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Thread: dual WAN router

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  1. #1

    dual WAN router

    I need to know if and how its is possible to to set up a dual WAN router with outbound and inbound load sharing via Linux. I'm a semi-newbie I suppose, I can set up a normal router perfectly fine, but I don't really know where to start with something like this. I tried searching in the forums, but came up fairly empty handed. Any help would be appreciated.

  2. #2
    Linux Enthusiast
    Join Date
    Feb 2005
    SE, Stockholm
    How do you plan to implement this?
    I.e. 2 routers connected to it's own ISP?
    This would be quite impossible with todays IPv4 structure,
    what you can do, is to implement some kind of Policy-Based routing, where you could direct a certain IP:service over one ISP, and some others over the other. That would give you a kind of Semi-functional load-sharing.
    What also could be possible, but don't take it to much, since I have not seen any of those implementations in a none commercal products, would be that you should have a setup like this:
    Internal Net - [R1] - [R2] - ISP1
                            +--- [R3] - ISP2
    Where R1 should have full controll of bandwith usage of both R2 and R3,
    and choose new outgoing connections on the least used R2 or R3 router.
    But as I said, never seen this kind of function in any none comercial product.
    If you want this kind of feature, I believe that you would have to write your own solution
    based on several projects.

    Why would it be a problem?
    Due to the connection state in TCP, all return packets need to come from one and the same IP address. And further on, if you plan to have public hosts which you wish to load share over both ISP's you will not be able to handle this without a PI address range.
    (PI == Provider Independent). But this would not be a 100% perfect solution either, since the initiator would just choose the routing into your network with the lowest cost.
    And it is kind of hard to handle that dynamicly.

  3. #3

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  5. #4
    I am a newbie as well. cause im not sure what you where just talking about there swemic. but i think rfusca is talking a bout a router that will accept two active lines from an ISP, basically if you have cable youd get two active lines run into two sepreate modems in your house with seperate ip addsresses, and if DSL youd have two modems logging into two seperate accounts two to gain different IP addresses. i think that is what he is talking about. but im not sure.
    as for load sharing, the only thing you would be spliting is how requests reach and leave your network. this could improve some of the network traffic, depending on if your requests are being split between the two wan lines, which you would have no control over as requesties reach you by way of routing protocols you have no control over. unless you direct some of the requests(or certain requests) from one WAN IP to the other WAN ip, which im not sure if or how you could do this.
    And now i have a question maybe someone else would answer pertaining to this. If this is done, if they had an internet domain name would they have to pay more for having their domain having two differnt physical ip addresses, like yahoo and google.


  6. #5
    yes, basically take two internet connections, and then divide and balance the load across the two so that you could send it out across a network as one
    it CAN be done with a dual WAN router and surely it is capable to do it in Linux, supposedly the difficult part is balancing the incoming traffic, while the outgong balance is more difficult which implies to me that they must be done rather differently? I don't know.

    If nobody knows how to do this, does anybody know how to set up a router with two connections, one as a failsafe backup on the other so that it will automatically switch to route. basically you have two connections come in, the router uses connection1 until it dies and automatically switches to connection2 and if it dies, tries to go back to connection 1, etc...

    I have access to multiple wired and wireless networks and I would be beautiful to combine them in nicer ways than just letting them go un-used

  7. #6
    look, lol, its like having a house with two mail boxes. unless somone else lives there, there is no need.

  8. #7

    Xincom Solution

    I bought a Xincom a few weeks ago. They make it sound like the perfect solution but after starting to set it up I realized that it is limited in capacity unless you want it for home use.

    I run 20 web sites from my location. The Xincom only supports 10 A records.

    I currently have 1 wireless feed to the building and really need to add a second for redundency. Inbound and outbound load balancing with failover would be a plus.

    I have not found anything commercially available for the price I'm willing to pay. One would think that a Linux solution would be available somewhere.

    Here is an article that I found interesting:

    I am also open to suggestions.

  9. #8
    Linux Newbie
    Join Date
    Jun 2005
    Whitstable, Kent, England
    Take a look at this:

    You will see a link in the bottom-right which shows how to make a Linux box do it for you.
    The biggest security threat is the user.

  10. #9


    That is an interesting solution, however at my present location adsl is not an option either, just wireless or dial-up.

    I'm still open to suggestions.

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