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I have Verizon DSL in my office, I put DSL in about a year ago for $29.95 month...I added a new phone line recently and it was cheaper to actually get it bundled with DSL so now I have two DSL lines...my plan was to shut the first one off when my 1 year contract comes up (in September).

A couple of times DSL has gone out on one line so I just used the other, which is a nice redundancy to have - but it doesn't happen often. (I unplugged one line and plugged in the other)

Question is, is there any way to use both DSL lines together so that

  1. Increase bandwidth and effective speed might increase (is that possible?)
  2. have them both on and connected someway so that traffic on my network would just use either one, and if one went down the traffic would route automatically?

If I can either increase speed by having two, or at a minimum get some automatic redundancy, I see no reason to keep both on....

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16 Answers 16

up vote 6 down vote accepted

There are "multi-WAN" or "dual WAN" routers that can perform some rudimentary load-balancing and failover using multiple Internet connections. There are a variety of price-points and feature sets, so you'd do well to shop around and compare reviews.

You'll never get the full bandwidth of both Internet connections to be "shared" for a single TCP connection (a single download, etc) w/o cooperation from the ISP on the other end. W/ consumer / prosumer "multi-WAN" routers the best you can hope for is that the router would try and intelligently send new outgoing TCP requests over the less-congested link.

I've seen a couple reviews of these Peplink Balance routers just doing a rudimentary search. They're not inexpensive, but they appear to be fairly solid. There a load of possible candidates, though. Head over to Google and get to searching.

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Regarding your second paragraph, what you say is correct. To be more precise, there is no way to 2 lines from different ISPs for one TCP/IP connection, as the TCP/IP stream would go out over 2 different TCP/IP addresses. This is not a limitation of consumer / prosumer gear, it applies to all equipment. Good prosumer firewalls can spread multiple connections over different lines by a couple of different algorithms: 1) round robin, 2) select least loaded line, or 3) quasi-Quality Of Service, i.e. send certain types of traffic (VoIP calls) over one line, and bulk traffic over the other. –  Jesper Mortensen Aug 25 '09 at 21:51
    
Be sure to check your ISP's terms of service if you start doing this - they may not be happy with what you're trying to achieve. –  Andrew May 17 '10 at 2:51
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Sounds like a good use case for pfSense http://www.pfsense.org/. With pfSense you should be able to accomplish what you want using a MultiWAN setup.

Here are a few links from the pfSense wiki to get you started:

If you have any trouble, check out their "Routing and Multi WAN" forum for additional help: http://forum.pfsense.org/index.php?board=21.0

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pfSense would be a great solution for this, perhaps installed on a tiny SSD harddrive attached to a small, low-power motherboard in the ITX or mini-ATX form factors. You could also use a Soekris or Alix board, but pfSense should ideally have at least some RAM (256 mb or more) and Pentium II class CPU. –  Jesper Mortensen Aug 25 '09 at 21:40
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I couldnt agree more, In the past I have used the Alix 2d3 board with pfSense it was a good solid combination. pcengines.ch/alix2d3.htm –  faultyserver Aug 25 '09 at 22:03
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I'm kind of being redundant here... as a few people have already mentioned this. However, I definitely recommend Peplink's devices. I mentioned this in another answer but we were recently looking around for a multiple wan solution and we first tried the Barracuda Link Balancer as we are happily using their Email and Web filtering solutions. However, the barracuda link balancer is a new solution and wasn't flexible enough to do what we wanted. We bought the Peplink Link Balancer (the 380 version, if you're curious) and we couldn't be happier. It's really versatile and great for our needs. It ended up being a lot cheaper as well. Just looking at the online demo of their interface should give you an idea of all the options you have with it.

We also have a cradelpoint cellular (CRT-250) router hooked up to one of our WAN ports, so in case our primary and secondary internet connection goes down it will switch over to our cellular backup. We even have the peplink configured on this interface with a bandwidth quota, so we won't go over our 5GB allowance on the cellular card and be charged excessive fees.

Of course, depending on how critical the internet is to your business, you may be able to find a cheaper solution that does not have as many bells and whistles.

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I have a similar set up, except I use a cable modem and DSL line. From personal experience I would recommend buying a ALIX.2D3 board(quiet/low power) and enclosure. And then install pfSense which among the many features offers load balancing, failover, multiple WAN. pfSense offers one of the most flexible and complete web interfaces, it should have no problem accomplishing what you want.

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There's a nice product that handles your sort of setup. I have a friend who uses one in his small business and he's pretty happy with it, last I heard: Peplink Balance multi-WAN routers. (http://www.peplink.com/)

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Does the friend use the device that offers 3G connections? –  tomjedrz Aug 25 '09 at 17:37
    
Pretty sure not. He uses it to aggregate bandwidth (and increase reliability to the office) of business DSL and business cable. –  user5336 Aug 25 '09 at 18:33
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Once upon a time, I used an OpenBSD box with pf to load balance accross three lines. If you're the only person working there it's of no real benefit. If there are multiple people there, you'll get some load balancing, although individual downloads won't actually go any faster.

(There's quite possibly a better way of doing this, I'm just mentioning what worked for me at the time)

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try this: http://www.dlink.com/products/?sec=1&pid=452 make sure you upgrade the firmware as this post recommends: http://www.speedguide.net/broadband-view.php?hw=87

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Looks like that D-Link was discontinued 4 months ago. –  Igor Aug 25 '09 at 17:12
    
@Igor oh wow. I was trying to order that before :P –  user14898 Aug 26 '09 at 8:15
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You can also use a ClarkConnect box to load balance multiple WAN connections (once you connect to remotely, the same IP is maintained for the session, although you could be represented by different IPs to different sites). It offers:

  • auto-failover
  • load balanced
  • round-robin based on user-defined weights (see configuration section)

and will run on low end hardware (with multiple NICs).

You won't be able to aggregate the lines without help from your hosting provider however (it's rather expensive too). Balancing means you have a greater total "parallel" bandwidth for your office, but not for a single connection to any one site.

The most redundant option is various different internet connections. And if one of the lines is down and you're using the same provider for both, it's likely the other would be too.

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Good product! The ClarkConnect "Community" edition (free) does not allow this, but the "Enterprise" edition ($85/yr) does. –  tomjedrz Aug 25 '09 at 17:30
    
Well noted, thanks! –  Andy Aug 25 '09 at 18:24
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I have personally done this before. In our student house we had 3 DSL connections that were then tied together. If you know your way around Linux, you can actually configure your routing so that it uses both your connections to access the Internet.

One easy way of sharing the connection is to get the Linux router to round-robin the internet connections through. There are other ways of load-balancing as well. The advantage is that when one link goes down, there is nothing much to do as the Linux router will fail-over as well.

This and more information can be found in LARTC.

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I have setup the Linksys RV042 multi WAN router for a few clients and it is very easy to setup, while being very powerful. You can do site-to-site hardware VPN's with it, and it will load balance for you as well as automagically failover between the two DSL's if one fails. Another plus is that they have come down in price very nicely, less than $200.

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I am also a big fan of the Peplink device. It has been working very well for my DSL + Cable setup for more than 2 years flawlessly.

http://www.peplink.com/balance/

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If you want to load balance and failover yourself, I saw this link a while ago. http://blog.taragana.com/index.php/archive/how-to-load-balancing-failover-with-dual-multi-wan-adsl-cable-connections-on-linux/

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Actually, with a load-balancing router, I think you would see a pretty big increase with Bittorrent transfers for a couple of reasons:

  1. ADSL connections are asyncronous. You could probably configure the router to send your uploads via one connection and downloads via the other. This would speed up both upload and download rates because ADSL is just one or the other, and not both at once. Trying to upload and download at the same time seriously degrades your bandwidth rate.

  2. Bittorrent connections are typically many connections in parallel, both uploading and downloading. The router could probably be configured to (or may do by default) balance these connections over both WAN links, effectively doubling your bandwidth.

Practically everything else on the other hand, wouldn't make much of a difference unless you had a lot of connections going at once.

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#1 is pretty wrong. ADSL can upload and download at the same time just fine. The asynchronous means that the up and down speeds are different, not that you can only do one at a time. The main problem you might see is very poor latency, but that can be resolved with a few simple router settings (cap your max upstream to 95% or so of your bandwidth) –  davr Aug 25 '09 at 21:28
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Load balancing inbound (downloads) is very easy, as you can do this with either a dedicated box (several of which are mentioned here) or software on xBSD/Linux. Load balancing outbound (uploads) is harder; to do it right requires cooperation from the provider of your IP block (usually your primary ISP, but it could be someone else who then tunnels your packets over your primary ISP). You can get some outbound benefit from tweaking DNS so that it has a very short TTL and alternates between the IPs on the different WANs -- this can speed up multiple simultaneous connections, but won't help with a single big connection (such as someone downloading a video from your server).

In theory you could send outbound packets over multiple WAN connections, but in reality your ISP's anti-spoofing will prevent this.

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I can't believe no-one has mentioned Vyatta here !

http://www.vyatta.com/

You can get the opensource version or get a business subscription (as well as a router rack). It'll do multi-wan and many other things.

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The article What can you do with a second ethernet port? gives a nice explanation of the various uses for multiple ethernet ports. The article is geared towards Linux users, so you will need to follow Windows-specific instructions if you decide to use any of the mentioned techniques.

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