On 13 Jan 2002, at 8:42, Nostradamus Systems wrote:

> > From:    [log in to unmask]
> >
> > 1.  You generally shouldn't have to change DNS server addresses.  Is
> > there some reason you think you need to?
>
> No - only that I thought it was necessary when splitting the "leased
> network" in two.

  No, as long as the PCs can *reach* them, it generally shouldn't
matter by what route.

> > 2.  Putting the alternative connections on the other side of a router
> > from the workstations, with NAT done at the router, should mean you
> > never have to change a workstation IP address.
> >
> > 3.  In a case where the actual gateway changes, rather than update
> > the gateway setting on each workstation, I point them all at a router
> > which may not really be a gateway itself at all, but "knows" -- via
> > OSPF or some other means -- about what gateways should currently be
> > used.
>
> What is OSPF please?

  OSPF is one of several "routing protocols" -- protocols by which
routers excahnge information about how the network is connected.  One
of the advantages of OSPF over some of the others is that it's good
at rapidly adapting to links going up or coming down -- i.e., to
tracking a network with dynamic connectivity.

> Is it feasible to:-
> Set the ISDN routers within the address range 10.0.0.xxx
> Add them to the list of Gateways on each PC.
> Mix  addresses 158.152.xxx.xxx (leased line router) and 10.0.0.x (ISDN)
> within the DNS - Server search Order.
>
> If the leased line  goes down then would the switch to ISDN be automatic,
> or would  a reboot be necessary to establish a working connection?

  No.  The routing information on each PC reflects a static view of
what links are available, with no provision for tracking which are up
and which are down.
  (NT supports RIP and 2000/XP support OSPF, but I think you'll be
best served by separating the dynamic network connectivity from the
individual PCs.)

David Gillett

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