Tuning NWLINK Registry Parameters

Last reviewed: January 14, 1998
Article ID: Q99745

The information in this article applies to:

Microsoft Windows NT Advanced Server version 3.1
Microsoft Windows NT operating system version 3.1
Microsoft Windows NT Workstation versions 3.5, 3.51, and 4.0
Microsoft Windows NT Server versions 3.5, 3.51, and 4.0

NWLink is an implementation of the IPX/SPX protocols popular in Novell NetWare networks. An additional module, NWNBLink, provides support for the Novell implementation of the NetBIOS protocol. This article is divided into the following sections:

NWNBLink Parameters (Microsoft Extensions to Novell NetBIOS)
NWNBLink Parameters (Novell NetBIOS or Microsoft Extensions)
IPX/SPX Parameters (Network Interface Cards/Token Ring)
IPX/SPX Parameters (Global)

CAUTION: Although you can modify all the parameters listed here in Registry Editor, the default values should rarely need to be changed. Any changes you make to these parameters can easily affect the performance of NWLink.

Note: All parameters are listed in the following format:

   <name> : <data type> : <default value> (valid range, units)

In Registry Editor, if no value is present, assume the default is being used. If you cannot find the parameter, you need to manually add it (choose Add Value from the Edit menu).

NWNBLink Parameters (Microsoft Extensions to Novell NetBIOS)

Registry path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services

               \NWNBLink\Parameters

The Microsoft Extensions to Novell NetBIOS are provided to enhance the performance of the traditional Novell NetBIOS protocol. NWNBLink can automatically detect whether or not it is talking to a Novell NetBIOS implementation that does not understand these extensions; if it is being misunderstood, NWNBLink falls back to the standard Novell NetBIOS protocol currently in use in Novell networks. Significant performance gains can be realized if the extensions are used (for example, if the NetBIOS conversation occurs between two Windows NT computers).

AckDelayTime : REG_DWORD : 250 (50-65535, milliseconds)

Determines the value of the delayed acknowledgment timer.

AckWindow : REG_DWORD : 2 (0-65535, frames)

Specifies the number of frames to receive before sending an acknowledgment. AckWindow is used as a clocking mechanism on networks in which the sender is networked on a fast LAN, but the receiver is networked on the other side using a slower link. By automatically forcing acknowledgments, the sender can keep sending frames continually. If both the sender and receiver are located on a fast link, you can set AckWindow to 0 to turn off sending an acknowledgment to the sender. Alternatively, NWNBLink can be set to dynamically determine whether to use the AckWindow parameter based on the setting of AckWindowThreshold.

AckWindowThreshold : REG_DWORD : 500 (0-65535, milliseconds)

Specifies the threshold value for the round trip time that defines when AckWindow is ignored. The round trip time is an estimate of how long it takes for a frame to be sent and received from a workstation. NWNBLink determines this estimate and uses it as a basis for determining whether it is necessary to send automatic acknowledgments. If AckWindowThreshold is set to 0, NWNBLink relies on the AckWindow entry.

EnablePiggyBackAck : REG_DWORD : 1 (0 - False or 1 - True)

Allows the receiver to piggyback acknowledgments. Piggybacking acknowledgments can occur when the receiver has detected the end of a NetBIOS message. When the sender and receiver are not participating in two-way NetBIOS traffic, you should set EnablePiggyBackAck to false. An example of one-way traffic is a stock update application, where a server constantly sends NetBIOS messages to clients, but the client does not need to respond.

If EnablePiggyBackAck is true but there is no back traffic, NWNBLink will wait the number of milliseconds determined by AckDelayTime before sending the acknowledgment, then it will turn off support for piggybacking acknowledgments. If the workstation at some point starts sending as well as receiving data, NWNBLink will turn support back on for piggybacking acknowledgments.

Extensions : REG_DWORD : 1 (0 - false or 1 - true)

Specifies whether to use NWNBLink extensions discussed in this section.

RcvWindowMax : REG_DWORD : 4 (1-49152, frames)

Specifies the maximum number of frames the receiver can receive at one time. The value specified by RcvWindowMax is sent to the sender during session initialization to give the sender an upper bound on the number of frames that can be sent at one time. (Related parameters: AckDelayTime, AckWindow, AckWindowThreshold, EnablePiggyBackAck, and RcvWindowMax.)

NWNBLink Parameters (Novell NetBIOS or Microsoft Extensions)

Registry path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services

               \NWNBLink\Parameters

The following parameters can be used to configure Novell NetBIOS or Microsoft extensions.

BroadcastTimeout : REG_DWORD : 1 (1-65535, half-seconds)

Specifies the time between sending find-name requests. This value is not affected if Internet is set to 1. (Related parameter: BroadcastCount.)

BroadcastCount : REG_DWORD : 3 (1-65535, times)

Specifies the number of times to send a broadcast. This value is not affected if Internet is set to 1. (Related parameter: BroadcastTimeout.)

ConnectionCount : REG_DWORD : 5 (1-65535, times)

Specifies the number of times to send a connection probe. A connection probe is sent by the initiator of a session if a connection could not be made to the remote computer. (Related parameter: ConnectionTimeout.)

ConnectionTimeout : REG_DWORD : 2 (1-65535, half-seconds)

Specifies the time between sending connection probes when initiating a session.

InitialRetransmissionTime : REG_DWORD : 500 (1-65535, milliseconds)

Specifies the initial value for the retransmission time. (Related parameter: RetransmitMax.)

Internet : REG_DWORD : 1 (0 - False or 1 - True)

Specifies whether to change the packet type from 0x04 to 0x14 (Novell WAN broadcast).

KeepAliveCount : REG_DWORD : 8 (1-65535, times)

Specifies the number of times to send a session-alive frame before timing out if there is no response. (Related parameter: KeepAliveTimeout.)

KeepAliveTimeout : REG_DWORD : 60 (1-65535, half-seconds)

Specifies the time between sending session-alive frames. (Related parameter: KeepAliveCount.)

RetransmitMax : REG_DWORD : 8 (1-65535, times)

Specifies the maximum number of times the sender should retransmit before assuming that something is wrong with the link. (Related parameter: InitialRetransmissionTime.)

IPX/SPX Parameters (Network Interface Cards)

Registry path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services

               \NWLink\NetConfig\Driver01

These parameters are specific for each binding of NWLink to each network adapter. Currently, only one card is supported.

AdapterName : REG_DWORD : <Adapter name>

Specifies the name of the adapter NWLink will use. This parameter is set when you choose a network adapter to bind NWLink using the Network icon in Control Panel.

BindSap : REG_DWORD : 8137 (hex)

Specifies the Ethertype if the frame format is Ethernet II. The Ethertype field is only relevant if Ethernet II frames are to be sent or received. You can choose the frame type using the Network icon in Control Panel. For more information, see the PktType parameter.

EnableFuncaddr : REG_DWORD : 1 (0 - False or 1 - True)

When true, this parameter specifies that the IPX functional address is enabled if the adapter is a Token Ring card. If false, the IPX functional address is not added. The IPX functional address is C00000800000 (hex). Novell has been phasing out the use of this address, but it is still used in some places. It is up to the application to take advantage of the IPX functional address. In most instances, the broadcast address (FFFFFFFFFFFF hex) is used.

MaxPktSize : REG_DWORD : 0 (0-65535)

Specifies the maximum frame size the network adapter should be allowed to transmit. If this number is 0, NWLink will get this information from the adapter driver. This parameter allows the administrator to make the maximum transmit size smaller than the driver allows. A scenario in which you might want to change this entry is in an environment in which the network adapter on one side of a conversation is on a link that has a larger frame size than the link on the other side. For example, if the sending station is linked to a 16 MBPS Token Ring and the receiving station is linked to an Ethernet network.

NetworkNumber : REG_MULTI_SZ : 0 (network number in hex)

Specifies the network number to be used for this adapter. If it is 0, NWLink gets the network number from the network as it is running. This parameter is set using the Network icon in Control Panel. IPX network numbers are 4 bytes (8 hex characters) long. An example of an IPX network number is AABBDDFF. You should not have to enter a specific value because NWLink will determine it for you. Make sure to get the network number for your IPX subnet from the network administrator if you want to enter a specific number.

PktType : REG_DWORD : 1 (0-4)

NWLink supports Ethernet, Token Ring, FDDI, and Arcnet topologies. The PktType parameter specifies the packet form to use. The valid values are:

   0 (Ethernet II)
   1 (Ethernet 802.3)
   2 (802.2)
   3 (SNAP)
   4 (Arcnet)

If your adapter is an Ethernet adapter, choose between 0 and 3. If the adapter is Token Ring or FDDI, choose option 2 or 3. If you are using an Arcnet adapter, choose option 4. If the adapter is a Token Ring or FDDI adapter, values 0 and 1 will work the same as value 2. (Related parameter: BindSap.)

RipAgeTime : REG_DWORD : 5 (1-65535, minutes)

IPX maintains a routing information protocol (RIP) cache in order to locate machines on a remote network. The RipAgeTime entry informs IPX how many minutes to wait before requesting a RIP update for an entry. This timer is reset when a RIP announcement is received for an entry that is in the RIP cache.

RipUsageTime : REG_DWORD : 15 (1-65535, minutes)

IPX maintains a RIP cache in order to locate machines on a remote network. The RipUsageTime entry informs IPX how many minutes to wait before an entry in the RIP cache will be deleted from the cache. This timer is reset when a packet is sent to the remote machine.

SourceRouteBcast : REG_DWORD : 0 (0 or 1)

Specifies the source route to be used when transmitting a packet to the broadcast MAC address (FFFFFFFFFFF hex). If this value is 0, the packet is transmitted to the single-route broadcast (0xC2, 0x70). If the value is 1, the packet is transmitted to the all-routes broadcast (0x82, 0x70). (Related parameters: SourceRouteDef, SourceRouting, and SourceRouteMCast.)

SourceRouteDef : REG_DWORD : 0 (0 or 1)

Specifies the source route to be used when transmitting a package to a unique MAC address that is not in the source routing table. If the MAC address is in the source routing table, the route in the table will be used. If this value is 0, the packet is transmitted to the single- route broadcast (0xC2, 0x70). If the value is 1, the packet is transmitted to the all-routes broadcast (0x82, 0x70). (Related parameters: SourceRouteBcast, SourceRouting, and SourceRouteMCast.)

SourceRouting : REG_DWORD : 0 (0 - False or 1 - True)

Specifies whether to use source routing. This parameter is only used if the adapter is Token Ring. If there are no source routing bridges on the Token Ring, disable this entry to disable all of the source routing logic. (Related parameters: SourceRouteBcast, SourceRouteDef, and SourceRouteMCast.)

SourceRouteMcast : REG_DWORD : 0 (0 - False or 1 - True)

Specifies the source route to be used when transmitting a packet to a multi-cast MAC address (C000xxxxxxxx). If false, the packet is transmitted to the single-route broadcast (0xC2, 0x70). If true, the packet is transmitted to the all-routes broadcast (0x82, 0x70). (Related parameters: SourceRouteBcast, SourceRouteDef, and SourceRouting.)

IPX/SPX Parameters (Global)

Registry path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services

               \NWLink\Parameters

The following parameters are global for the entire NWLink transport.

ConnectionCount : REG_DWORD : 10 (1-65535, times)

Specifies the number of times the probe is sent when SPX is trying to connect to a remote node. If no response is received after the probes are sent, an error occurs. (Related parameter: ConnectionTimeout.)

ConnectionTimeout : REG_DWORD : 2 (1 to 65535, half-seconds)

Specifies the time between connection probes when SPX is trying to connect to a remote node. (Related parameter: ConnectionCount.)

KeepAliveTimeout : REG_DWORD : 12 (1-65535, half-seconds)

Specifies the amount of time the local side should wait before sending a probe to the remote side to verify that the SPX connection is still alive. (Related parameter: KeepAliveCount.)

KeepAliveCount : REG_DWORD : 8 (1-65535, times)

Specifies how many times to send a keep-alive probe before timing out if there is no response. (Related parameter: KeepAliveTimeout.)

RipCount : REG_DWORD : 5 (1-65535, times)

When the RIP protocol layer is trying to find a route on the network, this parameter specifies how many times to send a request before giving up. (Related parameter: RipTimeout.)

RipTimeout : REG_DWORD : 1 (1-65535, half-seconds)

Specifies the timeout between RIP request packets being sent out when the RIP protocol layer is trying to find a route on the network. (Related parameter: RipCount.)

WindowSize : REG_DWORD : 4 (1-10, SPX packets)

Specifies the window to use in the SPX packets. SPX uses the Allocation field of the SPX packet to tell the remote node how many receives are available for receiving data. The WindowSize entry specifies what value to put in the SPX Allocation field.

Additional reference words: prodnt
Keywords : NTINTEROP NTSrv kbinterop kbfasttip
Version : 3.1
Platform : winnt

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Last reviewed: January 14, 1998
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