Browsing Across Subnets

One of the causes of browser problems, and the constant complaint "I can't always see all of my computers in My Network Places!", is a backup browser server becoming separated from the master browser. As I stated in my main Browser article, The NT Browser...

Anytime that a backup browser realises that there is no master browser present on the domain, the browser is authorised to hold an election to determine a new master browser.

This behaviour is for 2 reasons.

  1. There must be a master browser available at all times, for browsing to work.
  2. There must be a master browser available on each subnet, for browsing to work.

Why is this relevant? It's because browser relationships, in general, do not pass from subnet to subnet. Browser communications, from a server to a backup or master browser, are by broadcasted datagrams. Broadcasted datagrams are sent to all computers on a subnet, but nowhere else. Routers drop broadcasted datagrams, so server advertisements, which are what the master browser depends upon to know that a server exists, stay on each subnet.

The master browser on the subnet assembles all of the server advertisements into the browse list for the subnet. If a domain is segmented, by either multiple subnets or just having multiple master browsers, it is the job of the domain master browser to collect the browse list from each segment master browser, aggregate the lists, and pass the aggregated list back to each segment master browser.

Here is one instance where a workgroup will not perform as well as a domain. If a workgroup is segmented, there will be no domain (workgroup) master browser, and no ability for servers on one segment to be seen from another segment. Segmented workgroups simply can't be browsed across segment boundaries.

Do you maybe have two (or more) routers, but would prefer to have one subnet? If so, then read about File Sharing On A LAN With Two Routers.