I’m looking for a simple device that provides automatic failover
between several different ISPs.

For example, I’d like to be able to
have a couple of DSL-lines, a satellite internet connection and a
dialup internet connection all plugged into a single box and have that
box be able to determine what connections are available/fastest and
route requests accordingly.  Presumably it could also do NAT and act
as a firewall, but that could also be provided by separate
hardware.

Ideally, this would all be a hardware solution, but I’d be
interested in hearing other options, too.  No particular OS or
hardware preferences.

SysMaster have an "advanced router" solution, which is certainly not
simple, and probably not cheap.

http://www.sysmaster.com/s_net_router.htm

Your dial-up modem requirement makes the question rather harder - if
it was just RJ45 jacks to deal with, the answer might be easier.

--seizer-ga

RJ-45 only input would be OK (although not ideal).
The SysMaster would
be good, but I can't seem to get any idea of what the price would be.

Couple of sort-of options:

There are routers that have either serial ports or actual modems
built-in, which can automatically dial-in if a connection is needed
and the WAN (RJ45) port cannot provide one.

Cisco and 3com make high-end switches and routers that have the
ability to use things such as spanning tree protocol and redundant
links in order to reconnect when part of the network goes down,
although I don't think that's what you have in mind.

Something that may work is having a computer setup as a router. You
could use  linux box, or a windows PC that is running software like
Internet Connection Sharing. Having it dial-in whenever the LAN
conneciton is down is very simple, but having it choose among several
high-speed connections could be difficult. I've never really tried.

Let's consider a situation where you have 2 DSL lines and a dial-up
connection:

Situation 1: Both DSL lines are up. Windows would see the high speed
connection and have internet access through one of them. I don't think
the second would ever kick in. In theory. Although the two sources of
an IP address might throw it off.

Situation 2: One of the DSL connections goes down. No problem. Windows
would see the other one and use it.

Situation 3: They both go down. No problem. Windows detects that there
is no LAN connection, and initiates a dial-in connection as needed.


If your 2 DSL lines are coming from the same source, then you may be
able to simply pay them to make your connection redundant, so if one
went down, the other would kick in. This can be done with static links
such as T1/T3 etc. Although if you had 2 DSL lines from one company,
if one went down, chances are all of them in your area are down.

There are really two issues here:

1.) Redundant physical connectivity to multiple Internet providers
2.) Redundant ROUTING of IP addresses!

The previous answers have taken a good stab at #1, but none have even
touched on answering #2.

In order to accomplish #2 you will need to have your own assigned
public IP address space and you will need to run BGP routing protocol
between yourself and your multiple ISPs.  As far as I know, there's no
way around that and frankly, that's a lot harder than having redundant
connections to the Internet.  Think of it this way, while your
computers will still be able to send packets out to the Internet
through the secondary ISP no one will be able to respond to your
packets because your public IPs will be advertised through the
original/primary ISP which is down.

Additionally, you wouldn't want a single box to provide redundant
connectivity to the Internet as that box would then be your single
point of failure.   Also, make sure that your various different types
of Internet connectivity take seperate physical routes outside of your
facility.  No point in having DSL, T1, and dialup if they all end up
being transmitted on the fiber bundle 25m from your front door.

I would suggest looking at InterNAP (www.internap.com).  They provide
Internet access from their POP over multiple ISPs thereby eliminating
most of the congestion and downtime issues you have from having a
single ISP.

Two Cisco 2600 routers, two T1 lines through diffrent providers (MFS &
your local telco), BGP config by Internap and you're ready to go.

I hope that helps,

Marc

one possible solution is this router with two wan ports, which could
provide you with two internet connections for failover and performance
benefits:

http://www.newegg.com/app/viewproduct.asp?DEPA=&submit=Go&description=Nexland
(product at the bottom, with 2 wan ports and 8 port switch $350)

A friend of mine was considering buying one, so it came to mind.