DHCP discovery of WINS servers

Christopher R. Hertel crh at nts.umn.edu
Tue Sep 4 09:58:05 GMT 2001

> On Sun, 2 Sep 2001, Andrew Bartlett wrote:
> >I've been thinkg about this, and there are a few other issues:  
> > - we now have the start of wins fail-over support, so we now cope with
> >multiple wins servers (in HEAD, where I would apply such a patch).
> Yes, the patch will need to be modified a bit to create a list of wins
> servers to pass to handle_wins_server_list().

Andrew, have you had a chance to look at handle_wins_server_list() to see 
if we can change it from a string to a list format?

> > - we don't want to be doing a dhcp operation for *every* client
> >operation.  While its fine to do it each time the server starts, doing
> >it every time a client (like smbclient) starts could be a little
> >overkill.
> We don't. Only nmbd gets a list of wins servers to use when it starts up
> the first time. smbd and smbclient or any other program doesn't do any
> dhcp.

If so, then how does smbclient discover its WINS server?  Same for 
nmblookup?  These tools need to have a WINS server and (I think) they 
currently get their WINS server by reading smb.conf.

> > - what if our request is lost?  UDP is lossy, should we at least make
> >some attempt to send a second request?
> The more attempts we make, the longer nmbd will take to start doing its
> job: registering names and workgroups with the network and wins server. At
> least, with the way the dhcp stuff is implemented right now.  

Yes, but if we don't get an answer then we don't have a WINS server.  That
puts us in "B" mode.

I suppose we could use the list delimiters in loadparms to do something 
like this:

  wins server = dhcp | :

The idea is "try DHCP first, but if that fails use this list of IPs". 
(I'm not sure about the '|' delimiter but you get the idea.)  That further
suggests something like this:

  wins server = dhcp : :

which (noting the delimiter change) would retrieve the WINS list from 
dhcp and add the additional IPs to the end of the list.  List order is 
significant in WINS Failover.

> Does it make sense to add this minimal bit of functionality and expand it
> if people find it useful?

It sounds good to me.  This feature is available in DHCP so why not use it?

Chris -)------

Christopher R. Hertel -)-----                   University of Minnesota
crh at nts.umn.edu              Networking and Telecommunications Services

    Ideals are like stars; you will not succeed in touching them
    with your hands...you choose them as your guides, and following
    them you will reach your destiny.  --Carl Schultz

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