Copyright: ® 1993 Microsoft Corporation


Help Contents
Microsoft® Data Link Control Protocol for Windows™ for Workgroups

Version 1.0a

For the Microsoft Windows for Workgroups Operating System with Integrated Networking

Microsoft Corporation

Information in this document is subject to change without notice and does not represent a commitment on the part of Microsoft Corporation. The software described in this document is furnished under a license agreement or nondisclosure agreement. The software may be used or copied only in accordance with the terms of the agreement. It is against the law to copy the software on any medium except as specifically allowed in the license or nondisclosure agreement.  No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, or storage retrieval systems, for any purpose other than the purchaser's personal use, without the express written permission of Microsoft Corporation.

© 1993 Microsoft Corporation. All rights reserved.  U.S. Patent No. 4955066

Microsoft® Data Link Control Protocol for Windows™ for Workgroups Software

License Agreement

Installing the Software

For Support

Introduction

Trademarks

Before You Begin

How to Use This Manual

Documentation Conventions

Finding Further Information

Overview of Microsoft DLC

Overview

Installing and Using Microsoft DLC

Overview

Installing Microsoft DLC

Configuring DLC

Microsoft DLC Protocol Parameters

PROTOCOL.INI Parameters

Overview

Required PROTOCOL.INI Parameters

Optional PROTOCOL.INI Parameters

DLC Error Messages

Overview

Error Messages


License Agreement

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MICROSOFT LICENSE AGREEMENT

Microsoft Data Link Control Protocol for Windows for Workgroups

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Installing the Software

If you have installed a previous version of the Microsoft DLC protocol for Windows for Workgroups (such as the MS-DLC support offered with LAN Manager version 2.2), be sure to remove it using the Network section of Windows Setup before running the installation procedure described in the section entitled "Installing and Using Microsoft DLC."

See the READDLC!.TXT file provided on the Microsoft Data Link Control Protocol for Windows for Workgroups disk (also copied in the WINDOWS directory when the Data Link Control Protocol is installed) for additional information on installing Microsoft Data Link Control Protocol for Windows for Workgroups.

Related Topics:

Installing Microsoft DLC


For Support

Support for Microsoft Data Link Control Protocol for Windows for Workgroups is not available from the standard Windows for Workgroups Product Support Services phone line.  If you have questions, please contact your Microsoft Solution Channel member.  Support for this product is also available through Microsoft's fee-based support plans.  For information locating a Solutions Channel member near you or about Microsoft's support options, call Microsoft Inside Sales in the United States at (800) 227-4679 or your local Microsoft subsidiary.


Trademarks

Microsoft, MS, and MS-DOS are registered trademarks and Windows is a trademark of Microsoft Corporation in the USA and other countries.

DCA and IRMA are registered trademarks of Digital Communications Associates, Inc.

DynaComm is a registered trademark of Future Soft Engineering, Inc.

IBM is a registered trademark of International Business Machines Corporation.

Microcom is a registered trademark of Microcom Systems, Inc.

Rumba and Wall Data are registered trademarks of Wall Data Incorporated.


Before You Begin

This manual describes how to install, configure, and troubleshoot the Microsoft Data Link Control (DLC) Protocol on a workstation running the Microsoft® Windows™ for Workgroups operating system with integrated networking.

This manual assumes that you are familiar with the Windows for Workgroups operating system. If you are not familiar with this product or you are having problems with your workstation configuration, refer to the documentation set that came with the operating system.


How to Use This Manual

Turn to the part that contains the information you need.

"Overview of Microsoft DLC"

Provides an overview of the Microsoft DLC protocol.

"Installing and Using Microsoft DLC"

Describes the process for installing and using the Microsoft DLC protocol on a workstation.

"Configuring Microsoft DLC"

Describes the process for configuring the Microsoft DLC protocol and lists all of the available parameters that can be changed via the Network option in the Control Panel.

"PROTOCOL.INI Parameters"

Contains detailed information about all of the available parameters that can be changed in the PROTOCOL.INI file.

"Error Messages"

Lists error messages and recovery procedures for the Microsoft DLC protocol.


Documentation Conventions

This manual uses several type styles and special characters.

Documentation Type Styles and Special Characters

Convention	Use
bold	Represents commands, command options, and file entries. Type bold words exactly as they appear (for example, net use).
italic	Introduces new terms and represents variables. For example, the variable computername indicates that you type the name of a workstation or a server.
monospace	Represents examples, screen displays, and error messages.
ALL UPPERCASE	Represent filenames and paths. You can, however, type entries in uppercase or lowercase letters, or a combination of the two.
SMALL CAPITALS	Represent key names (for example, CTRL, ENTER, and F2).


Finding Further Information

This manual is written for users of the Microsoft Windows for Workgroups operating system. If you are integrating with a LAN Manager local area network, you might want to refer to the following manuals.

Microsoft LAN Manager Installation and Configuration Guide

Provides information about installing LAN Manager software, about the network device drivers used with LAN Manager, and about configuring workstations and servers.

Microsoft LAN Manager Administrator's Guide

Provides step-by-step instructions for administering a LAN Manager network.

Microsoft LAN Manager Administrator's Reference

Provides reference information about LAN Manager commands and utilities for MS® OS/2® computers, and about the LAN Manager program directory and initialization files.


Overview of Microsoft DLC - Overview
Overview

This chapter introduces you to the Microsoft Data Link Control (DLC) protocol for the Microsoft Windows for Workgroups operating system with integrated networking. For information on how to install Microsoft DLC on your Windows for Workgroups workstation, see the section entitled "Installing and Using Microsoft DLC."

In relation to the OSI model, the Microsoft DLC protocol provides a data link layer interface to the network. The data link layer is responsible for point-to-point transmission of data.

Figure 1.  Network layers and Windows for Workgroups

Terminal emulation applications call the Microsoft DLC protocol with the Int 0x5C (NetBIOS) interrupt vector. The Microsoft DLC protocol communicates only through the terminal emulation applications; it does not use the Windows for Workgroups network redirector to communicate with the network. It does not have a NetBIOS interface. The Microsoft DLC protocol can co-exist with other protocols. The Microsoft DLC protocol conforms to the Network Driver Interface Specification (NDIS) 2.0.


Installing and Using Microsoft DLC - Overview
Overview

This chapter describes the process for installing and using the Microsoft DLC protocol on a workstation running the Microsoft Windows for Workgroups operating system with integrated networking.

You should have successfully installed the Windows for Workgroups operating system on your workstation. If this is not the case, or you are having problems with your configuration, refer to your Windows for Workgroups documentation.


Installing Microsoft DLC

Before installing the Microsoft DLC protocol, make sure the Network Setup application is not running.

To install the Microsoft DLC protocol on a Windows for Workgroups workstation

1.	Run Windows Setup from the Main program group and select Change Network Settings from the Options menu, or run Network Setup from the Network program group.  The Network Setup dialog box appears:

Figure 1.    Network Setup dialog box used to install network drivers

2.	Choose the Drivers... button. The Network Drivers dialog box appears:

Figure 2.    Network Drivers dialog box used to add additional protocols

3.	In the Network Driver list box, select the adapter on which you want to use Microsoft DLC.

4.	Choose the Add Protocol... button. The Add Network Protocol dialog box appears.

Figure 3.   The Add Network Protocol dialog box, accessible through the Network Setup application.

5.	Select the Unlisted or Updated Protocol option from the list of available protocols and then choose OK.

The Install Driver dialog box appears.

6.	Insert the Microsoft Data Link Control Protocol for Windows for Workgroups disk in drive A (or drive B, as appropriate).

7.	In the Install Driver dialog box, type A: for the location of the Microsoft DLC for Windows for Workgroups disk, then choose OK.

The Unlisted or Updated Protocol dialog box appears.

8.	Select Microsoft DLC.

9.	Choose OK.

The Microsoft DLC for Windows for Workgroups protocol software is copied to your workstation.

11.	If Microsoft DLC is not listed as the default protocol at the bottom of the Network Drivers dialog box, highlight Microsoft DLC and click the Set As Default Protocol button.

12.	Choose OK to close any dialog boxes that may be open, and re-boot your system for the changes to take effect.

To customize the configuration of the DLC protocol, continue with the next procedure.

Related Topics:

Sample Installed Configuration


Sample Installed Configuration

Once you have successfully installed the Microsoft DLC protocol for Windows for Workgroups on a workstation, the configuration files will look similar to the following. (No changes are made to the CONFIG.SYS file.)

AUTOEXEC.BAT

C:\WINDOWS\NET START

C:\WINDOWS\SMARTDRV.EXE

C:\WINDOWS\NET INIT

C:\WINDOWS\MSDLC.EXE

PROMPT $p$g

PATH C:\WINDOWS;C:\DOS;

SET TEMP=C:\WINDOWS\TEMP

Note:	If you are updating from a previous version of the Microsoft DLC protocol and had the MSDLC driver loaded high, you may need to add the loadhigh (LH) parameter to the MSDLC.EXE line again.

PROTOCOL.INI

[network.setup]

version=0x3101

netcard=ms$elnk16,1,MS$ELNK16,1

transport=msdlc,MSDLC

transport=ms$netbeui,MS$NETBEUI

lana0=ms$elnk16,1,msdlc

lana1=ms$elnk16,1,ms$netbeui

[protman]

DriverName=PROTMAN$

PRIORITY=MS$NETBEUI

[MS$ELNK16]

DriverName=ELNK16$

[MS$NETBEUI]

DriverName=netbeui$

SESSIONS=10

NCBS=32

BINDINGS=MS$ELNK16

LANABASE=1

[MSDLC]

xstations1=0

xstations0=0

stations=20

saps=3

xsaps1=0

xsaps0=0

swap=1

usedix=0

DriverName=MSDLC$

BINDINGS=MS$ELNK16


Configuring DLC

This section describes the process for configuring the Microsoft DLC protocol (once you have installed it on your workstation). The following section lists all of the available parameters that can be changed via the Microsoft DLC Configuration dialog box. In most cases, you do not need to change any parameter values when the Microsoft DLC protocol is installed. If, however, you want to tune the Microsoft DLC protocol yourself, follow the procedures in this section, and refer to the next section for information on each of the available settings.

To configure the Microsoft DLC protocol on a workstation

1.	Double-click the Network Setup icon in the Network program group.

The Network Setup dialog box appears.

2.	In the Network Driver list box, select the adapter on which you previously installed Microsoft DLC.

3.	Choose the Drivers... button.

The Network Drivers dialog box appears.

4.	Select the Microsoft DLC protocol from the Network Drivers list box.

5.	Choose the Setup... button.

A message box like the following displays, letting you know that for most users, the default DLC protocol settings are suitable. Therefore you may not need to change any of the DLC parameters.

Figure 5.   DLC parameter message box

Choose OK to continue configuring the DLC parameters, or choose Cancel to return to the Network Drivers dialog box.

If you choose OK, the Microsoft DLC Configuration Dialog box appears.

Figure 6.  Microsoft DLC Configuration dialog box

6.	Update the values for the parameters you want to change.

Tip	When your cursor is on a particular field, you can use the Reset button to reset that value to its default. You can also use the Reset All button to reset all values to their defaults.

For detailed information on each of the settings in the Microsoft DLC Configuration dialog box, see the following topics in this chapter.

The Microsoft DLC for Windows for Workgroups configuration program will check the validity of the values you enter. or other Microsoft DLC parameters that can be modified, by directly editing the PROTOCOL.INI file, see "PROTOCOL.INI Parameters."

7.	When you are through making changes to the Microsoft DLC Configuration dialog box, choose OK.

8.	In the Network Drivers dialog box, choose the Close button.

9.	In the Network Setup dialog box, choose OK.

A message box appears notifying you that your startup files have been modified. Choose OK.

10.	A message box appears notifying you that you must reboot for changes made to your system to take effect.

To first make any additional changes to system files before rebooting your workstation, choose the Continue button.

Alternately, to reboot your workstation and put the Microsoft DLC protocol into effect, choose the Restart Computer button.

Note	You must reboot your workstation for the Microsoft DLC protocol to take effect.


Microsoft DLC Protocol Parameters

The following Microsoft DLC protocol parameters can be updated from the Microsoft DLC Configuration dialog box.

use DIX

Sets the frame format. By default, this value is disabled.

Disable this value for 802.3 Ethernet format. Enable this value for Ethernet DIX 2.0 (Ethertype 0x80D5) format. (Ethernet DIX frames have an extra type-field.)

swap

Turns on address bit-swapping when it is enabled and Microsoft DLC is bound to an Ethernet driver. By default, this value is enabled.

If you previously used the IBM DXME0MOD.SYS driver successfully, use the following table to map its xmit_swap parameter to Microsoft DLC parameters.

DXME0MOD.SYS xmit_swap	Microsoft DLC swap	Microsoft DLC Use DIX
0	enable	disable
1	enable	enable
2	disable	disable
3	disable	enable
saps

Indicates the number of SAPs that can be opened simultaneously. The range for SAPs is 1 to 255 inclusive. The default is 3.

For a description of SAPs, see the IBM Local Area Network Technical Reference. For more information about adjusting the SAPs value, see the stations parameter.

stations

Indicates the number of link stations that can be opened simultaneously. The range for stations is 1 to 255 inclusive. The default is 20.

Each application requires a certain number of SAPs and stations. Because each SAP or station takes up memory, you should provide just enough for your application to run. The following table provides some examples of the number of SAPs and stations needed by specific applications.

Application	SAPs	Stations
DCA® IRMA® Workstation for DOS	3	10
Dynacomm® Elite for DOS	2	4
Eicon Access version 3.11	1	1
Attachmate Extra for DOS version 2.23	2	2
Attachmate Extra for Windows version 3.3	2	8
IBM® PC 3270 version 2 for DOS	2	20
IBM PC 3270 version 2 for Windows	2	20
IBM Personal Communication Support (PCS)	1	3
Microcom® Relay Gold 5.00 (for DOS)	2	2
Microcom Relay Gold 5.0b (for Windows)	2	2
Wall Data® Rumba® version 3.1	2	1
xsaps0

Update the value for this parameter if you need to run more than one DLC application. The range for xsaps0 is 0 to 127 inclusive. The default is 0.

Specifying a value for this parameter causes this value to be compared to the maximum value for SAPs (specified by the application program) during the dir.open.adapter call for adapter #0, and the larger of the two is used. If the sum xsaps0 + xsaps1 exceeds the value specified for SAPs, SAPs will automatically be increased to the value of xsaps0 + xsaps1.

For example, if you are running two DLC applications and each requires two SAPs, set xsaps0 to 4. When the first DLC application issues the dir.open.adapter call, it will ask for two SAPs but will get four SAPs because of the xsaps0 parameter. This way, the second DLC application receives enough SAPs to run.

xsaps1

Similar to xsaps0, but for adapter #1. The range for xsaps1 is 0 to 127 inclusive. The default value is 0.

xstations0

Similar to xsaps0, but used for changing the number of link stations, rather than the number of SAPs. The range for xstations0 is 0 to 127 inclusive. The default is 0.

If the sum of xstations0 + xstations1 exceeds the value for stations, stations will automatically be increased to the value of xstations0 + xstations1.

xstations1

Similar to xstations0, but for adapter #1. The range for xstations1 is 0 to 127 inclusive. The default is 0.


PROTOCOL.INI Parameters - Overview
Overview

The Microsoft DLC for Windows for Workgroups protocol settings are acceptable for everyday users. The graphical installation and configuration process should allow most users to configure their systems effectively. If, however, you want to fine-tune options, you can change values in the Windows for Workgroups PROTOCOL.INI file with a text editor. You must reboot for the changes to take effect. This appendix documents all of the available parameters that can be changed, as needed, in the [msdlc_xif] section of the PROTOCOL.INI file.

Caution:	Adjusting any PROTOCOL.INI parameters can severely degrade or impede system performance. Be sure that you fully understand the effect(s) your changes will have. You should back up your PROTOCOL.INI file before making any changes. In the event that a change "breaks" your system, revert to the defaults shown in the following tables or use your backup settings.

Note that many of the parameters described in this appendix can be configured using the Network section in Windows Setup, as described in the section "Configuring Microsoft DLC."  Using the Network setup is the recommended method for updating values because of the validation feature this method provides.  No validation feature is provided when you directly edit the PROTOCOL.INI file.

The default Microsoft DLC for Windows for Workgroups protocol settings are acceptable for most users. The graphical installation and configuration process should allow most users to configure their systems effectively. If, however, you want to fine-tune options, you can change values in the Windows for Workgroups PROTOCOL.INI file with a text editor. You must reboot for the changes to take effect. This appendix documents all of the available parameters that can be changed, as needed, in the [msdlc_xif] section of the PROTOCOL.INI file.


Required PROTOCOL.INI Parameters

The following table summarizes the required entries and their default values in the [msdlc_xif] section of the PROTOCOL.INI file.

Required entry	Units	Range	Default
bindings	drivers	—	no default
drivername	—	—	msdlc$
transport	drivers	—	msdlc
lana#	drivers	—	no default
Entries in the [network.setup] section of the PROTOCOL.INI file have the following meanings:

lana#

Identifies the binding between the network adapter and the network protocol, as configured during installation.

transport

Specifies the name of the network transport driver protocol, in this case msdlc.  This required value is set during installation.


Optional PROTOCOL.INI Parameters

The following table summarizes the possible entries and values in the [msdlc] section of the PROTOCOL.INI file.

Entry	Units	Range	Default
adaptrate	milliseconds	0 - 65535	0
bufqelements	buffers	1- 2048	64
class1timeout	seconds	0- 65535	120
commands	descriptors	1- 255	24
denysaps	—	0x02- 0xFE	0xF0
ipackets	packets	1- 1000	24
looppackets	packets	1- 1000	2
maxgroup	packets	1- 126	0
maxin	packets	1- 127	1
maxmember	packets	1- 127	0
maxout	packets	1- 127	12
msdlcretries	retries	1- 65535	8
saps	—	1- 255	3
stacksize	bytes	512- 4096	2048
stations	—	1- 255	20
swap (Ethernet only)	—	0- 1	1
t1_tick_one	40 milliseconds	1- 255	5
t1_tick_two	40 milliseconds	1- 255	25
t2_tick_one	40 milliseconds	1- 255	1
t2_tick_two	40 milliseconds	1- 255	10
timers	timers	1- 255	12
ti_tick_one	40 milliseconds	1- 255	25
ti_tick_two	40 milliseconds	1- 255	125
trxbuffers	buffers	0- 32	0
trxbufsize	bytes	0- 16000	0
uipackets	packets	2- 300	16
usedix (Ethernet only)	—	0- 1	0
windowerrors	errors	0- 10	0
xsaps0	—	0- 127	0
xsaps1	—	0- 127	0
xstations0	—	0- 127	0
Entries in the [msdlc] section of the PROTOCOL.INI file have the following meanings.

adaptrate

Specifies the time in milliseconds between runs of the adaptive window algorithm. For each link, the Microsoft DLC driver uses the algorithm to match the maxin and maxout values with the remote station's values as closely as possible. The algorithm also considers the conditions of the link (such as adapter receiver buffers, load, and so on).

When no dropped packets are detected, the adaptive window algorithm increases the send window (see maxout). If dropped packets are detected (more than the value of windowerrors), the algorithm decreases the send window. Similarly, the algorithm adjusts the receive window based on the time-out expiration of the t2 timer.

Adaptrate should be large in relation to t1 and t2 — usually above one second— but it can be smaller than ti.

A value of 0 turns off the algorithm, meaning that the maxin and maxout values never change.

bindings

Names the driver(s) to which Microsoft DLC binds. The Microsoft DLC driver can bind to as many as two network adapter drivers. Use commas to separate the driver names.

bufqelements

Specifies the total number of buffers that can be pooled in the driver at one time. This is not a per-pool limit, but a limit across all pools.

class1timeout

Specifies the length of time a network adapter driver should spend trying to send a UI frame before giving up and freeing the resources.

commands

Specifies the number of CCB descriptors to allocate for managing CCBs submitted to the Microsoft DLC driver. Specifies the number of commands pending simultaneously. The equivalent entry in the Microsoft NetBEUI protocol is called ncbs.

denysaps

Specifies a list of SAP values that can not be opened on the driver. The NetBIOS SAP (0xF0) is denied by default. To allow the NetBIOS SAP, set no value for denysaps.

drivername

Identifies the driver name of the network device driver. The base portion of the driver's filename, plus a dollar sign, is the drivername. The Microsoft DLC drivername is msdlc$.

ipackets

Specifies the number of I-frame packet descriptors that the Microsoft DLC driver can use to build DLC frames.

load

Specifies whether to load Microsoft DLC into conventional or high memory. This required value is set during installation. You can change where Microsoft DLC is loaded later by editing this entry. The next time Microsoft DLC is loaded, the new value will take effect.

looppackets

Specifies the number of frames to be looped back at one time. Packets are used when the workstation sends a message to itself.

maxgroup

Specifies the maximum number of Group SAPs that can be opened simultaneously.

The default values for maxgroup and maxmember are zero because most applications do not use Group SAPs. Increase these values if your applications use Group SAPs.

maxin

Specifies the number of packets to be received before sending an acknowledgment. This number is often called the receive window.

When the adaptrate entry is present and has a value of zero, the maxin value is not dynamically adjusted. Otherwise, the Microsoft DLC driver adjusts the maxin value as described in the adaptrate entry in this section.

maxmember

Specifies the maximum number of SAPs that can belong to each Group SAP.

The default values for maxgroup and maxmember are zero because most applications do not use Group SAPs. Increase these values if your applications use Group SAPs.

maxout

Specifies the number of packets to send before expecting an acknowledgment. This number is often called the send window.

When the adaptrate entry is present and has a value of zero, the maxout value is not dynamically adjusted. Otherwise, the Microsoft DLC driver adjusts the maxout value as described in the adaptrate entry in this section.

msdlcretries

Specifies the number of transmission retries that Microsoft DLC makes before assuming that the receiver is not responding. You can lower the value of this entry on a highly reliable network, where few packets are dropped. Raise the value if the network is prone to dropping packets.

The types of network adapters on the network affect reliability because some have limited buffering capabilities and might drop packets because of a buffer-resource problem.

saps

Indicates the number of SAPs that can be opened simultaneously. For a description of SAPs see the IBM Local Area Network Technical Reference. For more information about adjusting the saps entry, see the stations entry.

stacksize

Indicates the size, in bytes, of the Microsoft DLC protocol's internal stack.

stations

Indicates the number of link stations that can be opened simultaneously.

Each application requires a certain number of SAPs and stations. Because each SAP or station takes up memory, you should provide just enough for your application to run. Here are some examples of the number of SAPs and stations needed by specific applications.

Application	SAPs	Stations
DCA IRMA Workstation for DOS	3	10
Dynacomm Elite for DOS	2	4
Eicon Access version 3.11	1	1
Attachmate Extra for DOS version 2.23	2	2
Attachmate Extra for Windows version 3.3	2	8
IBM PC 3270 version 2 for DOS	2	20
IBM PC 3270 version 2 for Windows	2	20
IBM Personal Communication Support (PCS)	1	3
Microcom Relay Gold 5.0b (for Windows)	2	2
Microcom Relay Gold version 5.0 (for DOS)	2	2
Wall Data Rumba version 3.1	2	1
If you do not know the number of SAPs and stations your application requires, and you want to minimize the memory usage of your terminal emulation applications, start with large values and gradually reduce them until the application no longer works.

The default is set to saps=3 and stations=20. This is more than enough for most Microsoft DLC applications.

swap

When Microsoft DLC is bound to an Ethernet driver, setting this parameter to 1 (enable) turns on address bit-swapping.

If you previously used the IBM DXME0MOD.SYS driver successfully, this is how to map its xmit_swap parameter to the Microsoft DLC driver's swap and usedix parameters.

DXME0MOD.SYS xmit_swap	Microsoft DLC swap	Microsoft DLC usedix
0	1	0
1	1	1
2	0	0
3	0	1
t1_tick_one

Sets the retransmission-timer "short tick" value in units of 40 milliseconds. This timer determines the delay before retransmitting a link-level frame if no acknowledgment is received.

The Microsoft DLC protocol uses three timers: t1 (retransmission), t2 (acknowledgment), and ti (inactivity). Each timer has a "short tick" rate and a "long tick" rate that individual commands use in determining timer values. A command such as dlc.open.sap specifies a timer value with a number range of 1 - 10 units of milliseconds.

When the number is in the range of 1 - 5 units of milliseconds, the actual timer value is:

(number selected) * (short-tick value) * 40 milliseconds

When the number is in the range of 6 - 10 units of milliseconds, the actual timer value is:

(number selected  - 5) * (long-tick value) * 40 milliseconds

Some network application programs adjust these timer entries automatically. The dlc.open.adapter command can override the default value.

t1_tick_two

Sets the retransmission-timer "long tick" value in units of 40 milliseconds. This timer determines the delay before retransmitting a link-level frame if no acknowledgment is received.

For an explanation of the relationship among timer entries, see the t1_tick_one entry in this section.

t2_tick_one

Sets the delayed-acknowledgment timer "short tick" value in units of 40 milliseconds. This timer determines the delay before acknowledging a received frame when the receive window has not been reached.

For an explanation of the relationship among timer entries, see the t1_tick_one entry in this section.

t2_tick_two

Sets the delayed-acknowledgment timer "long tick" value in units of 40 milliseconds. This timer determines the delay before acknowledging a received frame when the receive window has not been reached.

For an explanation of the relationship among timer entries, see the t1_tick_one entry in this section.

timers

Specifies the number of timers running at one time using the Microsoft DLC timer primitives.

ti_tick_one

Sets the inactivity-timer "short tick" value in units of 40 milliseconds. This timer determines how often an inactive link is checked to see whether it is still operational. For an explanation of the relationship among timer entries, see the t1_tick_one entry in this section.

ti_tick_two

Sets the inactivity-timer "long tick" value in units of 40 milliseconds. This timer determines how often an inactive link is checked to see whether it is still operational.

For an explanation of the relationship among timer entries, see the t1_tick_one entry in this section.

trxbuffers

Specifies the number of internal transmit buffers. Increase this value only if your configuration issues transmits containing more buffers than the network adapter driver can accept in one transfer call.

trxbufsize

Specifies the size of internal transmit and receive buffers. Increasing this value is required only when running applications that use Group SAPs or that issue transmits containing more buffers than the media access control driver can accept in one transfer call.

uipackets

Specifies the number of data descriptors to allocate for sending UIframes.

unload

Specifies how to unload Microsoft DLC from memory. This value should not be changed.

usedix (Ethernet only)

Sets the frame format. Set the value to 0 (the default, disable) for 802.3 Ethernet format. Set the value to 1 (enable) for Ethernet DIX 2.0 (Ethertype 0x80D5) format. (Ethernet DIX frames have an extra type-field.)

windowerrors

Specifies the number of dropped packets that the adaptive window algorithm allows before it decreases the send window. (For more information on the adaptive window algorithm, see the adaptrate entry in this section.) For example, if windowerrors has a value of 1, one packet can drop between runs of the algorithm without having any effect; if 2 packets drop, the algorithm decreases the send window.

Keep the value of windowerrors low for a lightly loaded network, and increase it for a heavily loaded network.

xsaps0

Update the value for this parameter if you need to run more than one DLC application. Specifying a value for this parameter causes this value to be compared to the maximum value for SAPs (specified by the application program) during the dir.open.adapter call for adapter #0, and the larger of the two is used. If the sum xsaps0 + xsaps1 exceeds the value specified for SAPs, SAPs will automatically be increased to the value of xsaps0 + xsaps1.

xsaps1

Similar to xsaps0, but for adapter #1.

xstations0

Similar to xsaps0, but used for changing the number of link stations, rather than the number of SAPs. If the sum of xstations0 + xstations1 exceeds the value for stations, stations will automatically be increased to the value of xstations0 + xstations1.

xstations1

Similar to xstations0, but for adapter #1.


DLC Error Messages - Overview
Overview

This appendix lists the error messages that might appear when running the Microsoft DLC protocol for the Windows for Workgroups operating system. Where appropriate, suggested recovery methods are provided for the error messages.

In most cases, these errors occur when the configuration files (PROTOCOL.INI, CONFIG.SYS, and AUTOEXEC.BAT) have been modified, by hand or by another application, and contain errors. If you prefer not to attempt to correct a file manually, you might want to reinstall the Microsoft DLC protocol on your Windows for Workgroups workstation.


Error Messages

DLC load failure

The Microsoft DLC protocol did not load. Check the message that preceded this one for information on what occurred and how to correct the problem.

DLC module not found in PROTOCOL.INI

The section containing the drivername=msdlc$ entry is missing from the PROTOCOL.INI file. Use the procedure in Chapter 2, "Installing and Using Microsoft DLC," to re-install the Microsoft DLC protocol.

No MAC drivers bound to the driver, unloading

No valid network adapter driver is bound to Microsoft DLC. Use the procedure in Chapter 2, "Installing and Using Microsoft DLC," to re-install the Microsoft DLC protocol.

Parameter settings exceed available memory

The total data memory usage exceeds 64K. Reduce memory usage on your workstation by decreasing the values of the following parameters in the [msdlc_xif] section of the PROTOCOL.INI file. (Refer to "Optional PROTOCOL.INI Parameters" for a list of ranges and default parameter settings.)

• bufqelements	• saps
• commands	• stacksize
• ipackets	• stations
• looppackets	• timers
• maxgroup	• trxbuffers
• maxmember	• uipackets
Protocol Manager could not be opened

The PROTMAN.EXE file was not loaded. Ensure that PROTMAN.EXE is loaded before Microsoft DLC in your startup files.

Protocol Manager would not supply config image

Make sure that the Protocol Manager is in dynamic mode, and that MSDLC.EXE is run with the load command in your startup files.

PROTOCOL.INI entry DENYSAPS contains invalid numbers or list is too long

Check that the value(s) specified for the denysaps entry in the [msdlc_xif] section of the PROTOCOL.INI file are valid, and that the list contains no more than 20 values. (Refer to "PROTOCOL.INI Parameters.")

PROTOCOL.INI keyword not recognized

An invalid entry has been detected in the [msdlc_xif] section of the PROTOCOL.INI file. Check the spelling of each entry.

PROTOCOL.INI parameter defined more than once

A parameter in the [msdlc_xif] section of the PROTOCOL.INI file is specified more than once. Remove the duplicate entries.

PROTOCOL.INI parameter format is incorrect

A list has been supplied to an entry that expects a single value. Find and correct the invalid entry in the [msdlc_xif] section of the PROTOCOL.INI file.

PROTOCOL.INI parameter has invalid type

A string is assigned to a parameter in the [msdlc_xif] section of the PROTOCOL.INI file that expects a number. Find and correct the invalid entry.

PROTOCOL.INI parameter is out of range

A value specified for a parameter in the [msdlc_xif] section of the PROTOCOL.INI file is not within the acceptable range. Verify all values in this section. (Refer to "Optional PROTOCOL.INI Parameters" for a list of valid ranges.)

Too many MAC drivers bound to the driver, unloading

More than two drivers are named on the bindings= entry in the [msdlc_xif] section of the PROTOCOL.INI file. Delete the excess entries.