RE: GMC Network - (Long)

[Jorge Gomes Silva <jgs plurimarketing pt>]

[OFF TOPIC]

Probably this is not the right place for this topic but since it started 
here and since it may be interesting to help understand Windows networks 
I'm posting this here.

=> Network Browsing in TCP/IP Windows Networks <=

There are 3 important roles when it comes to browsing a Windows Network:

"Domain Master Browser"
"Master Browser"
"Backup Browser"

The following is a transcript (I removed some parts of the text and 
included what I think it is the essential) from technet with my comments 
between []:

*** Domain Master Browser ***

The domain master browser is responsible for collecting announcements for 
the entire domain, including any network segments, and for providing a list 
of domain resources to master browsers. The domain master browser is always 
the primary domain controller (PDC) of a domain.
For a domain that uses TCP/IP and spans more than one subnetwork, each 
subnetwork functions as an independent browsing entity with its own master 
browser and backup browsers.
When a domain spans multiple subnetworks, the master browser of each 
subnetwork announces itself as the master browser to the domain master 
browser, using a directed [note: "directed"] MasterBrowserAnnouncement 
datagram. The domain master browser then sends a remote NetServerEnum API 
call to each master browser, to collect each subnetwork's list of servers. 
The domain master browser merges the server list from each subnetwork 
master browser with its own server list, forming the browse list for the 
domain. This process is repeated every 15 minutes to ensure that the domain 
master browser has a complete browse list of all the servers in the domain.
The master browser on each subnetwork also sends a remote NetServerEnum API 
call to the domain master browser to obtain the complete browse list for 
the domain. This browse list is available to browser clients on the 
subnetwork.
*** Master Browser ***
The master browser is responsible for collecting the information necessary 
to create and maintain the browse list. The browse list includes all 
servers in the master browser's domain or workgroup, and the list of all 
domains on the network.
Individual servers announce their presence to the master browser by sending 
a directed [note: "directed"] datagram called a server announcement to the 
domain or workgroup master browser. Computers running Windows NT Server, 
Windows NT Workstation, Windows for Workgroups, Windows 95, or LAN Manager 
send server announcements. When the master browser receives a server 
announcement from a computer, it adds that computer to the browse list.
*** Backup Browser ***
The backup browser receives a copy of the network-resource browse list from 
the master browser and distributes the list upon request to computers in 
the domain or workgroup [i.e. when some Windows user clicks the "Network 
Neighborhood icon"].
Backup browsers call the master browser every 15 minutes to get the latest 
copy of the browse list and a list of domains. Each backup browser caches 
these lists and returns the list of servers to any clients that send a 
remote NetServerEnum API call to the backup browser. [i.e. when some 
Windows user clicks the "Network Neighborhood icon"]
End of transcript.

I won't go into browser election.

How do clients know which computers are the browsers ? WINS. How does it 
work ? Browsers register specific names in the WINS Server where the last 
(16th) character (byte) of name has a special meaning. Two examples:

<Domain Name><1B> - "Domain master browser name.  This name identifies the 
primary domain controller and indicates which clients and other browsers to 
use to contact the domain master browser. " (from technet);

<Domain Name><1D> - "The master browser name that is used by clients to 
access the master browser. There is one master browser on a subnet." (from 
technet) [this is a list of addresses. Not only one address];

When a client wants to get the computers in the network neighborhood it 
asks WINS for the master browser address, it gets a list of Backup Browsers 
from the master browser and it retrieves a list of servers from a select 
Backup Server.

Conclusion: A client doesn't need to issue broadcasts to get the "Network 
Neighborhood". However depending on the type of node a Windows machine is 
configured as (node type is another concept. It defines in which way a 
computer will resolve a name to an IP address) it may be using broadcast to 
resolve names to IP and only after that it will use WINS. In that case you 
have broadcast but it's not necessary.

So, does this idea of WINS and browsers work well ? When you consider very 
large networks the answer is NO. In large networks the replication of WINS 
databases among WINS servers is a big pain. WINS management is horrible and 
very unflexible.

Sorry for the long mail. Don't flame me please.

Jorge.

On Terca-feira, 29 de Dezembro de 1998 13:24, Bobo Rajec 
[SMTP:bobo@bspc.sk] wrote:
> [OFFTOPIC]
>
> Thus spake Jorge Gomes Silva:
>
> > Brandon S. Allbery [SMTP:allbery@hilfy.ece.cmu.edu] wrote:
> > > that a bunch of Windows boxes spamming the network every 30 seconds 
isn't
> > > noticed.
> > You are wrong. That is true if you are running your Windows network 
over
> > NetBEUI. However if the network runs over TCP/IP (and this is what 
"large
> > companies" usually have) you can use WINS.
>
> He is right, unfortunately. You seem to be confusing announcement
> broadcasts, aka browsing broadcasts, and name resolution traffic,
> which could be either broadcasts or unicasts to the WINS server.
>
> What you see in the Network Neighbourhood (NN) window is the result of
> the browsing broadcasts. All windows machines produce these, unless
> you specifically disabled it ("browser service") on the NT servers and
> on all Windows machines.
>
> I do not want to go into details like browser selections, master
> browser, domain master browser and so on, it's all really crap.
>
> You use WINS server when you want to connect to the specified NetBIOS
> name. You could obtain this name from the NN window or you could type
> it in manually (net use x: \\server\share). This is the case when the
> windows machine asks the WINS server about the IP address of the
> specified NetBIOS name.
>
> That's why it happens so often that you see machines in the NN window
> that really aren't on the network anymore ("Specified name could not
> be found"), or you don't see nodes there when you are positively sure
> they are there, up and running.
>
> BTW: I've been on a large network with many servers and many pcs
> coming up and down all day long where the browsing traffic accounted
> for more than 60% of the broadcasts. It's *highly* recommended to
> disable the service and leave it running on at most 5-10
> machines. (bug: you cannot disable it in Wfw 3.11. Life is hard)
>
> 	bobo rajec
>
>
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