I did CCNA a long, long time ago at school, and now I need to use it. But as you know, you forget things quite easily when not using them. :P

Ok, I need a router that is able to be connected to 2 WAN ISP's and to the LAN (duh), so that when one WAN connection fails, the other one will take over, or that they divide the load evenly or something like that.

But now I see the routers coming with ADSL, DSL. I have three connections available: 1 cable internet, 1 DSL, and 1 ADSL. Can anyone explain to me which router is able to take two WAN connections? Or tell me what to do best in this situation?

I see that Cisco has a new series 1800, 2800, etc. But I come from the 2600 and 3600 series times, so it isn't telling me much.

-- EDIT --

I've spoken to a friend of mine in systems and networking, and he suggested that it's also possible to use a layer 3 switch. Connecting two ISP to it from the modems and configuring it so that it will balance the load on both WAN ports when needed. What is the downside of using a layer 3 switch instead of a router?

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  • What is the budget and load requirements. Some of Cisco's small business products do what you want out of the box. I have used the ones with two WAN ports but not three though. – Mahdi Jan 15 '15 at 19:08

What you need is WAN aggregation. A simple explanation would be: you would have router 1(dsl) feed into it and router 2 (cable) feed into it. The device will handle communications between the different WANS and send traffic to the device with the least amount of utilization it will also offer fail over if one of them goes down.

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My company is currently looking into Fat pipe, and their diagram is posted above, here is a link to the product I referenced. There are qutie a few other options out there but we settled on Fatpipe because their pricing was good. Realize this technology is pretty expensive and quite difficult to setup but it is exactly what you are looking for.

  • Thx for the answer. Is this not posible by combining three routers, 2 connected to an ISP and both connected to the third router that handles LAN and balances the WAN connections? – Sven van Zoelen Apr 27 '11 at 10:41
  • @sven There may be routers that can do this with dd-wrt however it's not nearly as efficient. Also the way it handles dns lookups is important in a domain environment. – Not Kyle stop stalking me Apr 27 '11 at 11:43

Traditionally this would be done with BGP to select the WAN interface that was closest to the destination.

Very few, if any, ISPs provide BGP facilities to consumers through ADSL or cable.

You can get some routers that do fancy things with routing tables to split the traffic 50/50 between the interfaces on a per-IP basis, but I don't know of any specifics at the moment.

Alot of people who want this kind of functionality create their own Linux based routers. There's lots of resources on the web to learn how to do load balancing with iptables or ipchains in Linux.

  • 1
    Hey Matt I'm a little confused here... What would border gateway protocol have to do with this? I feel like the OP simply needs a WAN aggregator... – Not Kyle stop stalking me Apr 26 '11 at 13:54
  • A WAN Aggregator is basically what I was hinting at with the "you can get some routers that do fancy things". BGP would know which of the connections had the shortest route to the destination IP by what networks the BGP peers were announcing. – Majenko Apr 26 '11 at 14:25
  • True but that brings us back to your original point BGP facilties are basically non existent on consumer grade ADSL and cable. but you are right... confusion cleared up. – Not Kyle stop stalking me Apr 26 '11 at 14:36

With something like a Draytek 2820 router + Additional ADSL modem (or another dual-WAN router) you can connect the router to two independent ADSL services and it will load balance (outbound) between them. For inbound routing you could use a 'net-based service that provides DNS failover/load balancing.


I think all the other solutions suggested will work, but they are all quite expensive, or at least more expensive than my solution. If you get a DD-WRT capable router you can set it up for dual WAN with one WAN as backup, or as dual WAN in a load balanced setup. The latter would essentially "combine" the bandwidth of the two WAN connections, but the the result would not be cumulative (i.e. 10Mbps down on one WAN and 5Mbps down on the other does not equal 15Mbps down, it just means you have more throughput available). I have never personally done this, but I know a guy who did it with four cable WAN connections a couple of years ago using uncapped modems and one old school WRT-54G and he was getting nearly 90Mbps down on good days :) With the increase of speeds that ISPs are offering these days that 90Mbps would be considerably higher.

  • It is for a company of 50+ employees. I have the WRT-54G at home and i like it. But sometimes it craches or kills my internet connection :S custom firmware btw. – Sven van Zoelen Apr 27 '11 at 10:44

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