drivers
  44. Network Operating Systems
  45. Applications
  46. Wide Area Networks
  47. Backing up the network
  48. Fault Tolerance
  49. Troubleshooting
  50. Commonly used Network Ports
  51. Networking Terms and Definitions
  52. Networking RFCs and Protocols
  53. Further Reading
  54. Credits

System Network Architecture

System Network Architecture (SNA) by IBM is a suite of protocols mainly used with IBM mainframe and AS/400 computers. Two SNA protocols are:

  • APPC - Advanced Peer-to-Peer Communications provides peer to peer services at the transport and session layer.
  • APPN - Advanced Peer-to-Peer Networking supports the computer connections at the network and transport layers.

Microsoft produced the SNA Server so PC networks could connect with SNA networks.

SNA Layers

SNA has its own network model which is:

  • Physical
  • Data link - Uses protocols such as token-ring or Synchronous Data Link Control (SDLC).
  • Path Control - Performs routing, division, and re-assembly of data packets.
  • Transmission - Connection software
  • Data flow - Prevents data overflows by monitoring and handling traffic
  • Presentation - Handles interfaces to applications
  • Transaction - Provides an interface for applications to use network services

SNA Network Devices

  • host systems
  • terminals
  • Output devices
  • Communications controllers
  • Cluster controllers - Allow many devices to connect through them. They connect ot a host or communications controller.

SNA Network Categories

  • Nodes
    • Type 2 - PCs, terminals and printers
    • Type 4 - Communications controllers
    • type 5 - Host computers used to manage the network
  • Data links - Connection between combinations of hosts, cluster controllers, or nodes.

Possible SNA communications architectures

  • SDLS - Synchronous Data Link Control
  • BSC - Binary Synchronous Communication sends bits in frames which are timed sequences of data.
  • Token-ring
  • X.25
  • Ethernet
  • FDDI

SNA units

NAU - Network Addressable Units

  • LU - Logical Units are ports that users use to access network resources
    • Type 1 - An interactive batch session
    • Type 2 - An IBM 3270 terminal
    • Type 3 - An IBM 3270 printer
    • Type 6.2 - A program to program session
    • Type 7 - An IBM 5250 family session
  • PU - Physical Units are a network device used to communicate with hosts.
    • Type 2 - Cluster controllers
    • Type 3 - Front end process
    • Type 5 - Host communications software

SNA software components

  • SSCP - Systems Services Control Point manages all resources in the host's domain.
  • NCP - Network Control Program performs routing, session management tasks. It runs in the communications controller.