The wireless router arrived yesterday and the DSL activation happened on time so that the line came up first time when I plugged the line into the router. I'd heard a few horror stories about Orange's support for Macs so I was pleasantly surprised when I popped the install CD into my MacBook and it came with full OSX installation instructions. 5 minutes later I was surfing on the internet via my shiny new Orange broadband.
Now that we had two internet accesses functioning, how to use them both?
I originally thought that I would keep our 8 Mbit business broadband link and the new line on separate networks so that I would not have to change any server or client configurations, just point my test machines at the new default gateway.
However, with a little thinking about how much work it would be to switch all clients over in the event of a line failure (it does happen), especially if no IT savvy people were available at the time of failure, I started Googling for suggestions on how to link all computers to both gateway routers.
I investigated using a spare Linksys router with new firmware to act as a load balancer, but that would introduce a new single point of failure. After thinking a bit more about OSX's multihoming feature I decided to do the following:
- At each Mac, clients and servers, add a new interface (System Preferences » Network » Show Network Port Configurations » New.) I called ours orange internet, using port 'Built-in ethernet.'
- Set up the new port with 'Configure IPv4: Manually,' giving it a 192.168.1.x address. (The original LAN address range is 192.168.0.1, mask 255.255.255.0, and default gateway is 192.168.0.1.)
- On each machine, arrange the order of ports so that the default ethernet for each is first in the list.
- On the server, setup a new DNS zone on 192.168.1.x with the same config as the original.
- Optional: Use dyDNS or similar to assign a domain to the new external IP
[robg adds: My apologies to pglock; this hint was submitted a longgg time ago. For some reason, I marked it as a draft, then forgot about it. Yikes. There's a much older variation on this hint in the system, but this one contains updated information.]

