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  1. Introduction
  2. Network Model
  3. Topology
  4. Physical Media
  5. Wireless Media
  6. Network Card
  7. Modems
  8. Outside Connections
  9. Wide Area Network Connections
  10. Repeaters, Bridges, Routers
  11. Network Types
  12. Ethernet
  13. Token Ring
  14. ARCnet
  15. AppleTalk
  16. FDDI
  17. Architecture Comparisons
  18. Categories
  19. TCP/IP
  20. IPX/SPX
  21. NetBEUI
  22. AppleTalk
  23. SNA
  24. Others
  25. Suites and Network Layers
  26. Installing Drivers
  27. DNS
  28. Network Operating Systems
  29. Applications, mail, groupware, DBMS
  30. Backing up the network
  31. Troubleshooting
  32. Web, SNMP, admin, firewalls
  33. Networking Terms and Definitions
  34. Credits

ARCnet (Attached Resource Computer Network) (CR)

ARCnet Topology is star and bus or a mixture. Cable type is RG-62 A/U coaxial (93 ohm), UTP or fiber-optic. A network can use any combination of this media. Connectors used include BNC, RJ-45, and others. It passes tokens passing for media access. Maximum segment length is 600 meters with RG-62 A/U, 121 meters with UTP, 3485 meters with fiber-optic, and 30 meters from a passive hub. It may use active and passive hubs. The specification is ANSI 878.1. It can have up to 255 nodes per network. The speed is 2.5 Mbps. ARCnet Plus has operating speeds approaching 20Mbps.

Signals are broadcast across the entire network with computers processing only signals addressed to them. ARCnet tokens travel based on a station identifier (SID) which each computer has. Each network card has a DIP switch used to set the SID with an address between 1 and 255. Signals are generally sent from the lowest numbered station to the next until they wrap around back to SID of 1. To determine non-existent stations, the station with the lowest ID indicates it has the token and begins querying IDs of higher value until it gets a response. Then the next computer does the same until the original station is queried. This procedure is done when a station is added or removed from the network or when the network is originally started. How does the network know when a station has been added or removed? How is the lowest numbered SID identified? Addresses assignment based on proximity causes the network to operate more efficiently.

The acronym SID is used for a station identifier with regard to ARCnet, but as used in the Windows NT and Windows 95 operating systems, it refers to the security identification number of a user or group.

Troubleshooting

Card default address is 0. Bus topology cannot support more than 10 nodes per segment.

Characteristics Summary

  • Topology - star-bus.
  • Cable - 93 ohm coaxial or fiber.
  • Speed - 2.5/20 Mbps.
  • Maximum segment length - 600 meters with RG-62, 121 meters with UTP, 3485 meters with fiber.
  • Media access - Token passing.
  • Maximum nodes on the network - 255.