Microsoft KB Archive/97599

= Windows NT RAS Registry Parameters =

Article ID: 97599

Article Last Modified on 10/31/2006

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APPLIES TO


 * Microsoft Windows NT Advanced Server 3.1
 * Microsoft Windows NT Workstation 3.1

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This article was previously published under Q97599



WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

Remote Access generally supplies good default values for the Remote Access Service (RAS) parameters. However, for some systems, you may want to adjust individual parameters to suit your particular performance and security needs.

This article provides a complete list of parameters that can be adjusted in the Registry Database (use Registration Information Editor), arranged in the following categories:


 * Remote Access Parameters
 * NetbiosGateway Parameters
 * AsyncMac Parameters
 * RasHub Parameters

Note: Every value listed in this article uses a REG_DWORD data type, except for NetworkAddress, which uses a REG_SZ data type.

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

For information on adding Registry values, see the online help provided for Registration Information Editor, or query on the following here in the the Microsoft Knowledge Base:

modify and ras and registry

REMOTE ACCESS PARAMETERS
Remote Access parameters are listed by parameter name and can be found in the following Registry subkey:   SYSTEM\CurrentControlSet\Services\RemoteAccess\Parameters Parameter               Range         Use --

AuthenticateRetries     0-10          Sets the maximum number of                         default = 2   unsuccessful retries at                                       authentication.

AuthenticateTime        20-600 secs. Sets the maximum amount of time default: 120 a user is allowed to finish authentication.

CallbackTime            2-12 secs. Sets the time interval the default: 2   server waits before calling the client back; client communicates the value of its own callback time when connecting to a Remote Access server. If the client does not communicate a callback time value (as with Remote Access                                      1.0 and 1.1 clients), the value of this parameter is used.

EnableAudit             0 = disabled  Enables or disables Remote 1 = enabled  Access auditing default: 1

NetbiosGatewayEnabled   0 = disabled  Makes the server function like 1 = enabled  a NetBIOS gateway, allowing default: 1   clients to access the LAN. If                                      disabled, remote clients can access the files on the server in a point-to-point connection only.

NumRecvQueryIndications 1-32          Allows Remote Access clients to                         default: 3    initiate simultaneous, multiple network connections.

NETBIOS GATEWAY PARAMETERS
In Windows NT 3.1, the NetBIOS Gateway parameters are listed by parameter name and can be found in the registry under the the HKEY_LOCAL_MACHINE subtree under the following subkey:  SYSTEM\CurrentControlSet\Services\RemoteAccess\Parameters\NetbiosGateway NOTE: In Windows NT 3.5 and 3.51, the Autodisconnect parameter is under the the HKEY_LOCAL_MACHINE subtree under the following subkey:   SYSTEM\CurrentControlSet\Services\RemoteAccess\Parameters For additional information, refer to the RemoteAccess Parameters section in the Windows NT Server 3.5 Remote Access Service manual on page 82. Parameter          Range             Use --

AutoDisconnect     0-60000 minutes. Sets the time interval after default: 20      which inactive connections are terminated. Inactivity is                                     measured by lack of session data transfer. You may want to set this parameter to 0 minutes if                                     clients are running NetBIOS datagram applications. Setting this parameter to 0 disables AutoDisconnect.

DisableMcastFwd    0 = disabled      Allows session traffic to have WhenSessionTraffic 1 = enabled       priority over multicast data- default: 1       grams. This means that multicast datagrams are transferred only when there is no session traffic.

EnableBroadcast    0 = disabled      Determines whether broadcast 1 = enabled      datagrams are forwarded to                    default: 0        remote workstations. See MulticastForwardRate.

MaxBcastDgBuffered 16-255            Sets the number of broadcast default: 32      datagrams that the gateway buffers for a client.

MaxDgBufferedPer   1-255             Sets the number of datagrams GroupName          default: 10       that can be buffered per group name. Because this setting is                                     done in virtual memory, you can set it high.

MaxDynMem          131072-           Sets the amount of virtual 4294967295     memory used to buffer NetBIOS default: 655350  session data for each remote client. (See Note 1, below.)

MaxNames           1-255             Sets the number of unique default: 255)    NetBIOS names that each client                                      can have. NetBIOS stacks on the                                      LAN have a maximum of 255 names                                      allocated for all clients                                      (cumulative). For example: To                                      allow 64 clients to connect                                      simultaneously, set this                                      parameter to 3 or 4.

MaxSessions        1-255             Sets the maximum number of                    default: 255      simultaneous NetBIOS sessions each client can have. NetBIOS stacks on the LAN have a maximum of 255 names allocated for all clients. (See Note 2, below.)

MultiCast          -1 to             Governs the multicasting of ForwardRate           4294967295      server announcements (group name                      secs            datagrams) to all remote work- default: 5       stations in a server's domain. -1 Disables forwarding. 0 Guarantees delivery of group name datagrams. n Forwards datagrams every n                                          seconds. (See Note 3, below.)

RcvDgSubmitted     1-32              Determines how many NetBIOS PerGroupName       default: 3        Receive Datagram commands can be                                      submitted simultaneously for each group name on the LAN stack. Keep this setting as small as possible to minimize the amount of memory consumed by system resources. Each datagram command received locks about 1.5K of physical memory in                                     the system.

RemoteListen       0-2               Sets the remote NCB_LISTEN capa- default: 1       bility. (Microsoft recommends                                     using the default value.) 0 Client can't post NCB_LISTEN for any NetBIOS name. 1 Remote client can receive messages from LAN users and printers. Client can post NCB_LISTEN on Windows NT                                         Advanced Server aliases only. 2 Enables NCB_LISTEN for all remote client NetBIOS names, enabling them to run NetBIOS server applications and to                                         act as servers on the network. (See Note 4, below.)

SizWorkBufs        1024-65536         Sets the size of work buffers. default: 4500     The default setting is optimized for the server message block (SMB) protocol, the protocol between the workstation and the server running on Windows NT Advanced Server. NOTES:


 * 1) Because the Remote Access server is a gateway between the slow line and the LAN, data is buffered in its memory when coming from the fast line (LAN) to the slow (asynchronous) line. The Remote Access server minimizes the usage of physical memory by locking only a minimal set of pages (about 64K per client) and making use of virtual memory to buffer the rest of the data. As long as you have enough disk space on your backup store, you can increase this parameter if needed.

If you have an application with a LAN (fast) sender and an async (slow) receiver, and if the sender is sending more data at a time than the Remote Access server can buffer, the Remote Access server tries to apply a form of NetBIOS level flow control by not submitting NCB_RECEIVE on the session, until it has enough buffer space to store incoming data. In this situation, you should increase your NetBIOS SEND and RECEIVE time-outs so that the fast sender can keep pace with the slow receiver.
 * 1) For a gateway, you should set the size of Nbf to 3 (large). This removes any limit on how much memory NetBEUI allows itself to use. A size of 2 means a limit of 300K, which is enough for about 64 normalconnections. The Registry subkey for this parameter is SYSTEM\CurrentControlSet\Services\Nbf\Parameters.
 * 2) If there are many servers in the domain, the flow of announcements may appear as a continuous stream of datagrams directed to remote workstations. Because these announcements are repeated, they waste CPU cycles at workstations without any real information gain in return.The MultiCastForwardRate parameter makes it possible to filter server announcements by forwarding them at a specified interval.

If the EnableBroadcast parameter is set to 0, then broadcasts are not forwarded, even if the MultiCastForwardRate parameter is set to a positive number (in this case, only multicast datagrams are forwarded). If MultiCastForwardRate is set to -1, then broadcasts are still not forwarded even if EnableBroadcast is set to 1. (See the EnableBroadcast parameter.)
 * 1) The NCB_LISTEN capability can significantly drain system resources. If the RemoteListen parameter is configured to 2, Remote Access posts an NCB_LISTEN on all NetBIOS names of Remote Access clients. Considering that the average Windows NT Advanced Server workstation has about 5 NetBIOS names assigned to it, the total number of NetBIOS names for which an NCB_LISTEN would be posted is 5 times 64 (the maximum number of clients per Remote Access server).

ASYNC MAC PARAMETERS
Asynchronous Media Access Control (MAC) parameters are listed by parameter name and can be found in the following Registry subkey: SYSTEM\CurrentControlSet\Services\AsyncMacn\Parameters Parameter          Range            Use --

FramesPerPort      2-20             Allocates frames for each dial-in default: 3      or dial-out port. Set this value to the number of frames the transport may have outstanding at                                    any given time.

IrpStackSize       1-10             Sets the number of device drivers default: 5      MAC is layered above. Increase this value only if the serial driver below the MAC needs more stack size.

MaxFrameSize       576-1514         Determines the maximum frame size default: 1514   Use smaller frames for noisy links.

RAS HUB PARAMETERS
RAS Hub parameters are listed by parameter name and can be found in the following Registry subkey:   SYSTEM\CurrentControlSet\Services\RasHub\Parameters Parameter          Range           Use --

NetworkAddress     -           Reassigns the first 4 bytes of the 6-byte IEEE address. For example, if you reset the address to                                   &quot;03-1F-2C-81-92-34,&quot; only the first 4 bytes are looked at. Reset this parameter in the RasHub\Parameters subkey with the REG_SZ data type.

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Keywords: kbnetwork KB97599

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