dual ISP inbound, correct router to get

Posted on 2011-05-11
Last Modified: 2012-05-11
we have two diff ISP's bringing in broadband to our office.  we have comcast on one side and AT&T on the other.  what we hope to do is be up even if one of those providers is down.  we also would like to use all of the bandwidth provided by both of these providers.

my question is what to plug that into.  I know sonicwall offers devices (as well as other vendors) that allow dual WAN ports for failover, but that's not exactly what I'm looking for.  I'd like to set up two diff MX records so that if mail fails to reach us on one IP, it will come in on the other IP.  I'd like my outbound traffic to use ISP one unless it's busy and then bounce over to ISP two.  kind of like bonded T1's do, ya know.

what are your thoughts?



PS: please feel free to ask me questions too in order to better understand what I want.
Question by:crp0499
    LVL 14

    Expert Comment

    by:Juan Ocasio
    You could just set up MX priorities to do this, I believe.  One record will point to one WAN IP address, the other will point to the other one.  Internally in the router, they'll point to the same Exchange Server

    Author Comment

    true, but the standard, off-the-shelf dual bandwidth routers i see let you set up a split like an 80/20 split or round robin type usage.  I need one that leaves both inbound open and at 100% all the time, accepting and directing traffic all the time.
    LVL 20

    Accepted Solution

    You can achieve what you want using a Sonicwall. They provide failover, load balancing, or load settings based upon other parameters for use of both ISP's. As far as email, you have to do as indicated above. Set up one isp as your primary MX record with a priority of 10 and the other MX record with a priority of 20. If the primary is down or otherwise unavailable, the email will bounce to the other. On the LAN side both point to same mail server.

    Author Comment

    you know, I "thought" that about the sonicwall but when I set it up that way, it doesn't actually work and sonciwall support tells me it doesn't actually work that way.  They way sonicwall explained it to me is that WAN2 only "listens" if WAN1 is down.  I'd like both to be UP and active all the time, listening and handling traffic all the time.

    In a production environ, when we set up our sonicwall with dual ISP's, our internet traffic came to a crawl.  SW tech supp told us the two WANS were not always UP and that traffic would only come in on one WAN port at a time.

    LVL 20

    Expert Comment

    Not sure what you are doing, but we have an NSA4500 configured with two WAN interfaces and two ISP's, and it works all the time like advertised. email works fine with both using the priority scheme indicated.

    Exactly what do you mean by "listens"? Also what do you mean by your "internet traffic" came to a crawl. Is this outgoing browsing from you LAN or something else.
    LVL 44

    Expert Comment

    by:Craig Beck
    If you use load-balancing you might get problems with HTTPS sites.  If you can, set HTTPS traffic to use one line only.

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