alt.certification.network-plus

Author

2computers 1...

Ifi

2002-10-29, 5:24 pm

i'm connected with telewest. i've got the motorola sb4200 surfboard cable
modem. it's attached to my computer via the usb port. can i connect 2
computers to the modem and use the net simultaneously. 1 computer will use
the usb port on the modem and the other the rj45 port. i've got no router or
hub.

thanking you in advance

Tessier

2002-10-29, 6:24 pm

Hello,

I did the same thing when I lived in Florida with a Time Warner cable box. I
hooked my desktop via rj-45 and my laptop through the USB and both worked
simultaneously. I don't see why it wouldn't work unless your ISP gets wind
of you using 2 IP address'.

Pat

"Ifi" <In85gf@hotmail.com> wrote in message
news:vfEv9.1453$k6.1287@news-binary.blueyonder.co.uk...
> i'm connected with telewest. i've got the motorola sb4200 surfboard cable
> modem. it's attached to my computer via the usb port. can i connect 2
> computers to the modem and use the net simultaneously. 1 computer will use
> the usb port on the modem and the other the rj45 port. i've got no router
or
> hub.
>
> thanking you in advance
>
>

Barry Watzman

2002-10-29, 7:24 pm

Can't answer the question with regard to your specific situation for
sure, but I can suggest a better understanding of the situation.

Your computers (either or both) are normally configured as "DHCP
Clients". That means that they expect (need) to get ALL of their TCP/IP
settings (IP address, subnet masks, DNS servers, WINS servers, etc.)
automatically from a "DHCP" server.

In most cases (there ARE exceptions), the cable modem is the DHCP server
that gives out IP addresses and other TCP/IP information to the DHCP
clients. However the cable modem is itself a DHCP client to a "master"
DHCP server that serves all, or a part of, the entire cable modem system.

Here's where the rub comes in: Your cable modem can only "give out" IP
addresses that it's been allocated by the cable company. And, in almost
all cases, the cable company only allocates one single IP address to
each cable modem, unless you pay them for multiple addresses (the
typical rate is about $10/address per month, and this is a reasonable
charge because IP addresses are a scarce resource in limited supply).
If the cable modem only has one IP address to give out, and you connect
two computers, only one of them will get an IP address, and the other
computer will be non-functional. There is also a separate question,
which I can't answer, of whether or not the two ports (the RJ-45 port
and the USB port) can be used simultaneously and independently, not
withstanding the issue of IP addresses. The answer to that, of course,
depends on the make an model of the modem, PLUS the cable company's
programming and use of it. One final point here, the issue of number of
ports (e.g. RJ-45 and USB) and allocation of IP addresses are
independent: The same issues exist in a cable modem with only an RJ-45
port connected to a simple hub, to which some number of computers are
connected. In that scenario, each computer needs it's own IP address,
and if the number of IP addresses that the cable modem can provide (due
to programming by the cable operator) is less than that, all of the
computers can't be used at the same time. In this case, however, they
would all be working through the single RJ-45 port.

There is a solution to this, without regard to what the cable company
did or what their policies are: Get a combination router/switch. Now
the router/switch becomes the DHCP server to all of your computers, and
it, in turn, becomes the DHCP client to the cable modem. However, the
router needs only a single IP address for itself, even if there are
dozens of computers connected to it. This is the best way, and the
"right" way, to connect multiple computers to a cable (or DSL) modem.

There are software programs that will perform the router function within
one of your computers. To set this up, the "master" computer needs TWO
network interfaces (which could be one USB port and one Ethernet port or
two Ethernet ports on two separate Ethernet NIC cards). One goes
directly to the cable modem, which does not connect to anything else.
The other goes to a hub or switch to which each of the other computers
is also connected. While this will work, it's not the best way to do
this: You need a significant amount of software installation and
configuration, the master computer has to be on for any of the other
computers to be used and there are other implications too detailed to go
into here. Bottom line, the right way and the best way to do this is
with a combination router/switch, and these days such devices, which
were $200 not too long ago, are available for under $50 (although you
might choose to spend a bit more for a somewhat better model).

Ifi wrote:
> i'm connected with telewest. i've got the motorola sb4200 surfboard cable
> modem. it's attached to my computer via the usb port. can i connect 2
> computers to the modem and use the net simultaneously. 1 computer will use
> the usb port on the modem and the other the rj45 port. i've got no router or
> hub.
>
> thanking you in advance
>
>

Sarah of Certz.com

2002-10-31, 10:24 pm

On Tue, 29 Oct 2002 22:53:32 -0000, "Ifi" <In85gf@hotmail.com> wrote:

>i'm connected with telewest. i've got the motorola sb4200 surfboard cable
>modem. it's attached to my computer via the usb port. can i connect 2
>computers to the modem and use the net simultaneously. 1 computer will use
>the usb port on the modem and the other the rj45 port. i've got no router or
>hub.
>
>thanking you in advance
>

Depends on type of service, if its single user, then its locked to the
MAC address of the first NIC in your PC.

If I were U, I'd get a router for which you can set the MAC address
that will be visible to the Cable modem such as the d-link di-804

Sarah
http://www.certz.com
IT Certification Routes website
(a www.walsoft.net network service)

Barry Watzman

2002-10-31, 10:24 pm

Sara,

Often (I'd say usually), the cable or DSL ISP does NOT care about the
MAC address. While the situation that you describe does sometimes
happen (it all depends on the type of service, as you correctly state),
I think that the more common situation is a bit different than what you
described.

When using a cable or DSL modem, the cable or DSL modem is acting as a
DHCP server to whatever is connected to it. However, MAC address
entirely aside, in most cases the ISP has programmed the modem to
provide only a single IP address. Consequently, when multiple computers
are hooked up, it fails not because of the MAC address, but simply
because it's being asked for more IP addresses than it has available to
give out (which is usually one and only one).

The solution is to use some form of NAT, which may be either a router or
a computer with multiple network interfaces and appropriate connection
sharing software properly configured. The router is the better choice,
and almost all of them do support "MAC address cloning" as you
described, for just the reason that you described. However, more often
than not (but definitely with exceptions), the failure is not because
the ISP cares about the actual MAC address, but because there are
multiple devices asking for an IP address from a DHCP server that has
only a single address to give out.

Sarah of Certz.com wrote:
> On Tue, 29 Oct 2002 22:53:32 -0000, "Ifi" <In85gf@hotmail.com> wrote:
>
>
>>i'm connected with telewest. i've got the motorola sb4200 surfboard cable
>>modem. it's attached to my computer via the usb port. can i connect 2
>>computers to the modem and use the net simultaneously. 1 computer will use
>>the usb port on the modem and the other the rj45 port. i've got no router or
>>hub.
>>
>>thanking you in advance
>>
>
>
> Depends on type of service, if its single user, then its locked to the
> MAC address of the first NIC in your PC.
>
> If I were U, I'd get a router for which you can set the MAC address
> that will be visible to the Cable modem such as the d-link di-804
>
>
>
>
>
> Sarah
> http://www.certz.com
> IT Certification Routes website
> (a www.walsoft.net network service)

Sarah of Certz.com

2002-11-01, 12:24 am

On Fri, 01 Nov 2002 04:09:46 GMT, Barry Watzman <Watzman@neo.rr.com>
wrote:

Hi

Yes, I agree that a router apart from supplying a single MAC address
also acts as a NAT. In the UK, I personally know that telewest (the
cable provider), do lock to the NIC's MAC address for single IP
address service.

>The solution is to use some form of NAT, which may be either a router or
>a computer with multiple network interfaces and appropriate connection
>sharing software properly configured. The router is the better choice,
>and almost all of them do support "MAC address cloning" as you
>described, for just the reason that you described. However, more often
>than not (but definitely with exceptions), the failure is not because
>the ISP cares about the actual MAC address, but because there are
>multiple devices asking for an IP address from a DHCP server that has
>only a single address to give out.
>
>
>Sarah of Certz.com wrote:
>> On Tue, 29 Oct 2002 22:53:32 -0000, "Ifi" <In85gf@hotmail.com> wrote:
>>
>>
>>>i'm connected with telewest. i've got the motorola sb4200 surfboard cable
>>>modem. it's attached to my computer via the usb port. can i connect 2
>>>computers to the modem and use the net simultaneously. 1 computer will use
>>>the usb port on the modem and the other the rj45 port. i've got no router or
>>>hub.
>>>
>>>thanking you in advance
>>>
>>
>>
>> Depends on type of service, if its single user, then its locked to the
>> MAC address of the first NIC in your PC.
>>
>> If I were U, I'd get a router for which you can set the MAC address
>> that will be visible to the Cable modem such as the d-link di-804
>>
>>
>>
>>
>>
>> Sarah
>> http://www.certz.com
>> IT Certification Routes website
>> (a www.walsoft.net network service)

Sarah
http://www.certz.com
IT Certification Routes website
(www.walsoft.net network service)

>Pearl Jam

2002-11-06, 3:24 pm

On Fri, 01 Nov 2002 03:33:57 +0000, Sarah of Certz.com
<admin@no-usenet-emails.com> wrote:

>On Tue, 29 Oct 2002 22:53:32 -0000, "Ifi" <In85gf@hotmail.com> wrote:
>
>>i'm connected with telewest. i've got the motorola sb4200 surfboard cable
>>modem. it's attached to my computer via the usb port. can i connect 2
>>computers to the modem and use the net simultaneously. 1 computer will use
>>the usb port on the modem and the other the rj45 port. i've got no router or
>>hub.
>>
>>thanking you in advance
>>
>
>Depends on type of service, if its single user, then its locked to the
>MAC address of the first NIC in your PC.
>
>If I were U, I'd get a router for which you can set the MAC address
>that will be visible to the Cable modem such as the d-link di-804

Or even the LinkSys BEFSR41 will allow you to do that as well... the
one with the newer bios revision, if not, just download the new flash
and do it yourself... which is what I had to do... but not cuz I
needed the MAC programmable feature.

>
>Sarah
>http://www.certz.com
>IT Certification Routes website
>(a www.walsoft.net network service)

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