DOCUMENT:Q142692 06-AUG-2002 [winnt] TITLE :Minimizing WAN Traffic PRODUCT :Microsoft Windows NT PROD/VER::3.51 SP5,4.0 OPER/SYS: KEYWORDS:kbnetwork ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Server versions 3.51 SP5, 4.0 ------------------------------------------------------------------------------- IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base: Q256986 Description of the Microsoft Windows Registry SUMMARY ======= This article lists the modifications that have to be made to your computers deployed in a WAN environment, if you want to minimize the traffic over the routers. This information applies only to Windows NT 4.0 and Windows NT 3.51 Service Pack 5. This information can become very useful if, for example, you are using ISDN lines rather than leased lines. When using ISDN, each frame sent across the ISDN line may establish a new connection and, therefore, costs money. Thus, the operating cost of your ISDN lines can become very high. Because much of the traffic is generated by Windows NT domain controllers, this traffic can be dramatically reduced using these modifications. CAUTION: The parameter change included in this article has not been extensively tested in large installations. Microsoft cannot guarantee that modification of registry settings as recommended herein will accomplish the objective described in this article under all circumstances and in all configurations. MORE INFORMATION ================ WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk. Assume that your Windows NT systems have been spread across several sites interconnected by routers, and consider two typical cases: - A single domain split into several LANs, with one backup domain controller (BDC) on each LAN. - Several domains with trust relationships. This article includes a short description of the network frames that can Be encountered in the absence of the modifications described later in the article. The network traces were captured in a lab with the following configuration: - Name of domain = DOMWAN - Name of primary domain controller (PDC) = PDCWAN = 191.75.0.2 (on a separate LAN) - Name of backup domain controller (BDC) = BDCWAN = 191.76.0.2 (on a separate LAN) ----- | | ----- | PDC |-----| |----| BDC | 191.76.0.2 | WAN | | | | WAN | ----- | ISDN | ----- 191.75.0.2 |--- router <====> router ---| | 191.75.0.1 191.76.0.1 | The License Service May Generate Traffic Every 15 Minutes --------------------------------------------------------- The License service performs licensing replication. Data moves from BDCs and member servers to the PDCs, and then, optionally, from the PDCs to an enterprise server, which maintains licensing information across the whole network. This replication, by default, is performed one time every 24 hours. If, for some reason, the BDC cannot connect to the license service on the PDC, the BDC will continue to attempt replication one time every 15 minutes until it is successful. Reducing Exchange of Browse Lists --------------------------------- Every MasterPeriodicity time interval (every 12 minutes, by default), the master browsers, which are the BDCs, try to contact the domain master browser, the PDC, to exchange their browse lists. This parameter can be changed in the registry of all the BDCs: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Browser\Parameters Value : MasterPeriodicity DWORD Default : 720 To optimize the traffic on your WAN lines, increase the value above on all BDCs. SAM Replication Between a PDC and Its BDCs ------------------------------------------ The SAM replication is controlled by Netlogon on the PDC. The following registry value defines the typical pulse frequency (in seconds): HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetLogon\Parameters Value : Pulse REG_DWORD 60 to 172800 seconds (48 hours) Default : 300 For additional information, click the article number below to view the article in the Microsoft Knowledge Base: Q150350 NetLogon Maximum Value of Pulse Should Exceed 3600 All SAM/LSA changes made within this time are bundled together. After this period has elapsed, a pulse is sent to each BDC needing the changes. No pulse is sent to a BDC that is up-to-date. Increasing this value on the PDC reduces the number of replications between the PDC and the BDCs. Nevertheless, the SAM changes are propagated less quickly from the PDC to the BDCs. You must choose a balance between infrequent replication that may increase the number of connections to a PDC to validate changed passwords and frequent replication that may generate excessive ISDN traffic. The Netlogon PulseMaximum parameter has to be changed: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetLogon\Parameters Value : PulseMaximum REG_DWORD 60 to 172800 seconds (48 hours) It defines the maximum pulse frequency (in seconds). Every BDC will be sent at least one pulse at this frequency, whether its database is current or not. NOTE: The replication takes place immediately if a change is made in LSA secrets, for example, when adding a workstation to the domain or changing trusts relationships. Close of SMB Connections ------------------------ The following value specifies the maximum amount of time that a connection can be left dormant: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters Value : KeepConn REG_DWORD 1 to 65535 seconds Default : 600 (10 minutes) In a WAN environment, it is preferable to lower this value to 10 seconds on all the servers and the workstations, so that a new ISDN connection is not established just because of a SMB connection close. Changing KeepConn may generate significant SMB overhead. As connections are closed very quickly, each new connection implies the establishment of a new SMB connection. NetBIOS Name Resolution Mode ---------------------------- When you use a domain spanning into multiple sites, the NetBIOS name resolution mode should be set to m-node (broadcasts followed by name server) on all servers and workstations. This setting ensures that a local (for example, on the same subnet) domain controller is always contacted first (for example, before trying to contact the PDC). On Windows NT systems, the NetBIOS name resolution mode can be set to m-node with the modification of the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetBt\Parameters Value : NodeType REG_DWORD 4 (4 is for M-NODE) Trusts Relationships -------------------- Under certain circumstances, it is possible for 2 PDCs of 2 domains with a trust relationship to generate traffic every 15 minutes. For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base: Q152719 WAN and Trust: Traffic on the Wire Q154355 How to Tune Trusts for Dialup Routers in a WAN The following parameter defines the time interval during which Netlogon does miscellaneous work (on the PDC and on the BDCs), for example, finding a domain controller. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetLogon\Parameters Value : ScavengeInterval REG_DWORD 60 to 172800 seconds (48 hours) Default : 900 (15 minutes) Other Services That Generate Traffic ------------------------------------ Check out the configuration of your WINS database renewal interval, and the replicator service as well. The replicator service may be modified as follows: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Replicator\Parameters Value : Interval REG_DWORD 60 (minutes) Default : 5 (minutes) HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Replicator\Parameters Value : Pulse REG_DWORD 6 (6 * 60 minutes = 6 hours) Default : 3 For additional information about how to modify WINS settings, click the article numbers below to view the articles in the Microsoft Knowledge Base: Q142305 Min. and Max. Interval Values for WINS Configuration Q135922 Windows NT Registry Parameters for WINS Additional query words: ====================================================================== Keywords : kbnetwork Technology : kbWinNTsearch kbWinNT351search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbWinNTS351search kbWinNTS351sp5 Version : :3.51 SP5,4.0 Issue type : kbinfo ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.