Re: newbie to home network dhcp worries

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From: Herb Martin (news_at_LearnQuick.com)
Date: 01/09/05 

Date: Sun, 9 Jan 2005 16:32:11 -0600

"Leythos" <void@nowhere.lan> wrote in message
news:MPG.1c4b6f43f736567989e72@news-server.columbus.rr.com...
> In article <#YZzZCm9EHA.3640@tk2msftngp13.phx.gbl>, news@LearnQuick.com
> says...
> >
> > "Moon" <elmoono@yahoo.co.uk> wrote in message
> > news:undf21l9EHA.3504@TK2MSFTNGP12.phx.gbl...
> >
> > > > As long as the private side of both ADSL and BEFSR are different
> > > > networks you are fine.
> >
> > No, this is not fine unless the routing has been arranged.
> > (on the Modem), see below...
>
> Yes, it is, and it works fine. I can daisy change 100 linksys routers
> using DHCP on the WAN for IP and providing DHCP on the LAN side, and as
> long as each LAN side is a different subnet, the computers on the 100'th
> router will be fully able to reach the internet.

It will not work for the extra net -- it has nothing
to do with the daisy chain-- it has nothing directly
to do with the DHCP.

The problem is that the FIRST Modem/router cannot
find the interior subnet(s) UNLESS it has the IP of
the next most interior router.

IF it assigns that address dynamically it is not going
to know the address for you to give it a static route.

So, you must either give it a reservation -- which is
functionally equivalent to a manual address (note,
I said DHCP is NOT the real problem but rather the
dynamic address) OR you run a dynamic routing
protocol on BOTH(All) routers which is overkill
for such networks even if they all support such.

> > > Thanks, i now see why its working, but i will try some of the
suggestions
> > > like running nat just on the router.
> >
> > NO, you MUST run NAT on at least the Modem(the
> > most external device) and do not need it on the internal
> > router.
>
> NO, you don't have to run NAT on the modem, and you probably don't want

Look you need to think it through: THe EXTERNAL
router is going to get the ONLY public address, so
NAT there is ESSENTIAL and unavoidable.

ISP (public addresses) Mobem (privateAddresses) Router (private...)

NAT on any interior router is irrelevant and at best
unnecessary trouble.

> ISP <> MODEM - PUBLIC IP - LINKSYS ROUTER/NAT Private IP's (works good)

Exactly and that is why the MOST EXTERNAL router
must be the NAT -- that is LEFT MOST in your
configuration here.

> ISP <> MODEM - NAT IP's - LINKSYS ROUTER/NAT Private IP's (works good)

But mostly the right hand side is just stupid (but yes it will
work, as I said above, but that MODEM better be a NAT.

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