Bandwidth distribution challenge

[Hermes14]

Greetings,

Router: RT-AC66R
Firmware: 3.0.0.4.374.40_0 (Merlin Build)
OS: Vista (directly connected to the router via ethernet)

Challenge: Over the past few months my bandwidth distribution has been uneven; all bandwidth goes to one task at a time.

Scenario:
Total bandwidth speed is 2mbps,
When I download a large file it takes up the entire 2mbs,
When I open another task (download or webpage), it either fails to load or takes forever. The download task is still using the entire 2mbs.

The problem is system-wide: If I open a task on the same machine as the original task, , it either fails to load or takes forever. If I open a task on another machine in the network, it either fails to load or takes forever.

Of course, what *should* happen is that, all else being equal, a second task on the network should take half the bandwidth. So a second download should eventually even out with the first one, each at 1mbps.

I don't know if the following is relevant: My ISP provides 10mbps, but after a few seconds of continuous stream at the maximum available speed it throttles back to 2mbps. During the first few seconds of a longer download, I can open other webpages etc. easily. As a test, I started two downloads nearly simultaneously: Watching the download meters you could see the available bandwidth switching between the two tasks.

Another thing: I've noticed that torrent clients tend to hog the entire bandwidth stream as well. Could that be related?

Again: Things did not always behave this way; bandwidth distribution used to be even. Is there something wrong in the router setting? How can I diagnose and solve this?

Thanks in advance for your help!

 

[Hawk]

First step would be to bypass router and directly connect ISP modem and router combo and see if it has same issue.

 

[Zirescu]

Could try updating to a more current version of Merlin as well.

 

[Nullity]

...
Of course, what *should* happen is that, all else being equal, a second task on the network should take half the bandwidth. So a second download should eventually even out with the first one, each at 1mbps.

Incorrect assumption. 2 perfectly identical connections may split approximately even, but in the real world this is untrue. This fact is the basis of decades of research into fair queuing.

I don't know if the following is relevant: My ISP provides 10mbps, but after a few seconds of continuous stream at the maximum available speed it throttles back to 2mbps. During the first few seconds of a longer download, I can open other webpages etc. easily. As a test, I started two downloads nearly simultaneously: Watching the download meters you could see the available bandwidth switching between the two tasks.

Another thing: I've noticed that torrent clients tend to hog the entire bandwidth stream as well. Could that be related?

Again: Things did not always behave this way; bandwidth distribution used to be even. Is there something wrong in the router setting? How can I diagnose and solve this?

Thanks in advance for your help!

Are you using merlin's firmware?

If so, it includes a fair queuing algorithm called ESFQ (an "enhanced" Stochastic Fair Queuing algo). Fair queuing is usually concerned with fairness among connections (or "flow") which may help improve your problem, but may not achieve exactly what you want.

FreeBSD's dummynet (or pfSense's "limiters") offers the option to dynamically share bandwidth among hosts/IPs. So, 2 hosts get 1Mbit each, 4 hosts get 0.5Mbit each. Each host can also use all the bandwidth if it is available. pfSense example: https://forum.pfsense.org/index.php?topic=63531.0


A quick note; your goal and the topics it involves are complex (like anything, I guess). Your problem may need a more active approach, like manually separating each host or port or subnet into different limits.

 

[Hermes14]

First step would be to bypass router and directly connect ISP modem and router combo and see if it has same issue.

The ISP-modem and router combo is already directly connected to the main machine via hardwire. Your suggestion inspired me to disconnect the router and plug the modem into the machine directly (perhaps that's what you meant?). Running two downloads at once appears to gradually balance out. That increases the likelihood that the problem is in the router.

Thank you, Hawk.

 

[Hermes14]

Incorrect assumption. 2 perfectly identical connections may split approximately even, but in the real world this is untrue. This fact is the basis of decades of research into fair queuing.

Sure, that's why I added the caveat, "all else being equal"; rarely so in the real world, but an ideal for purposes of the scenario.

Are you using merlin's firmware?

Firmware: 3.0.0.4.374.40_0 (Merlin Build)

If so, it includes a fair queuing algorithm called ESFQ (an "enhanced" Stochastic Fair Queuing algo). Fair queuing is usually concerned with fairness among connections (or "flow") which may help improve your problem, but may not achieve exactly what you want.

FreeBSD's dummynet (or pfSense's "limiters") offers the option to dynamically share bandwidth among hosts/IPs. So, 2 hosts get 1Mbit each, 4 hosts get 0.5Mbit each. Each host can also use all the bandwidth if it is available. pfSense example: https://forum.pfsense.org/index.php?topic=63531.0


A quick note; your goal and the topics it involves are complex (like anything, I guess). Your problem may need a more active approach, like manually separating each host or port or subnet into different limits.

Thank you, Nullity. I'll study this more. OTOH, this is a recent problem. For most of the time I've owned the router it hasn't been an issue. So I'm hoping it's not *too* complex -)

 

[Hermes14]

If so, it includes a fair queuing algorithm called ESFQ (an "enhanced" Stochastic Fair Queuing algo). Fair queuing is usually concerned with fairness among connections (or "flow") which may help improve your problem, but may not achieve exactly what you want.

Are there parameter settings in the firmware for this algorithm? Where are they? Does the QoS page handle this?

 

[Hermes14]

Could try updating to a more current version of Merlin as well.

I'll plan to update soon. I found these instructions:

http://blog.usro.net/how-to-install-asus-wrt-merlin-router-firmware/

Is this sufficient, or is there anything else I should know before updating?

Thank you, Zirescu.

 

[Nullity]

Sure, that's why I added the caveat, "all else being equal"; rarely so in the real world, but an ideal for purposes of the scenario.

The real problem is relying on outside conditions to be perfect to achieve what you want.

Are there parameter settings in the firmware for this algorithm? Where are they? Does the QoS page handle this?

Sadly, there is no GUI configuration. Even more sadly, you would need to use the rather awful "tc" command-line program.

Hopefully there is another way that are open to, like tomato firmware, but otherwise you would need to do some non-trivial things like buying new hardware or installing (and learning) pfSense on to a PC and using it as your router.

 

[Zirescu]

I'll plan to update soon. I found these instructions:

http://blog.usro.net/how-to-install-asus-wrt-merlin-router-firmware/

Is this sufficient, or is there anything else I should know before updating?

Thank you, Zirescu.

Those instructions aren't quite what I'd use. Official Merlin site is: http://asuswrt.lostrealm.ca

Your version of Merlin is over two years old and I suspect you're going to have to do incremental updates between the major versions. Official downloads are under the RT-AC66U folder here: https://www.mediafire.com/folder/bkfq2a6aebq68/Asuswrt-Merlin

You'll probably want to download all of the following firmware versions first and extract them and then perform the upgrades in order:
1. Upgrade to: 376.49_5
2. Perform a factory default reset under Administration->Restore/Save/Upload Setting
3. Than upgrade to: 378.56_2
1. Upgrade to: 380.57
2. Perform a factory default reset.
3. Setup the router manually, don't restore from a saved config.
4. If you're going to use the same SSID that you had previously, delete the stored settings from all the clients and than add them back in again. (Might be better to use a new SSID).


Edits after Merlins comment about not needing to do incremental updates on AC66U.
Cheers.

 

[RMerlin]

I suspect you're going to have to do incremental updates between the major versions.

Not necessary with the RT-AC66U.

 

[Hermes14]

1. Upgrade to: 380.57
2. Perform a factory default reset.
3. Setup the router manually, don't restore from a saved config.
4. If you're going to use the same SSID that you had previously, delete the stored settings from all the clients and than add them back in again. (Might be better to use a new SSID).

Thank you, Zirescu; and thank you, Merlin, for the annotation.

1. Everything is updated, and with new SSID's.

2. QoS settings:

Enable QoS : ON
QoS Type: Traditional QoS
Bandwidth Setting: Manual

[Automatic doesn't work; selecting Automatic and doing Apply takes me back to Manual]

[I just noticed Bandwidth Limiter: I would like to learn how to use this!]

3. At first appearances, QoS ON seems to help, but overall bandwidth distribution is still not as balanced as I remember it... I'll watch it for the next few hours or so and see what happens.

Thank you all for your help!

 

[Nullity]

The easiest method is to simply limit the throughput at the client when you are downloading so that there is excess bandwidth available to anything else that needs it. This same method can be used at the router, but it is much more complex and less reliable.



A good introduction to the fundamental aspects of QoS can be found here: http://www.linksysinfo.org/index.php?threads/qos-tutorial.68795/