It must be mentioned, that UDP broadcast packets are not forwarded by routers. There can be a propagation delay of up to 15 minutes - the time interval between (or propagation delay) the various types of machine announcements that are sent over the UDP protocol. This works quite well over a local network.
At this point there is already a TCP/IP connection from which connections can be made to the shares and services that are available to the user. As it does the Windows client obtains its IP address and can proceed to open a connection to that address, after which it can request the list of resources that are available on that machine. When someone clicks on a machine in the browse list, the Windows client sends out a broadcast UDP packet seeking the owner of that machine name to respond. The client now has a list of machines that will initiate the browsing operation for the workgroup or domain. The Windows client then asks the master-browser to provide the list of machines it knows about (has in its cache). The master-browser will answer the request, thus informing the inquiring client of its IP address. The Windows client that seeks to browse a network environment will send a broadcast message over UDP to the local network segment seeking to find the master-browser. The master-browser collates the information that is propagated by each the NetBIOS nodes (Windows clients) so that it can be queried by local machines. As the size of the network grows, the impact of UDP broadcasts soon takes its toll on overall network performance.īrowsing of MS Windows networks is possible via two mechanisms:Ī) Resolution of NetBIOS names to IP addressesī) A machine on each network segment acting as a master-browser Broadcast-based name resolution works adequately on networks with few Windows clients. When NetBIOS is run over TCP/IP NetBIOS names can be resolved using UDP broadcasts. WINS is the Windows Internetworking Name Service. WINS is like a Dynamic- DNS service for NetBIOS networking names. WINS provides a mechanism for resolution of a NetBIOS name to its IP address.
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