Windows NT Browser v40doc.docx

Windows NT Browser v40doc.docx

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WindowsNTBrowserv40doc

®

WindowsNT®Server

ServerOperatingSystem

MicrosoftWindowsNTBrowser

WhitePaper

ByR.DanThompsonIVandRandyMcLaughlin

Abstract

ThiswhitepaperprovidesinformationandproceduresforimplementingtheMicrosoftWindows NTBrowseronMicrosoftWindows NT®4.0operatingsystem–basedclientworkstationsandservers.

©1999MicrosoftCorporation.Allrightsreserved.

TheinformationcontainedinthisdocumentrepresentsthecurrentviewofMicrosoftCorporationontheissuesdiscussedasofthedateofpublication.BecauseMicrosoftmustrespondtochangingmarketconditions,itshouldnotbeinterpretedtobeacommitmentonthepartofMicrosoft,andMicrosoftcannotguaranteetheaccuracyofanyinformationpresentedafterthedateofpublication.

ThisWhitePaperisforinformationalpurposesonly.MICROSOFTMAKESNOWARRANTIES,EXPRESSORIMPLIED,INTHISDOCUMENT.

TheBackOfficelogo,Microsoft,Windows,andWindowsNTareregisteredtrademarksofMicrosoftCorporation.

Otherproductorcompanynamesmentionedhereinmaybethetrademarksoftheirrespectiveowners.

MicrosoftCorporation•OneMicrosoftWay•Redmond,WA98052-6399•USA

0599

Contents

Introduction1

MSBrowsingOverview2

MicrosoftNetworkBrowserSystem2

HowServersManageBrowsingforMicrosoftNetworking2

MultiprotocolConsiderations3

MasterBrowserElections3

RoleofMasterBrowsers5

RoleofBackupBrowsers5

RoleofDomainMasterBrowsers5

BrowserFailureswithMicrosoftNetworking6

HowServersAnnounceThemselvesinMicrosoftNetworks7

NetBIOSSpecialNames7

SamplesofNetBIOSSpecialNames8

HowClientsReceiveBrowserInformation10

MicrosoftTCP/IPandNameResolution12

NetBIOSoverTCP/IP12

ComputerNameandHostNameResolutionwithNetBIOSoverTCP/IP13

WANBrowsingwithWINSonanIPNetwork15

TroubleshootingBrowsing17

ForMoreInformation21

AppendixA:

BrowsinginaSwitchedEnvironment22

AppendixB:

TheMultihomedWindowsNTBrowser23

AppendixC:

WindowsNTPrinterBrowsing24

AppendixD:

WindowsNTBrowserComponents26

AppendixE:

WindowsNTBrowserRegistryOptions28

AppendixF:

windows NTBrowserErrorCodes31

AppendixG:

NetworkLayersInvolvedinBrowsing36

MACLayer36

NetworkLayer36

NetBIOSLayer36

SMBLayer36

AppendixH:

WindowsNTBrowserProtocolFrames38

ServerTypeField38

HostAnnouncementFrame38

LocalMasterAnnouncementFrame40

Domain/WorkGroupAnnouncementFrame41

AnnouncementRequestFrame42

ElectionFrame42

BecomeBackupFrame43

GetBackupListRequestFrame43

GetBackupListResponseFrame44

MasterAnnouncementFrame44

ResetBrowserStateFrame44

Introduction

MaintaininganaccurateandefficientbrowselistonthenetworkisimportanttopicforMicrosoftcustomers.Thistechnicalpaperprovidesup-to-dateinformationonMicrosoftnetworkbrowserarchitectureandreferencematerialforadvancedtroubleshootingofbrowsingissues.

Thebrowselistcanbeaccuratelymaintainedinanyenvironmentifthebrowserarchitecture,capabilities,andthewayinwhichthenetworktopologyaffectsthebrowser’sabilitytogatherinformationonthenetworkaretakenintoconsideration.

UnderstandingtheoperationofthebrowserservicesavailableonMicrosoftoperatingsystemsiscriticalineffectivetroubleshooting.Forexample,thebrowserservicereliesonbroadcastswhengatheringinformationlocallyandneedstheservicesofWINSorothername-resolutionmethodstopassabrowselisttoremotenetworks.Thedetailsofthisprocessandthemethodsusedarepresentedinthispaper.

Thispapershoulddispelsomecommonmisunderstandingsaboutthebrowselist.Thepresenceorlackofacomputernameinthebrowselistdoesnotgiveaclearindicationofthecomputer’sstatusonthenetwork.Adelayingatheringabrowselistmayoccurduetovariouscircumstances;however,asystemcantypicallybecontacteddirectlyeventhoughitcannotbefoundinNetworkNeighborhood.Asystemmissingfromthebrowselistshouldnotbeacauseforimmediateconcern,unlessthesystemisconsistentlymissing.

Althoughtheprimaryfocusofthispaperistogivenetworkadministratorsanunderstandingofbrowserarchitecture,italsodealswithtroubleshootingsituationswherethebrowselistisinaccurateorunavailable.

MSBrowsingOverview

MicrosoftNetworkBrowserSystem

ThebrowserisanetworkresourceenumerationtoolfirstcreatedforLANManager1.0.WindowsforWorkgroupsenhancedthebrowsertomakeittrulyclient/server,andfinallyitwasenhancedfordomainbrowsingonaWindows NT®operatingsystem–basednetwork.TheMicrosoftnetworkingbrowsermaintainsalistcalledthebrowselist.Thebrowselistisanenumerationofalltheavailableservers,workgroups,anddomains（forWindows NTandLANManagernetworks）.Forexample,whenauserattemptstoconnecttoanynetworkresource,usingNetworkNeighborhood,thelistofserversthatappearsisthebrowselist.Thebrowselistisprovidedbyabrowserinthelocalcomputer’sworkgroupordomain.

TheMicrosoftnetworkingbrowsersystemconsistsofadomainmasterbrowser,masterbrowsers,backupbrowsers,andclientcomputers.Thedomainmasterbrowsermaintainsthecompletedomainbrowselist.Themasterbrowsersperiodicallyquerythedomainmasterbrowsertoobtainacompletelistofdomainresources.Themasterbrowsermaintainsthebrowselistandperiodicallysendscopiestothebackupbrowsers.Whenabrowserclientneedsinformation,itobtainsthecurrentbrowselistbysendingaNetServerEnum2calltoeitherthemasterbrowserorabackupbrowser.

NetServerEnum2returnsinformationabouttheservertype（SV_TYPE_SERVER）entriesinadomainorworkgroup.Itallowsclientcomputerstoviewaspecificsetofserversintheworkgroupordomain.NetServerEnum2providesaservertypemaskthatallowsuserstoqueryforvarioustypesofservers,suchasworkstations,servers,timeservers,domaincontrollers,andsoon.PrinterbrowsingandWindowsTerminalServerclientsrelyonthistypeofbrowsingtoenumeratetheirrespectiveresources

ThiscentralizedbrowserarchitectureforWindowsnetworkingresourcesreducesthenumberofbroadcastdatagramsonthenetwork.Adatagramisanetworkpacketthatissenttoamailslotonaspecifiedcomputer（a directeddatagram）ortoamailslotonanynumberofcomputers（a broadcastdatagram）.Thecentralizedbrowserarchitecturealsoreducesthedemandsontheclientcomputer’sCPUandmemory.

Note:

ForMicrosoftnetworkingusingtheMicrosoftTCP/IPprotocol,broadcastnameresolutionisadirectimplementationofRequestforComments（RFCs）1001and1002（NetBIOSServiceProtocols）.ThisimplementationofNetBIOSoverTCP/IPiswhollycompliantwiththeRFCs,anddoesnotinvolveanymethodofwhathasbeenreferredtoasNetBEUIencapsulation.FormoreinformationaboutNetBIOSoverTCP/IP（NetBT）,seethediscussionofnameresolutionforWindows-basednetworkinginWindows NTServerNetworkingGuide.

HowServersManageBrowsingforMicrosoftNetworking

InaWindows NTdomain,everyWindows NTServer–basedcomputerisabrowser.Theprimarydomaincontroller（PDC）,ifthereisone,isthedomainmasterbrowser,andtheothercomputersrunningWindows NTServer,Windows NTWorkstation,ortheWindows® 95operatingsystemarebackupbrowsers.IfthereismorethanoneWindows NTServer–basedcomputerinthedomain,nocomputerrunningWindows NTWorkstationorWindows 95shouldeverbeamasterbrowserinthedomain.InaworkgroupcontainingcomputersrunningWindows95andWindows NTWorkstation,thereisalwaysonemasterbrowser.IfthereareatleasttwoWindows 95-orWindows NTWorkstation–basedcomputersintheworkgroup,thereisalsoonebackupbrowser.Forevery32computersrunningWindows 95andWindows NTWorkstationintheworkgroup,thereisanotherbackupbrowser.Thefollowingsectiondescribeshowcomputersbecomebrowsersandsummarizestherolesplayedbymasterandbackupbrowsers.

MultiprotocolConsiderations

Thebrowsermaintainsallofitsserverinformationonaper-transportbasis.Atransportisthephysicalnetworkcardboundtoaprotocol.WhenaclientapplicationissuesaNetServerEnumcall,thecoderunningontheworkstationenumeratesalltheservicednetworksandforwardstheNetServerEnumcalltoabrowserserverforthatparticulartransport.Whenabrowserserverreceivestherequest,itreturnsonlythoseserversonthesamenetworkfromwhichitreceivedthetransactionoriginally.Therefore,browsingoccursoneachtransportindependently,regardlessofotheravailabletransports.

MasterBrowserElections

EachcomputerrunningWindows95,WindowsforWorkgroups,Windows NTWorkstation,orWindows NTServerhasconfigurationsettingsthatdeterminewhetherthatcomputercanbecomeabrowser.ForserversrunningWindowsNT,thevalueforMaintainServerListforthebrowserservicedeterminesitspossibleroleasabrowser.Bydefault,serversareconfiguredtohavethepotentialtobecomebrowsers.Unlesstheserverisspecificallyconfiguredtoneverbeabrowser,theMicrosoftnetworkingbrowserservicestartsautomaticallywhenthecomputerstarts,andtheserverannouncesitselfonthenetworkingusingthespecialNetBIOSname<1e>.

Amasterbrowserelectionalwaysoccursinthefollowingcircumstances:

∙Whenacomputercannotfinditsmasterbrowseratsystemstartup

∙Whenacomputerdeterminesthatamasterbrowserhasdisappeared

∙WhenacomputerrunningWindows NTServerstarts（thatis,apreferredmasterbrowserisstarted）

Whenanyserverneedstoforceamasterbrowserelection,itnotifiestheotherbrowsersonthesystembybroadcastinganelectiondatagramthatcontainsthesendingbrows