Consumer-grade dual-homed connectivity options?

At home, I currently run two DSL lines. Right now, we just have two
separate LANs, one connected to each line, with my wife's devices attached
to one, and my devices attached to the other. For a while now, I've been
thinking about setting up a load-balancing routing solution to give both
of us access to both lines.

You would need at least one router for this.

Personally I would connect both DSL modems into a small Cisco router or
multi-layer switch. Use that router as the default gateways for each LAN
and have two static routes as the default gateway on the router to
specify each DSL line. This would allow for load balancing each connection.

Although, you run into the issue of needing PAT on both lines. This
wouldn't be complex, but would need to be handled by the router as well.

I am not sure about asymmetric paths though. Depending on the device, it
may handle this differently, and there is no guarantee that the source
of your traffic will be from the same connection all the time to the
destination. This would cause connectivity issues. There really is no
elegant solution to that without having a full routing table of the
Internet and 2 separate providers. Others on this list may have a
solution to that issue off the top of their heads, or have done this

Most of the SOHO router vendors (Netgear, Linksys, etc) have a model
targeted at this application. When this class of "dual homed" router
first came out several years ago, they were notoriously unreliable, but
I would hope they work better by now. A search on the term "ping based
routing" should give you insight into the current state of affairs,
although it will probably take some work because there is no standard
terminology to describe the facility, and most implementations no longer
rely on "ping" to do the job of detecting link status.

A few limitations to keep in mind:

1 - These routers are targeted at home users, are cheap, and you don't
get what you don't pay for.

2 - The job can be done using "real" routers (Cisco, Juniper, etc), but
setup requires work and getting a solution that actually works can be

3 - Be wary of any advice that you get from anyone who has not actually
done it on the box in question! There are many ways a solution which
should work will fail miserably. For example, when I looked at this
problem a few years ago for a client, the SOHO routers tended to lock up
and require a power cycle every few days while Cisco IOS routers would
not clear the NAT table when a link failed soft and tended to stop
testing a link once it failed, requiring manual recovery.

Good luck and have fun!

The SonicWALL firewall appliances have had decent multi-port NAT functionality for a long time. In the most recent software revision for the latest generation of appliances, they've extended this beyond 2 upstreams. The smaller units in the line also can use various 3G wireless cards and USB dongles to either load balance or do failover.

Models range from SOHO-sized to large enterprise. I've used them myself for years, and installed them for clients. They are reliable and straightforward to configure. And yes, for full disclosure, I've been certified on their gear for a long time, and do resell it (also resell several other brands of networking gear).