DLC Driver Parameters in the Registry

When an adapter is opened for the first time, the DLC protocol driver writes default values into the Windows registry for that adapter. These values control the various timers that DLC uses, whether DIX frames should be used over an Ethernet link, and whether bits in a destination address should be swapped (used) when traversing a bridge that swaps destination addresses.

The timer entries in the registry are supplied because program-supplied timer values might not be sufficient. There are three timers used by DLC link communication:

  • T1 — The response timer.

  • T2 — The acknowledgment delay timer.

  • Ti — The inactivity timer.



Do not use a registry editor to edit the registry directly unless you have no alternative. The registry editors bypass the standard safeguards provided by administrative tools. These safeguards prevent you from entering conflicting settings or settings that are likely to degrade performance or damage your system. Editing the registry directly can have serious, unexpected consequences that can prevent the system from starting and require that you reinstall Windows 2000. To configure or customize Windows 2000, use the programs in Microsoft Management Console (MMC) or Control Panel whenever possible.

Each timer is split into two groups, TxTickOne and TxTickTwo , where x represents "1," "2," or "i." Typically, these timer values are set when a program opens an adapter or creates a Service Access Point. The registry contains entries used to modify timer values. Registry entries for DLC are found in the following location:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DLC \Parameters\< Adapter Name >

When you edit the value of a timer entry, the change takes effect only when the adapter is re-opened.