Very Computer

I would like to purchase a permanent connection to the Internet to allow our
internal network to access the Internet.  I know I could use one 33.6 modem
but I don't believe this will be fast enough for our needs.  ISDN is not an
option because here in Australia ISDN is VERY expensive.  What I want to find
out was if it is possible to run Linux with two 33.6k modems (two different IP
addresses) and run 2 default gateways (one out each modem) with some type of
switching between each gateway based on the load on each modem.  I think that
this would effectively give 67.2kbps which would be comparable to a basic 64k
ISDN line.

Thanks,

Andrew Wild

Quote:>I would like to purchase a permanent connection to the Internet to allow our
>internal network to access the Internet.  I know I could use one 33.6 modem
>but I don't believe this will be fast enough for our needs.  ISDN is not an
>option because here in Australia ISDN is VERY expensive.  What I want to find
>out was if it is possible to run Linux with two 33.6k modems (two different IP
>addresses) and run 2 default gateways (one out each modem) with some type of
>switching between each gateway based on the load on each modem.  I think that
>this would effectively give 67.2kbps which would be comparable to a basic 64k
>ISDN line.

A software solution to simply route data evenly through two distinct modem
connections and IP's is potentially do-able, but will yield a max bandwidth
for a single user of 33.6K (for up to two users) - a single user won't be
able to grab it all for a single process.  

There exists load-balancing software for Linux, which would provide double
bandwidth over two (perhaps more?) modems with a single IP address, but
your ISP would need a similar setup on their end - something they probably
won't be willing to set up on their internal network.  

You might be able to build a Linux box to do your inverse multiplexing and
load balancing (single IP address), which the ISP would allow you to
connect to their network, so they could route to it as the default gateway
for your internal network, and you'd have a similar box connected to your
local network.  Depending on the price of PC's in Australia, the Netblazers
(or other inverse multiplexer) might be cheaper, and will certainly be
simpler.

| I would like to purchase a permanent connection to the Internet to allow our
| internal network to access the Internet.  I know I could use one 33.6 modem
| but I don't believe this will be fast enough for our needs.  ISDN is not an
| option because here in Australia ISDN is VERY expensive.  What I want to find
| out was if it is possible to run Linux with two 33.6k modems (two different IP
| addresses) and run 2 default gateways (one out each modem) with some type of
| switching between each gateway based on the load on each modem.

Multiple defaults will require custom code in the kernel, and of
course you will only be able to get 33k6 between your host and any
other host because the load won't share between multiple IP
addresses. You will have to ensure that once you use one "default"
to talk to a remote host that you always use the same IP for that
host, to avoid confusing routing.

Personally I would live with one IP address for both modems and
share the load and bandwidth between them with the standard EQL
option built into the kernel.
--

"As a software development model, Anarchy does not scale well."
                -Dave Welch

|

| >                                                          What I want to find
| >out was if it is possible to run Linux with two 33.6k modems (two different IP
| >addresses) and run 2 default gateways (one out each modem) with some type of
| >switching between each gateway based on the load on each modem.  I think that
| >this would effectively give 67.2kbps which would be comparable to a basic 64k
| >ISDN line.
|
| There is a hardware solution to your dilemma - inverse multiplexing.  The
| Telebit Netblazer, for instance, will support 2 serial connections (with
| dial-on-demand and load-levelling) and effectively give you the full
| bandwidth of both modems with a single IP address.  The catch?  You need 2
| Netblazers, and four modems.

But he wants two IP addresses. If he only needed one IP address he
would have used the EQL built into the kernel, needing only the
modems. The hard part of this is using two IP addresses as
"default," since load sharing is a standard feature.
--

"As a software development model, Anarchy does not scale well."
                -Dave Welch

As it stands, two multilinked 33.6ks would give you about half the speed
of a 64k isdn. Although you'd probably make up some ground on compression
since all IAPs here don't offer compression on ISDN linkages.

Quote:>| There is a hardware solution to your dilemma - inverse multiplexing.  The
>| Telebit Netblazer, for instance, will support 2 serial connections (with
>| dial-on-demand and load-levelling) and effectively give you the full
>| bandwidth of both modems with a single IP address.  The catch?  You need 2
>| Netblazers, and four modems.

>But he wants two IP addresses. If he only needed one IP address he
>would have used the EQL built into the kernel, needing only the
>modems. The hard part of this is using two IP addresses as
>"default," since load sharing is a standard feature.

Quote:>A software solution to simply route data evenly through two distinct modem
>connections and IP's is potentially do-able, but will yield a max bandwidth
>for a single user of 33.6K (for up to two users) - a single user won't be
>able to grab it all for a single process.  

 AW> I would like to purchase a permanent connection to the Internet to allow
 AW> our internal network to access the Internet.  I know I could use one 33.6
 AW> modem but I don't believe this will be fast enough for our needs.  ISDN is
 AW> not an option because here in Australia ISDN is VERY expensive.  What I
 AW> want to find out was if it is possible to run Linux with two 33.6k modems
 AW> (two different IP addresses) and run 2 default gateways (one out each
 AW> modem) with some type of switching between each gateway based on the load
 AW> on each modem.  I think that this would effectively give 67.2kbps which
 AW> would be comparable to a basic 64k ISDN line.

Use EQL. Its included in the kernel. We use it at *box.north.de for quite a
while. The only part of the system, which make no trouble ;-)

Bye
 Joerg

It is possible to bond the two modems together as one channel, if the term
server you're dialing into supports it.  There is code for this in the kernel
package.  I remember seeing it when I compiled, but I don't remember what it's
called.   It only works if your ISP uses a certain model of Portmaster server,
but if you can get it to work, it would be double bandwidth with only one IP
number and route.

--
-----BEGIN GEEK CODE BLOCK-----  W. Mark Hagler
GCS/E d- s: a--- C++ ULI*+++>$ P+ L++++>$ E--- W+++ N+ o++ K-
w--- O---- M+ V- PS+ PE- Y-- PGP>++ t-- 5 X- R- tv++ b+ DI++++
D G++ e>+++ h r+ y+

| Linux already supports load balancing so you could use your modems in that
| fashion. However, it doesn't support multilink (mppp) (yet?) so you won't
| get a 67.2kbps.

I'm not sure what load balancing vs. mppp might be, but two
connections give about twice the bandwidth of one for many things.
It will not help ping times, and an individual packet will take one
path or the other, but consecutive packets can go in parallel.

| As it stands, two multilinked 33.6ks would give you about half the speed
| of a 64k isdn. Although you'd probably make up some ground on compression
| since all IAPs here don't offer compression on ISDN linkages.

Is this a question of terminology? Obviously individual packets
would be slower, but the aggregate bandwidth should be about equal,
even without compression.
--

"As a software development model, Anarchy does not scale well."
                -Dave Welch