Appendix: NetBIOS protocols in IBM PC Network

The NetBIOS interface was developed by Sytec Inc. (now Hughes LAN Systems) for International Business Machines Corporation (IBM) in 1983. This operated over proprietary Sytec protocols on IBM's PC Network.

Information is provided here for reference although these protocols have now been superceeded by the NetBIOS Frames protocol running over Token Ring or Ethernet etc.

Name Management Frames in IBM PC Networks

In the IBM PC Network name management is performed by the Name Management Protocol which consists of the following packet types:

Name Claim / Name Cancel Packet
A single octet indicates whether the packet is used to claim a name (value 0x10) or release a name (value 0xA0)
Name Claim Response Packet
This packet is used to indicate that the name is already in use.

Details of packet structures for Name Management in IBM PC Networks are given in the Comparison of NetBIOS protocols in IBM PC Network

Name Claim / Name Cancel Packet in IBM PC Network

From "Inside NetBIOS":

Name Claim / Name Cancel Packet:

Field Length Description

  1. Start 1 Start Deliminator value 0x7E
  2. Destination 6 Destination Address
  3. Source 6 Source Address
  4. Length 2 Length of packet
  5. value 2 value set to 0x5000
  6. Function 1 10h for Name Claim, 0xA0 for Cancel
  7. Accept 1 Number of packets willing to accept
  8. Connection id 2 Connection id
  9. value 2 value set to 0x0202
  10. Undefined 2 value of two octets undefined
  11. value 2 value set to 0x0400
  12. Undefined 4 value of four octets undefined
  13. value 2 value of 0x10XX
  14. value 4 value of 0x0000
  15. Dest Name 16 ASCII Destination NetBIOS name
  16. Previous Connection id 2 Previous Connection id
  17. Retransmit Count 2 Retransmition Count
  18. Source Node Connection id 2 Source Node Connection id
  19. Destination id 6 Destination id
  20. Source id 6 Source id
  21. Prev Node id 6 Previous Node id
  22. CRC 4 Cyclic Redundancy Check
  23. End of Frame 1 End of frame marker value of 0x7E

Name Claim Response Packet in IBM PC Network

Name Claim Response Packet:

Field Length Description

  1. Start 1 Start Deliminator value 0x7E
  2. Destination 6 Destination Address
  3. Source 6 Source Address
  4. Length 2 Length of packet
  5. value 2 value set to 0x4000
  6. value 1 value set to 0x30
  7. Accept 1 Number of packets willing to accept
  8. Connection id 2 Connection id
  9. Undefined 2 value of two octets undefined
  10. Reason packet NAK 1 Reason why packet not acknowledged
  11. Undefined 1 value of octet undefined
  12. value 2 value set to 0x0400
  13. Undefined 4 value of four octets undefined
  14. value 2 value of 0x10XX
  15. value 4 value of 0x0000
  16. Dest Name 16 ASCII Destination NetBIOS name
  17. Dest Node Connection id 2 Destination node connection id
  18. CRC 4 Cyclic Redundancy Check
  19. End of Frame 1 End of frame marker value of 0x7E

Datagram Packet in IBM PC Network

Details of packet structures for User Datagram Protocol in IBM PC Networks are given in the Comparison of NetBIOS protocols in IBM PC Network

User Datagram Protocol Packet in IBM PC Network

From "Inside NetBIOS":

User Datagram Protocol Packet:

Field Length Description

  1. Start 1 Start Deliminator value 0x7E
  2. Destination 6 Destination Address
  3. Source 6 Source Address
  4. Length 2 Length of packet
  5. value 2 value set to 0x5100
  6. value 2 value set to 0x0100
  7. value 2 value set to 0x0001
  8. value 2 value set to 0x1010
  9. value 2 value set to 0x0000
  10. Source Name 16 ASCII Source NetBIOS name
  11. Dest Name 16 ASCII Destination NetBIOS name
  12. Data variable data
  13. Retransmit Count 2 Retransmition Count
  14. Source Node Connection id 2 Source Node Connection id
  15. Destination id 6 Destination id
  16. Source id 6 Source id
  17. Prev Node id 6 Previous Node id
  18. CRC 4 Cyclic Redundancy Check
  19. End of Frame 1 End of frame marker value of 0x7E

NetBIOS Session Management Protocol in IBM PC Networks

Details of packet structures for NetBIOS Session Management in IBM PC Networks are given in the Comparison of NetBIOS protocols in IBM PC Network

Session Request Packet in IBM PC Network

From "Inside NetBIOS":

Session Request Packet :

Field Length Description

  1. Start 1 Start Deliminator value 0x7E
  2. Destination 6 Destination Address
  3. Source 6 Source Address
  4. Length 2 Length of packet
  5. value 2 value set to 0x0040
  6. Function 1 value 0x00-0x07=No poll 0x80-0x0F=Send Return Pkt
  7. Accept 1 Number of packets willing to accept
  8. Connection id 2 Connection id
  9. Sess seq no 1 Sess seq no
  10. ACK Seq No 1 ACK Seq No
  11. value 2 value set to 0x0001
  12. Response packet size 2 Response packet size
  13. value 4 value of 0x0000
  14. value 4 value of 0x1010
  15. Source Name 16 ASCII Source NetBIOS name
  16. Dest Name 16 ASCII Destination NetBIOS name
  17. Dest Connection id 2 Dest Connection id
  18. CRC 4 Cyclic Redundancy Check
  19. End of Frame 1 End of frame marker value of 0x7E
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