[97415] in RedHat Linux List
Re: Dual Modems & Dial in connectivity.
daemon@ATHENA.MIT.EDU (Ramon Gandia)
Tue Nov 3 03:56:26 1998
Date: Mon, 02 Nov 1998 23:53:01 -0900
From: Ramon Gandia <rfg@nook.net>
To: ccyr@home.com, redhat-list@redhat.com
Resent-From: redhat-list@redhat.com
Reply-To: redhat-list@redhat.com
ccyr@home.com wrote:
>
> Hello, I am looking for information on two topics.
>
> 1) Dual/Piggy-backed modems:
> I read some info somewhere about doing this, but am unsure of where I saw it.
> Linux is supposed to have a software version of this. I want the two modems
> to connect to the Internet and use the cumulative bandwidth for all requests.
> This should also be a dial on demand process which should all be documented in
> the PPP how-to (I didn't see the dual modems there).
It must be set up at BOTH ends, of course. It is know as
MultiLink-PPP. Originally for ISDN modems to get 128K, it
also works, somewhat, for the 33.6K/56K modems. Livingston
servers support it, but it has to be set up by the ISP for
each user (or globally for all, I suppose).
There is another gadget, which is a DUAL modem. It has
ONE serial port, two telephone lines. At the ISP you have to
install a similar unit. You of course have to pay for the
phone lines at both ends because it dials the specific numbers
for that particular modem. I can see how this is attractive
to users, but as an ISP I am not thrilled at all.
However, the Multilink PPP is viable, and it will work regardless
of which phone line your call comes in on. In other words, the
equipment at the ISP will recognize your second call as being
the second half of the MLPPP and set it up that way.
Beats me how you set up the user end in Win 95/Mac/Linux.....
but the MLPPP protocol *is* available for Linux. This would
probably work okay for a Linux box acting as a Gateway/Router
for an office.
Another approach, is to use the WebRamp M3 office router. This
one has an ethernet hub on one side, a DHCP server, and it is
set up via a Web interface. On the other side it has three
serial ports where you can hook up one, two or three modems
of the external 33.6K or 56K variety. Each modem and associated
telco line is set up to dial an ISP. It could be the same ISP,
with the same or different login name, or different ISP's.
It does not do MLPPP, but what it does it takes your TCP/IP
pertaining to one "socket" and routes it via one modem, and other
requests go via other modems.
Example: You have four computers hooked to the hub, all running
Netscape. The browsing on computer #1 would go to modem 1,
computer 2 to modem 2, and computers 3 or 4 to modem 3. Lets
say that user on computer #1 opens two web browser windows.
The second window may well go to a different modem. Also, if
there are objects in the page exceeding 4, then they could go
to different modems. This is a simplistic, not technically
super accurate description, but it will do.
While it does not make any one user faster than 33.6K, it does
allow a *lot* of users to share modem lines.
Let me state now that there is a misconception that a 33.6K
link will support one user, and that if you add a second user
you need 67K. This is not true. As an experiment I tried
doing this: four computers routing out via a single modem at
33.6K. Doing massive downloads of 10 MB files, all different,
with one, two or three computers I got 33.6K. With 4 computers
I got about 95%, or say 31K. Since most users do not do
continuous
massive downloads, it is apparent that a single 33.6K modem
will support about 8 average users and all will think that they
have the modem to themselves.
--
Ramon Gandia ==== Sysadmin ==== Nook Net ==== http://www.nook.net
285 West First Avenue rfg@nook.net
P.O. Box 970 tel. 907-443-7575
Nome, Alaska 99762-0970 ======================= fax. 907-443-2487
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