[Fwd: Re: Backup browser question.]

Christopher R. Hertel crh at ubiqx.mn.org
Sun Nov 3 20:22:00 GMT 2002

John H Terpstra wrote:
> On Sat, 2 Nov 2002, Christopher R. Hertel wrote:
> > The rule of thumb, as I've seen it stated in some olde Windows95
> > documentation, is that following the election of the Local Master
> > Browser, one of the other Potential Browsers is selected to be a
> > Backup Browser.  For every 32 nodes on the subnet (how is this
> > determined) there is supposed to be yet another Backup Browser.
> This is correct. Certainly up to NT3.51 Microsoft maintained that NT did
> the same as WfW networking in respect of Backup Master Browser /
> Potential master browser behaviour.
> > That's what the docs say anyway.  What I find annoying is that I cannot
> > get W/NT4 to select another node as a backup browser.  This suggests
> > that the "real" formula is
> >
> >   Backup Browser count = 0 + trunc( nodes / 32 )
> No matter what, you must have at least one BMB.

One backup... Yes, I thought about it a lot last night and I *think* that
the Backup Browser selects itself during the election by sending an election
packet with the Backup Browser bit set.

> PS: I recall in the WfW resource kit reading that WfW elects a BMB for
> every 15 nodes. NT3.1 changed this to 1 in 32 as I recall.

Makes sense.  They were probably afraid that being a Browser node would
put a strain on the system (we are talking 386's running Windows, after
all).  Once the 486's started coming out, and they had a bit more experience
with it, they probably upped the number.

> >
> > instead of
> >
> >   Backup Browser count = 1 + trunc( nodes / 32 )
> >
> > Thing is, I want to take a look at the protocol used to update the
> > Backup Browsers from the LMB's list.
> >
> > Any clues anyone?
> Don't know if my comments help.

They confirm my read of the documentation.  Thing is:

1) When I capture a browser lookup, I am seeing that the GetBackupList
   request, and the reply (both from Samba and from Windows) shows only
   one name in the Backup Browser list.  That name is the name of the
   Local Master Browser.

2) I don't know how the LMB goes about counting the nodes on the LAN.
   I suppose it's looking at the announce messages.

3) I don't know how the LMB goes about telling a node that it should be
   a Backup Browser.

These are things that I want to learn so that I can document them.
Once again, all clues are helpful.


Chris -)-----

Samba Team -- http://www.samba.org/     -)-----   Christopher R. Hertel
jCIFS Team -- http://jcifs.samba.org/   -)-----   ubiqx development, uninq.
ubiqx Team -- http://www.ubiqx.org/     -)-----   crh at ubiqx.mn.org
OnLineBook -- http://ubiqx.org/cifs/    -)-----   crh at ubiqx.org

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