Networking Question

[Ben Scott]

On Fri, Nov 6, 2015 at 9:48 AM, Greg Kettmann <greg at kettmann.com> wrote:
> For various reasons, including reliability, I have two ISP's.  In my
> original configuration I had two Gateways, GW1-192.168.1.1 and
> GW2-192.168.1.2 on one subnet.

  You're better off having a single router, as the sole gateway on
your LAN, and having the router decide which ISP to use.  That's what
routers are for, to choose the best network route.

  If you have multiple local networks for other reasons (e.g., work vs
home, or guests, etc.), apply the same principle to all of them.  One
router, multiple local networks, multiple Internet connections.

  Note that "router" here could be a COTS solution (Cisco, Netgear,
et. al.), or a cheap home gateway running something like DD-WRT, or a
general-purpose computer running Linux or even a BSD.

  If it's simply about having Internet if an ISP goes down, all you
need is a way to detect which ISP is up.  If both ISPs send RIP
advertisements, you just need to run a basic routing daemon.  If not,
you'll need something that can detect what's up and what's not.
Google "dead gateway detection linux".

  If it's a matter of also making the best use of both ISPs when both
are up, that's usually called load balancing.

  If you want certain traffic to go over certain ISPs when possible
(e..g, work stuff uses ISP A, Netflix uses ISP B), that's called
policy routing.

  The http://lartc.org/ site has some good info on both of the latter
two, although it's getting a bit stale from lack-of-updates.

  If you need help configuring some aspect of that, describe which aspect.

-- Ben