The DLC Protocol

The DLC Protocol and OSI Model

PC Webopedia

DLC - Data Link Control (the second lowest layer in the OSI Reference Model. Every network interface card (NIC) has a DLC address or DLC identifier (DLCI) that uniquely identifies the node on the network. Some network protocols, such as Ethernet and Token-Ring use the DLC addresses exclusively. Other protocols, such as TCP/IP, use a logical address at the Network Layer to identify nodes. Ultimately, however, all network addresses must be translated to DLC addresses. In TCP/IP networks, this translation is performed with the Address Resolution Protocol (ARP). AKA, ARP is used to translate the DLC addresses on network interface cards (NICs) into TCP/IP addresses. For networks that conform to the IEEE 802 standards (e.g., Ethernet ), the DLC address is usually called the Media Access Control (MAC) address.

Windows NT Help

DLC - DLC protocol is used primarily to access IBM mainframe computers. Example, Microsoft SNA Server for Windows NT uses the DLC protocol device driver when communicating with mainframes on the token ring interface. DLC is also used to connect to printers (HP JetDirect) that are connected directly to a LAN, rather than to a specific computer. DLC allows Windows NT computers to connect to IBM mainframes using 3270 emulators. You can also connect to IBM AS/400 computers using 5250 emulators. DLC works with either token ring or ethernet media access control (MAC) drivers. DLC protocol works with Windows NT-based programs and with MS-DOS-based and 16-bit Windows-based programs.

Install DLC to

Connect to SNA (Systems Network Architecture) gateways
Connect to network-attached printers, such as HP JetDirect. Client computers sending print jobs to a network printer DO NOT need the DLC protocol installed. Only the Print Server communication directly with the printer needs to have DLC installed.
For Remoteboot Service. On Windows NT, Remoteboot Service requires DLC to be installed on the Windows NT Server

No Properties are available for this protocol on Windows NT. DLC is bridgeable but not routable protocol and may be bound to multiple network adapters.

Troubleshooting DLC Protocol

Trying to connect to a DLC printer and can't

possible that another jerk is connected to the printer in "continuous connection mode."

Conceptual OSI Model (PC Webopedia)

Layer	Name	Function

7	Application Layer	Program-to-program communication.
6	Presentation Layer	Manages data representation conversions. For example, the Presentation Layer would be responsible for converting from EBCDIC to ASCII.
5	Session Layer	Responsible for establishing and maintaining communications channels. In practice, this layer is often combined with the Transport Layer.
4	Transport Layer	Responsible for end-to-end integrity of data transmission.
3	Network Layer	Routes data from one node to another.
2	Data Link Layer	Responsible for physical passing data from one node to another.
1	Physical Layer	Manages putting data onto the network media and taking the data off.