Help with dual WAN load balancing (RT-N66U)

[Yuriman]

I recently moved into a more rural area and the fastest internet available here is DSL (FairPoint) @ 1.6/0.7. My household is relatively large, and it doesn't help that in the evenings there's a bottleneck at the fiber cable leaving town (according to the tech), causing speeds to approach that of dialup during peak hours. I decided to try having a second line installed and use the load balancing feature on my router to help in those times when we're all online and trying to stream music and watch YouTube videos, but I can't seem to get it working correctly.

My hardware:

RT-N66U w/Merlin 378.55
2x Netgear DM111PSP

Right now I'm using load balancing and have it set to 1:1, with routing rules disabled. Modem1 is on WAN, and modem2 is on LAN1. Both DSL lines work great independently in either the WAN port or LAN1, but when I enable dual WAN, pages fail to load 90% of the time and I can't fathom why. If I hit refresh repeatedly, eventually pages will load, and when they do, they load as quickly as they should. Speedtests (I have to refresh 20+ times before they load) show I'm getting the speed I should when the connection is finally established. It seems the outgoing connections just... aren't made? Maybe?

I've tried with both DSL modems in router+modem mode and with both as just modems with the Asus router providing the login info. I've switched the modems around too. Using either individually, things work great, but it's only when activating dual WAN that it doesn't.

I'm not sure what to do next. Maybe a different firmware version? Am I not understanding how dual WAN is supposed to work? I thought when establishing connections, the router would split attempts evenly between the two connections? Is this just the router misbehaving?

 

[Gryz]

Has anyone told you this setup would work ? Or did you just buy the equipment and assumed it would work in your scenario ?

The key thing to think about here is return traffic. Getting your packets out to the Internet is simple. But getting packets back from the Internet is not so easy.

Does your router connect to two ADSL modems from the same ISP ? Or two different ISPs ? Even if they would connect to the same ISP, it still wouldn't work. Does your router do NAT ? I assume it does.

Your router will have 2 WAN-interfaces (connected to your modems). Each interface will receive an IP-address from your provider via DHCP. Your devices at home all have a private IP-address (like 10.0.0.x, etc). When a packet from a device at your home leaves, goes to your router, and then gets sent out to the Internet, the router will change the source IP-address. This is NAT. The source IP-address will change based on which port the packet is being sent out. Because NAT will change the source IP-address to the IP-address of the outgoing WAN-port.

The means that your outgoing packets will sometimes have source IP-address X and sometimes Y. The webserver you are talking to will not know what X and Y are actually the same sender. It will see it as 2 garbled connections. And things will go horribly wrong.

Sometimes you might get lucky, and enough packets go out over the same ADSL link that packet with the same IP-address actually make it to the server. That's the 10% you will see that works. You were lucky.

If you want to make this work, you need to load-balance in a different way. You need to configure your router to load-balance flows of packets, not individual packets within each flow. Maybe your router has an option to do that.

Another way would be to configure your router with static routes to try and send half the traffic over interface X, and half the traffic over interface Y. If you understand the slash-notation for prefixes, then you might be able to set something up like:
ip route 0/1 interface X
ip route 1/1 interface Y

This would cause all traffic for destinations with an IP address where the first bit is a 0 to go out over interface X. And all destination where the first bit in the IP-address is a 1 go out over interface Y.

In older syntax this would be:
ip route 0.0.0.0 127.255.255.255 interface X
ip route 128.0.0.0 127.255.255.255 interface Y

I'm afraid that there will be more destination in the 128-224 range than in the 1-126 range. So your loadbalancing might be far from optimal.

Anyway, I hope you understand the problem a bit better now.

 

[Yuriman]

Thanks for the response. Various google searches on the topic have revealed many people with Asus routers simply plugging them in and it working. Example:

http://www.snbforums.com/threads/dual-wan-load-balance-and-3g-4g.16973/#post-125592

Hi,

It seems that there is not much people using dual wan load balance mode on routers? Atleast there is not much threads and talk about it.

I have used dual wan load balance with phone line DSL + 3G (with Huawei e3276) couple of days now with Merlin .40 fw and rt-66ac router. It seems pretty stable with primary 3:1 secondary configuration. Newer firmware has broken usb modem network scripts (Asus) so that's why I'm using .40 version.

I am really interested about this dual wan load balance because I sadly have phone line dsl available only about 7Mbit/s speed as only possible "fixed" internet connection to my apartment, so I would really prefer faster download speeds.

3G is new to me and I chose 3G over 4G because only 3G in my country is available with public ipv4 address.

There is some issues still in dual wan load balance, for example port forwarding/virtual server, VPN and so on remote functions do not work in dual wan load balance mode.

If there would be a possible way to for example "nail" remote services to primary WAN it would be great. But I really don't know what is the real issue behind this and is this easy way to make it work.

Also I have recognized that the usb modem puplic IP is pingable from WAN but the WAN port wan ip is not when the "wan ip pingable" option is not checked.

There was not many threads about Dual Wan Load Balance with or without usb modem and I know these are somewhat new options and most people do not prefer Load Balance, but instead Failover. But there are propably more people interested about this Load Balance and I'd like to gather to this thread peoples experiments and problems and ofcourse possible resolutions to the problems

Here's what the dual WAN page looks like:

https://www.asus.com/support/faq/1005714/

Yes, both DSL modems are to the same ISP. Yes, my router supports NAT. I've tried assigning individual IPs to specific WAN interfaces, but the problem persists.

I'm not sure how it's implemented in these routers, but I get the impression it works fine for many people. Even if I did know how it's implemented, there aren't many configuration options.

I already had the equipment laying around, and I can cancel the second DSL line within the first month and get my money back, but if this fails, I'll probably just set up two networks in the house and put half of the users/devices on each network to relieve some of the congestion at our end.

 

[JackMDS]

http://leonid.shevtsov.me/en/how-to-configure-dual-wan-on-asuswrt-routers

 

[mxnerd]

I wonder how PC network teaming is different from router load balancing/failover.

It seems PC network teaming will create a new MAC address but dual wan router will not, even on same ISP.

Here found TP-Link dual WAN router which let you configure how traffic flows

http://www.tp-link.com/en/faq-150.html

But seems ASUS RT-N66U has no such options. Don't know how it works.

 

[Gryz]

http://leonid.shevtsov.me/en/how-to-configure-dual-wan-on-asuswrt-routers

It seems that example is only using the 2nd adsl-line as backup when the first line fails. It does not do load-balancing, it seems. Also that page seems to be using standard Asus firmware, while the OP tries to get this working with Merling firmware.

People on the net telling us "it works fine" doesn't mean a thing. Especially when doing 3:1 load-balancing. Do you know if that guy actually checked if his traffic is really load-balanced ?

Does the router have more options besides "load-balancing" and "1:1" ? The trick to get this working is that all packets between a pair of computers (1 at your home, and 1 a webserver on the net) must go out over the same outgoing adsl-line. In router terminology this is called "per destination load-balancing". If you do "packet by packet load-balancing" it is 100% sure not to work with NAT. So, does the router have that option ? It should, or else it is bogus to sell the router advertising it can load-balance over 2 NAT connections.

 

[Yuriman]

I do know that when most of the people on the internet enable dual WAN with load balancing, they still have a working internet connection, and those that are using 3G/4G modems report data usage on them. So, enabling "load balancing", however it works, is directing some traffic through both connections, without breaking things entirely. When I enable it, I effectively don't have an internet connection.

Here's a dummy UI for the router:

http://event.asus.com/2012/nw/dummy_ui/en/index.html

^ That's an older firmware and it doesn't have the dual WAN page yet, but you can see what that page would have looked like from the image I posted, and just about everything else is there.

 

[Gryz]

That dummy UI, and the links you have provided are all using Asus's standard firmware. Yet you claim that your router is running Merlin software .....

On the Merlin pages (homepage and wiki) I do not see any options or info about load-balancing. When looking at the Asus documentation for the RT-N66U, I don't see anything about load-balancing either.

Edit: oh, what. Merlin is based on Asus open source software. But the Merlin developer didn't bother making his software distinguishable from the standard firmware. Ugh.

If I were you, I'd drop an email (or a twitter message) to the guy who made Merlin. If one guys has developed this software on his own, nobody else in the world is gonna be able to help you if there are bugs or unfinished features.

 

[mxnerd]

IIRC, I configured a Linksys Cisco dual WAN router like TP-Link, it will let you specify which protocol goes through which WAN port. If a websites consisted of both http & https docs, it will break. So you might have to define routing rules.

and actually it will not bond the link unless a download is multi-threaded (using a multi-threaded downloader) according to Nitra.
http://www.dslreports.com/forum/r29298875-DUAL-WAN-RT-N66U-RMerlin-Firmware

ZyWALL's dual WAN router has 3 options
1. Weighted Round Robin
2. The Least Load First
3. Spillover

http://www.smallnetbuilder.com/lanwan/lanwan-howto/32577-how-to-set-up-your-dual-wan-router

Also don't know what type of load balancing ASUS implemented for RT-N66U

===

None of dual wan routers can do bonding if not done by ISP side.

http://www.tomshardware.com/answers/id-2522411/require-assistance-wan-isp-shaw-telus-ac87u-asus.html

http://superuser.com/questions/660798/merging-two-incoming-broadband-lines-for-faster-internet


===

Your DSL provider must support MLPPP protocol to give you a bigger pipe.

http://forums.anandtech.com/showthread.php?t=2316689

 

[Yuriman]

That dummy UI, and the links you have provided are all using Asus's standard firmware. Yet you claim that your router is running Merlin software .....

On the Merlin pages (homepage and wiki) I do not see any options or info about load-balancing. When looking at the Asus documentation for the RT-N66U, I don't see anything about load-balancing either.

Edit: oh, what. Merlin is based on Asus open source software. But the Merlin developer didn't bother making his software distinguishable from the standard firmware. Ugh.

If I were you, I'd drop an email (or a twitter message) to the guy who made Merlin. If one guys has developed this software on his own, nobody else in the world is gonna be able to help you if there are bugs or unfinished features.

I did drop a post on SNB as well, but Merlin has said repeatedly that the load balancing code is straight from Asus and that he has not modified it in any way. It's available on the stock firmware, the dummy UI that you see is simply for a slightly older firmware, it's the best I could do. Take a look at the image I've linked above for the missing page.

 

[Gryz]

In that case you should ask Asus. If it is supposed to "just work", but it isn't, and there are no other config options to change the type of load-balancing, then we can discuss about theoretical issues for years here. It won't solve the problem.

Or you should try the firmware from Asus. See if that works. I bet they won't try to help you if you run 3rd party firmware.

 

[Yuriman]

I'll try giving them a call, but I have a small update for this thread:

Earlier I moved back to stock Asus firmware, just to see, and the behavior is the same. HOWEVER, I had not realized that my mobile devices (iPads, android phones) have no issues on the network with load balancing enabled, it's only the Windows PCs. I haven't tried my Chromebook yet., but on the Windows PCs it doesn't matter what browser I use, or what program is trying to access the web, and it's all of the PCs, but all of my non-Windows mobile devices work fine. Is there any reason why Windows 10 might not work out-of-the-box with this?

 

[einstein11]

hi, just wanted to know if there have been any updates to the dual wan load balancing situation with merlin firmware, trying to get it going at the moment (2 modems with different isps). wondering if it is worth the trouble or if i should just create 2 networks (1 lan and one wifi).doesnt seem to be much online from anyone that has actually got this up and running stable and efficient.






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