Any reason I can't daisychain a router onto a BT Voyager 205 modem?

Hi,

I was recently helping someone temporarily share someone else's
internet connection (with permission). The owner was originally
connected via a BT Voyager 205 (or 210) ASDL modem, but this only
supports one connection.

As I didn't want to mess with their configuration, I plugged an
Ethernet router/switch into the back of the Voyager (from the router's
WAN socket to the Voyager's single network socket), and in turn
plugged each PC's network cable into the router/switch.

In theory, the Voyager would only "see" one connection and the other
router would split this single connection using NAT and friends. It
seemed to work, but it kept disconnecting. Either there were problems
with the router/switch's DHCP lease from the Voyager, or the Voyager's
ADSL connection/handshake kept failing.

When I put things back the way they were originally, they were fine
again. When we used a single-box ADSL-modem/Internet-router (with both
PCs in the back) it was still fine.

Is there anything about BT Yahoo broadband that would have caused this
problem? I'm really curious because in theory it should have worked.
(I made sure that the Voyager's USB connection was not used- this made
no difference- and that the router was giving out DHCP's on a
different network number to those given out by the Voyager).

- Triffid

On Sun, 16 Sep 2007 14:43:31 -0700, (E-Mail Removed) wrote:

>Hi,
>
>I was recently helping someone temporarily share someone else's
>internet connection (with permission). The owner was originally
>connected via a BT Voyager 205 (or 210) ASDL modem, but this only
>supports one connection.
>
>As I didn't want to mess with their configuration, I plugged an
>Ethernet router/switch into the back of the Voyager (from the router's
>WAN socket to the Voyager's single network socket), and in turn
>plugged each PC's network cable into the router/switch.
>
>In theory, the Voyager would only "see" one connection and the other
>router would split this single connection using NAT and friends. It
>seemed to work, but it kept disconnecting. Either there were problems
>with the router/switch's DHCP lease from the Voyager, or the Voyager's
>ADSL connection/handshake kept failing.
>
>When I put things back the way they were originally, they were fine
>again. When we used a single-box ADSL-modem/Internet-router (with both
>PCs in the back) it was still fine.
>
>Is there anything about BT Yahoo broadband that would have caused this
>problem? I'm really curious because in theory it should have worked.
>(I made sure that the Voyager's USB connection was not used- this made
>no difference- and that the router was giving out DHCP's on a
>different network number to those given out by the Voyager).
>
>- Triffid

The Voyager is a router with NAT/DHCP albeit a with a single port. The
easiest way to would have been to disable DHCP in your router and then
connect the two LAN to LAN so that your router was just being used as
a switch.

(E-Mail Removed) wrote:

> As I didn't want to mess with their configuration, I plugged an
> Ethernet router/switch into the back of the Voyager (from the router's
> WAN socket to the Voyager's single network socket), and in turn
> plugged each PC's network cable into the router/switch.
>
> In theory, the Voyager would only "see" one connection and the other
> router would split this single connection using NAT and friends. It
> seemed to work, but it kept disconnecting. Either there were problems
> with the router/switch's DHCP lease from the Voyager,

Was the Voyager pingable from behind the router when the internet went off?

> or the Voyager's ADSL connection/handshake kept failing.

Odd. Was the Voyager losing sync when the internet went off? Anything in the
Voyager's logs? Is the Voyager's ADSL connection nailed up or
dial-on-demand? It's a long shot, but perhaps the PSU on your ethernet
router is faulty, and generating electrical noise that interferes with the
DSL signal.

> When I put things back the way they were originally, they were fine
> again. When we used a single-box ADSL-modem/Internet-router (with both
> PCs in the back) it was still fine.

Does the ethernet router work behind the single-box
ADSL-modem/Internet-router?

--
<http://ale.cx/> (AIM:troffasky) ((E-Mail Removed))
08:58:30 up 61 days, 14:45, 2 users, load average: 0.10, 0.15, 0.16
09 f9 11 02 9d 74 e3 5b d8 41 56 c5 63 56 88 c0

(E-Mail Removed) wrote:
> Hi,
>
> I was recently helping someone temporarily share someone else's
> internet connection (with permission). The owner was originally
> connected via a BT Voyager 205 (or 210) ASDL modem, but this only
> supports one connection.
>
> As I didn't want to mess with their configuration, I plugged an
> Ethernet router/switch into the back of the Voyager (from the router's
> WAN socket to the Voyager's single network socket), and in turn
> plugged each PC's network cable into the router/switch.
>
> In theory, the Voyager would only "see" one connection and the other
> router would split this single connection using NAT and friends. It
> seemed to work, but it kept disconnecting. Either there were problems
> with the router/switch's DHCP lease from the Voyager, or the Voyager's
> ADSL connection/handshake kept failing.
>
> When I put things back the way they were originally, they were fine
> again. When we used a single-box ADSL-modem/Internet-router (with both
> PCs in the back) it was still fine.
>
> Is there anything about BT Yahoo broadband that would have caused this
> problem? I'm really curious because in theory it should have worked.
> (I made sure that the Voyager's USB connection was not used- this made
> no difference- and that the router was giving out DHCP's on a
> different network number to those given out by the Voyager).
>
> - Triffid
>
Hi Triffid

As Digby says, the probable trouble is that you originally had two DHCP
and NAT (Network address translation) services running.

You could try this - log in to your Voyager 205 and disable DHCP and
NAT (I am guessing that it will then simply operate as an ethernet
modem, which is what your router expects to connect to),

Then the router will provide NAT services and act as the DHCP server.

Mike

On Sep 17, 9:06 am, alexd <troffa...@hotmail.com> wrote:
> trif...@oink.co.uk wrote:
> Was the Voyager pingable from behind the router when the internet went off?

Yes; in fact, the Voyager's web server was accessible when that
happened. I should make clear that the router itself was next door,
and it would have been a PITA for the owners if I popped round every
time I'd wanted to look at the modem :-)

The guy had reported BT having a lot of problems around that time (it
was five or six weeks back), but it just seems strange that it wasn't
half as bad once we ditched the two-box setup

> Odd. Was the Voyager losing sync when the internet went off? Anything in the
> Voyager's logs? Is the Voyager's ADSL connection nailed up or
> dial-on-demand?

No idea, sorry.

> It's a long shot, but perhaps the PSU on your ethernet
> router is faulty, and generating electrical noise that interferes with the
> DSL signal.

It's possible, I guess. I can't check it because we're not using the
setup any more. Thanks for the suggestion anyway!

- Triffid

On Sep 16, 10:55 pm, Digby <a> wrote:
> The Voyager is a router with NAT/DHCP albeit a with a single port.

Yep, I figured that out. I'm not sure why they did that, but I like it
because- if nothing else- it provides Joe Clueless with a moderate
level of implicit firewalling. Which may be the exact reason.

> The
> easiest way to would have been to disable DHCP in your router and then
> connect the two LAN to LAN so that your router was just being used as
> a switch.

Yep, possibly; though as I mention elsewhere, part of the reason for
the daisychaining was to avoid disturbing the existing setup. And in
theory, the way I did it- though clearly not an ideal solution- should
have worked, unless there was something I overlooked.

- Triffid

On Sep 17, 6:48 pm, Mike J <mik...@tiscali.co.uk> wrote:
> As Digby says, the probable trouble is that you originally had two DHCP
> and NAT (Network address translation) services running.

> You could try this - log in to your Voyager 205 and disable DHCP and
> NAT (I am guessing that it will then simply operate as an ethernet
> modem, which is what your router expects to connect to),
>
> Then the router will provide NAT services and act as the DHCP server.

Unfortunately (or rather, fortunately), we have our own connection and
are no longer sharing with the people next door. (And even before
that, we'd had to ditch the setup and go with a single-box solution).

If we were still having to share, I'd have been unhappy about getting
in their way (physically and Internet-wise) even more than I was doing
already. Not to mention that my reason for retaining the modem was so
I didn't have to change the existing setup.

The reason I asked was that it should have worked in theory, and I was
curious as to what the problem was (good opportunity to learn about
networking IMHO). Thanks for the feedback anyway, I'll bear it in mind
in the future

- Triffid

In message <(E-Mail Removed)>
Digby <a> wrote:

>> The owner was originally connected via a BT Voyager 205 (or 210) ASDL
>> modem, but this only supports one connection.

> The Voyager is a router with NAT/DHCP albeit a with a single port.

Waitrose offer a free "Voyager 210 broadband router" which, they tell us,
will "Connect two devices to the Internet simultaneously using the USB
and Ethernet Ports". Somehow I'd imagined that it would allow me to
connect two computers, one with a networking card but no USB, the other
with USB but no networking card. What have I misunderstood?



Chris