Maybe this is a reasonable place to ask for some advice: I have 2 broadband connections, one via my phone line (ADSL) (76/17) and one cable (50/4) does anyone have any experience with using 1 piece of hardware to manage them both, possibly load balancing (not important, but would be cool)? I currently have 1 modem and 2 routers... it's not a very power efficient set up, it's also a bad experience because they're all ISP provided and don't allow me to control DNS.
Realistically, you'd be looking at a soho (small office/home office) load balancing router, specifically a dual-wan router. Cisco offers some [1] as well as Peplink [2]. I don't have a lot of experience with them (did some research on it a few years ago but never pulled the trigger), so YMMV when it comes to custom firmware etc. Doing a google search on "dual wan router" would give you a good feel for the environment. It's possible to find them under $200USD. $350 isn't entirely out of the question depending on the features you're looking for.
If you're outside of the US (I'm guessing, based on the speed of your link), some products are export-restricted. You'd have to check on support for your locale. Another option if you're in a DIY mood is making a custom Linux box using split access features of iptables [3].
If you don't want to mess with iptables, ClearOS (CentOS derivative) [1] has built-in multi-WAN support [2], including auto-failover and load balancing. There's a GUI, but you can always SSH in and configure things manually.
My home router/server is a MicroATX box with an Atom D525, 4GB RAM, 2 x 1TB RAID-1, and 2 x Gigabit NIC. Cost a few hundred dollars to build, draws ~16W idle, and is almost silent. DNS, SSH, FTP, SMB, POP/IMAP, SMTP, QoS, PPTP/OpenVPN/IPsec, and dmcrypt are included. The Atom chip is fine for home use, move up to an Athlon if you're pushing a lot of SSH traffic.
I've been doing this for years as well. I use PCengines ALIX boards to build new ones for friends and family now as they seem to have the same specs for half the price.
I'm not sure about your cable connection but if something similar to a Draytek Vigor 120 ADSL ethernet bridge modem exists for it, you could just build a linux box, stick 3 nics in it (one for each bridging modem and the third facing your internal network) and use that as your router.
You just bond the two public facing nics together with ifenslave, setup pppoe and write an iptables script.
Also, IIRC (been a while since I did it), normal bonding only gives you round robbin i.e. your max speed is limited to the bandwidth of whichever external link your connection is forwarded through at the time (unless you use an ISP that can do MLPPP - which is rare). If you want to combine the bandwidth of both connections into one fat virtual pipe, you could get a cheap VPS and then run an Open VPN link over the bonded virtual interface on your linux box at home to the VPS box (I think! I last played with this 4 yrs ago and details are hazy...).
I've done this with Soekris and Cisco. The tricky part is getting a router that will take a cable modem module (not sure if either Soekris or Cisco will), plus a DSL terminator (both Soekris and Cisco will). These are not consumer tech, and they're not cheap.
Then you have to get or guess the configs for both WAN links, possibly with unhelpful residential support techs.
Cisco 2600 class routers are power hungry and loud too, so no win there. Soekris is smaller and more efficient, and runs BSD, so it's awesome in other ways...but it is a pain in the neck to set up. Several hours of prep plus work for your first time.
But if you are most concerned about DNS, I can think of two quick options: put your own router (ideally running Tomato or DD-WRT) behind your existing mess and serve DHCP from there to your network(s), or take DHCP from your provider, but hardcode the DNS settings on each host.
Edit: and Aside: less than a minute after posting this, I decided to check google to see if Soekris supported cable modem cards, and my post (this comment) came up on the first page of results. I had no idea google could turn crawls into results that quickly.
But it appears that Soekris does not support cable modem cards, from a cursory investigation.
> The tricky part is getting a router that will take ...
Or if you're lucky enough for your provided devices to support real bridge, put both of your devices in dumb mode and plug that as ethernet into your dual-wan device. That's still hardware present but management is kept to the absolute minimum. Plus sometimes you don't really have a choice to use the provided devices...
BTW, do yourself a favor and don't get a Zyxel device.
