Re: ICS questions and confusion

On Mon, 15 Aug 2005 09:44:54 -0700, DWalker wrote:

> I had ICS set up and working fine for a couple of years on a desktop
> computer (the laptop computer in the house used the desktop computer's DSL
> connection).
>
> I upgraded the desktop computer from 2000 to XP, and I ran into two of the
> same issues again. I'd like some comments on these two, if anyone else is
> bothered by the same things that confuse me.
>
> First, when you're on the host computer, and you want to enable sharing of
> the Internet connection, the Advanced tab of the connection has the ICS
> checkbox that says: "Allow other network users to connect through this
> computer's Internet connection". I have always found that wording
> confusing.
>
> It doesn't make it clear which connection icon you should enable this
> checkbox on -- the connection that's cabled to the DSL modem/router, or the
> wireless PCI card, which is the connection THROUGH which the "other network
> users" actually GET to this host computer.
>
> Yes, I want to "allow other network users to connect through this
> computer's Internet connection", but from a data-modeling standpoint, that
> is an attribute of the entire host computer, not an attribute of either of
> the two Ethernet connections on the host computer. Or maybe it is an
> attribute of both of the Ethernet connections involved in the Internet
> connection sharing.

The problem is, this isn't "data modeling", this is a hardware connection;
two hardware connections, really. Each connection has to be uniquely
identified. The one which connects to the laptop is separate from the one
which connects to the DSL modem.

> Whenever I had trouble with ICS before, I would futz around with these
> settings and I could never remember which connection was supposed to have
> the checkmark. Even reading other explanations of how to set up ICS (like
> at practicallynetworked.com), didn't make it completely clear. Maybe it's
> just me.
>
> Comments?

If you start with the notion of connections, and see that your "host"
computer has two of those, maybe it will make more sense? The connection to
the DSL modem is the one which will be shared.

> Secondly, when I had intermittent problems with the laptop accessing the
> Internet in the past, I tried to disable and re-enable this ICS checkbox.
> But I always got the error message that said some other connection on the
> network already had the required address 192.168.0.1. I understand
> completely about this address, and I know that it's given to the LAN
> connection through which the other computers connect to this computer.
>
> The problem is, the "other" connection on the network that already had
> address 192.168.0.1 was the SAME ONE that Windows needs to give that
> address to in order to re-enable ICS. Windows complains that the address
> is occupied by the same adapter to which it wants to give that address to.
> Isn't that stupid?

Not really. There can only be one IP address 192.168.0.1 in the network. If
the "other" connection has that IP address, ICS can't assign it to the
network adapter in the "host" computer. No other connection in the network,
or the computer (two connections, remember?) should have that IP address,
or you can't re-enable ICS.

> [I eventually discovered that I could re-enable a working ICS by disabling
> the LAN connection that goes to the DSL router, turning off the ICS
> checkbox, turning the ICS checkbox back on, then re-enabling the LAN
> connection. I couldn't turn the ICS checkbox back on untless I first
> disabled the LAN connection, and that avoided the stupid message above.
> Has anyone else had to do this to unstick a balky ICS?]

It has been a long while since I used ICS. It sounds like you have both
network adapters set up in the 192.168.0.0/24 network; and ICS is finding
that some device already has the IP address which it wants to assign. Most
likely the modem has that address, so ICS will balk until you disable the
network connection to the modem.

> When you go to turn on ICS, the wording here again is confusing. It says,
> and I quote:
>
> "When Internet Connection Sharing is enabled, your LAN adapter will be set
> to use IP address 192.168.0.1."
>
> The phrase "your LAN adapter" is poorly chosen. I have two LAN adapters --
> one connects to my DSL modem/router, and the other is my wireless PCI card
> that the laptop connects to this computer with. This phrase makes it sound
> like I only have one LAN adapter. Again, I get confused which one is going
> to get address 192.168.0.1 -- the one that's connected to my DSL router, or
> the PCI wireless card?

At the time that was written, most people would have one Ethernet adapter,
and one dial-up modem. They just haven't gotten around to a re-write to
cover the contemporary situation. It helps me to think of the adapter which
has the Internet connection as the "Internet Adapter". The adapter to which
the laptop is attached should be considered the LAN adapter. Now, reading
that instruction again, which is the one that should get IP address
192.168.0.1? The "Internet Adapter"? Or the "LAN Adapter"?

While you have two network adapters, you really only have one "LAN
Adapter"; the other network adapter is the "Internet Adapter".

> Finally, the message goes on to tell you to turn on let the other computers
> on the network get their addresses automatically. I had some trouble with
> this, and finally set the single "other computer[]" on my network to use
> the static address 192.168.0.50. What's the benefit of turning on DHCP for
> the other computer? Is it just to make sure that I know to set up the
> other computer with the same subnet with the right mask?

The advantage of using DHCP is that you don't have to manually track which
device gets which IP address, how DNS is assigned, and so on. It really is
easier to use DHCP; but you have to be sure that the two network adapters
are in different IP address blocks, or DHCP can make a squirrelly situation
get squirrelier.

> Anyway, let me know if anyone agrees or disagrees with my complaints and
> confusion here.

To begin with, you can't have two different networks with the same network
address. Your Internet connection is a different network than your LAN.
Your two network adapters in your "host" computer must have different
network addresses. ICS always uses 192.168.0.0/24, assigning 192.168.0.1 to
the adapter in the ICS, or "gateway", computer. No other device connecting
to that computer can have that IP address, or ICS won't work. Because your
modem is at IP address 192.168.0.1, you will have a problem getting ICS to
work unless you can make some changes. Since you said that you can change
your modem IP address, I would suggest setting it to 192.168.1.1.

Next, you have to differentiate which network does what. That is where you
think of the network adapters as the "Internet Adapter", and the "LAN
Adapter". Having changed your modem IP address to 192.168.1.1, your
"Internet Adapter" should get an IP address from the modem; probably
192.168.1.2, but I don't really know. Which modem is it that you have? BTW,
if you couldn't change the IP address on the modem, you would have to
change it to bridge mode, or you could never get ICS to work.

Now that your "Internet Adapter" is properly configured, you can set up
ICS. When ICS asks which adapter to share, you will check the "Interenet
Adapter". When ICS wants to set the "LAN Adapter" to IP address
192.168.0.1, there will no longer be a conflict. You can let ICS handle
DHCP, now, and tell the laptop to obtain an IP address automatically. The
last time that I set up ICS, each successive computer connected to the LAN
obtained an IP address one higher than the last; the laptop would get
192.168.0.2. And so on.

Finally, is your modem truly a router? It can use DHCP to assign IP
addresses? If so, why not invest $10 - $15 for a switch? Instead of ICS,
let the router component of the modem handle IP address assignment. If the
modem can't do that, you should still be able to use a switch, and just set
the IP addresses of the computers manually, as a static LAN. Then you don't
need to run the "host" computer just to access the Internet.

--
Norman
~Win dain a lotica, En vai tu ri, Si lo ta
~Fin dein a loluca, En dragu a sei lain
~Vi fa-ru les shutai am, En riga-lint
.

Relevant Pages

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    (microsoft.public.windowsxp.network_web)
  • Re: ICS - when needed?
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    (microsoft.public.windowsxp.network_web)
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  • Re: ICS questions and confusion
    ... Subject: ICS questions and confusion ... >> computer's DSL connection). ... I want to "allow other network users to connect through this ... > assign it to the network adapter in the "host" computer. ...
    (microsoft.public.windowsxp.network_web)
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