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Q102450: Windows NT Uses DLC for IBM Connectivity and Network Printing

Article: Q102450
Product(s): Microsoft Windows NT
Version(s): 2000,3.1,4.0
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 08-AUG-2001

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The information in this article applies to:

- Microsoft Windows 2000 Advanced Server 
- Microsoft Windows 2000 Server 
- Microsoft Windows NT Workstation versions 3.1, 4.0 
- Microsoft Windows NT Server versions 3.1, 4.0 
- Microsoft Windows NT Advanced Server, versions 3.1, 4.0 
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SUMMARY
=======

Data link control (DLC) is a transport protocol defined by IBM. It is mainly
used to communicate with IBM mainframes and minicomputers, typically model 3270
or AS/400 machines. In addition, Windows NT also uses DLC to communicate with
network printers such as the Hewlett-Packard (HP) LaserJet 4 Si.

MORE INFORMATION
================

DLC works with Token Ring (802.5) or Ethernet (802.3) NDIS (network driver
interface specification) MAC (media access control) drivers.

DLC is available to 32-bit Windows NT-based programs and 16-bit MS-DOS-based and
Windows-based programs. Since there are few 32-bit 3270 emulators available, DLC
is typically by 16-bit 3270 and 5250 (AS/400) emulators. These are
character-mode or graphics-mode MS-DOS-based programs or Windows-based programs
that communicate with an IBM mainframe using 3270 terminal emulation.

The following 16-bit 3270 and 5250 emulation programs should work normally with
Windows NT:

For IBM 3270:

  AttachMate Extra! for Windows v 3.3, 3.4 and 3.5
  AttachMate Extra! for MS-DOS v 2.23
  IBM PC/3270 v 2.0 for Windows
  IBM PC/3270 v 2.0 for MS-DOS
  IBM PC/3270 v 3.0 for Windows
  IBM PC/3270 v 3.0 for MS-DOS
  Eicon Access for Windows v 3.11, 3.14
  Dynacomm Elite/3270

For IBM 5250:

  IBM PCS v 2.0
  NSA Elite/400

Windows NT also uses DLC to communicate with network printers, such as the HP
LaserJet 4 Si. Such printers have a network interface card (NIC) that contains a
MAC and a DLC protocol stack. Print jobs are sent to these printers as DLC-level
frames over the network, instead of over the parallel port. The advantages of
such printer setups are increased print job download speed and the ability to
have the printer physically distant from its server. Note that even though the
printer has the ability to receive print jobs over the network, with Windows NT,
it is usually controlled by a print server that has sole control of the network
connection to the printer (meaning that other computers cannot connect to the
printer, even if they know the network address of the printer). This is because
DLC uses service access points (SAPs) and only one is available for connections.
Once a remote computer has connected to the SAP, subsequent connect requests are
denied at the printer.

Additional query words: adapter prodnt PROT005

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Keywords          : kbnetwork 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbwin2000AdvServ kbwin2000AdvServSearch kbwin2000Serv kbWinNTW310 kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbWinNTS310 kbWinNTAdvSerSearch kbWinNTAdvServ400 kbWinNTAdvServ310 kbwin2000ServSearch kbwin2000Search kbWinNTS310search kbWinNT310Search kbWinNTW310Search kbWinAdvServSearch
Version           : :2000,3.1,4.0

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