Re: ICS questions and confusion
- From: DWalker <none@xxxxxxxx>
- Date: Fri, 19 Aug 2005 10:01:52 -0700
Subject: Re: ICS questions and confusion
Newsgroups: Microsoft:microsoft.public.windowsxp.network_web
To: "N. Miller" <2005MS4-18.spam@xxxxxxxxxxxxxx>
Hi, Nick, thanks for the reply (I was out for a few days). Please see
my responses below.
"N. Miller" <anonymous@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
news:1jk33ds4n7ybv.dlg@xxxxxxxxxxxxxxxxxxxxxxxxx:
> 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.
>
What I meant by "a data modeling standpoint" is just that it's an
attribute of the whole host, not an attribute of one of the connections.
When I do data modeling for customer data, I have to make sure that
things are stored at the right "level" -- customer data at the customer
level, account data at the account level, etc. I claim that "allow
other network users to connect through this computer's Internet
connection" is an attribute of the computer, not of one of its
connections.
>> 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.
Right, that does help, although the wording says "allow other network
users to connect through this computer's Internet connection", not
"allow other network users to connect through this connection".
>
>> 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 *know* that the system can have only one connection at 192.168.0.1.
What I'm *saying* is that the only thing in the whole network that has
address 192.168.0.1 is the very same Ethernet connection that ICS is
going to set up with address 192.168.0.1. I know that my computer has
two connections.
>
>> [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.
>
No. Although the modem defaulted to 192.168.0.1, I changed it to use
192.168.0.254 because I knew that ICS needed 192.168.0.1. Yes, both
adapters are on the same subnet. It's not documented anywhere that this
should not be the case.
>> 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".
You're right, and that way of thinking about it does help. And I
understand the history, but now the docs could be improved...
>
>> 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.
I find that addressing two computers manually is triviel; when DHCP is
on, sometimes there's more than one thing in the system trying to give
out IP addresses. It's not a big deal either way.
>
>> 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.
Yes, I know that.
> 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
No, it's not, as I mentioned above. My modem is at 192.168.0.254.
> 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.
>
Well, after all that, and I do appreciate your suggestions...
Why are you so keen on letting my modem/router handle IP address
assignment? There's only one adapter that it's going to see, and like I
said, it's trivial to configure one computer with an address. At work,
where we have 20 computers, I set them all up with DHCP and configured
the Windows server as a DHCP server. (Configuring the Windows DHCP
server service is more work than setting up one computer with a static
IP address, but most routers' DHCP configuration is usually a little
simpler than Windows'.)
The address conflict message that complains that some other device is at
*address* 192.168.0.1, really means that some other device is in the
same *subbnet* as 192.168.0.1; specifically, the LAN adapter that I
should be calling the Internet adapter was in the same subnet. The
message is simply wrong. Telling me that another device in the system
is already using *address* 192.168.0.1 when that is not the case is
simply wrong. A device being on the same subnet is not the same concept
as a device already having that specific *address*. The modem is at
192.168.09.254
----
And the problem was, in fact, the subnets; things actually worked fine
when I changed the subnet of the Internet adapter as you suggested.
Again, I maintain that it's not documented anywhere that the two
adapters should be on different subnets. If I were a networking expert
instead of just a programming expert, then maybe that would be obvious
to me. But with all the documentation out there, someone should at
least mention that issue in passing!
Thanks again.
David Walker
.
- References:
- ICS questions and confusion
- From: DWalker
- Re: ICS questions and confusion
- From: N. Miller
- ICS questions and confusion
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