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gius64
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Nv2 - pfifo: low speed, sfq: high speed. Why?

Fri Mar 28, 2014 3:00 am

Hello everyone,
I had a really strange problem. I solved it, but I want to share this experience to better understand it.

I have a bridged network with a gateway on Optical Fiber internet connection and some wireless APs to allow users to connect using their CPE.

I used 5GHz-A and 802.11 or nstreme and I want to switch to 5GHz-N with nv2 as my users grown up.

On the gateway I have user manager to limit my users.

When I switched to nv2 on one of my AP to test it I had a speed drop.
If an user had 30Mbps stable before, with nv2 is super unstable and only 10-14Mbps.
Users with 10Mbps were stable before, with nv2 unstable and only 5-6Mbps.

This is an user with nv2 that had stable 30Mbps in nstreme:
limit_pfifo.jpg
The strange thing is that if i remove the limit, without changing anything else, this is the speed:
no_limit_.jpg
Very strange! :shock:
Searching on the forum i found http://forum.mikrotik.com/viewtopic.php?f=13&t=77052.

I set this on the AP:
/queue type set default-small kind=sfq
And this is the result: perfect 30Mbps limitation and stable :D
limit_sfq.jpg
Before I had pfifo queue (default-small default).
Why, on the same AP, same users, same frequency, but different protocol, pfifo performed well with the older protocols and not with nv2?
Why is sfq better? Is there any side effect using sfq?
I also tried red and pcq and the results are the same: good as sfq.
Only using pfifo and mq pfifo I have this issue.

Can you please explain me why this happens?
On the gateway I'm using pfifo on the WAN as queue type and I'm not having any issue.
Do you think changing it to sfq, red, or mq pfifo can help?

I read about queues on the wiki but I can't understand why I'm facing this.

Thank you
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rextended
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Fri Mar 28, 2014 7:23 pm

Hello everyone,
I had a really strange problem. I solved it, but I want to share this experience to better understand it.

I have a bridged network with a gateway on Optical Fiber internet connection and some wireless APs to allow users to connect using their CPE.

I used 5GHz-A and 802.11 or nstreme and I want to switch to 5GHz-N with nv2 as my users grown up.

On the gateway I have user manager to limit my users.

When I switched to nv2 on one of my AP to test it I had a speed drop.
If an user had 30Mbps stable before, with nv2 is super unstable and only 10-14Mbps.
Users with 10Mbps were stable before, with nv2 unstable and only 5-6Mbps.

This is an user with nv2 that had stable 30Mbps in nstreme:
limit_pfifo.jpg
The strange thing is that if i remove the limit, without changing anything else, this is the speed:
no_limit_.jpg
Very strange! :shock:
Searching on the forum i found http://forum.mikrotik.com/viewtopic.php?f=13&t=77052.

I set this on the AP:
/queue type set default-small kind=sfq
And this is the result: perfect 30Mbps limitation and stable :D
limit_sfq.jpg
Before I had pfifo queue (default-small default).
Why, on the same AP, same users, same frequency, but different protocol, pfifo performed well with the older protocols and not with nv2?
Why is sfq better? Is there any side effect using sfq?
I also tried red and pcq and the results are the same: good as sfq.
Only using pfifo and mq pfifo I have this issue.

Can you please explain me why this happens?
On the gateway I'm using pfifo on the WAN as queue type and I'm not having any issue.
Do you think changing it to sfq, red, or mq pfifo can help?

I read about queues on the wiki but I can't understand why I'm facing this.

Thank you
share info is good!

+2
I'm Italian, not English. Sorry for my imperfect grammar.
 
gius64
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Fri Mar 28, 2014 8:09 pm

Thank you! I hope to understand why it happens :lol:
 
marcin21
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Fri Mar 28, 2014 10:01 pm

+1
You shed a light on my network. finally it solved my problem with pppoe based network queues.
 
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Sat Mar 29, 2014 12:37 am

Please, do not simply write +1, add Karma to the author of this post, if you want thank he.
I'm Italian, not English. Sorry for my imperfect grammar.
 
gius64
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Sat Mar 29, 2014 4:16 am

Thank you guys, would be great if we can understand why it happens...
Any tip about queue type on the main gateway?
 
gius64
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Fri Jun 20, 2014 2:36 pm

Hello everyone,
do you have any news about why it does like this?
I would like to understand if there are side effects...

MikroTik? Anyone?
[Ticket#2014062166000185]

Thank you
 
gius64
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Wed Jun 25, 2014 3:15 pm

This is the answer from MikroTik:
For different applications different type is best for long links
PFIFO 200 it best for other RED would improve latency and speed.

RED with default settings but you can tune it changing values.

SFQ is default for for hardware wireless and it works good in most cases but in
specific usages / applications is best to change different type.
 
marcin21
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Wed Jun 25, 2014 5:56 pm

what an answer!

bla bla try what suits You the best. tune up or not if You wish.
frankly speaking we don't know why it does make such enormous difference.
if it is so let it be so.
m....k

cool is that it solved my problem i've been strugling for years. to have right transfer queue limit by mtik.
and solution was so simple.
 
gius64
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Wed Jun 25, 2014 6:06 pm

I don't know why it makes such a big difference, and I don't know if RED is best than SFQ and in what cases...
I read theory on the wiki but it shouldn't make such a big difference.

It's a point for them to show how good nv2 is, but i never found an official guide from MikroTik where they talk about queues and optimization you can do on them over a wireless network in ptmp.

I think that some example from who is behind RouterOS would be great.
 
Zorro
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Tue Sep 23, 2014 2:24 pm

RED interesting, but unusable in archaic/notorious shape/state we're see it in RouterOS.
both lacks of self-tuning and immunity for DoS with spoofing.
RRED in my opinion is MUCH better. plus as with all AQM queus, you resolve congestion issues.
but isn't such plans for ROS, aired, sadly. but i left in one of my "feture requests" mention of it.
 
ste
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Re: Nv2 - pfifo: low speed, sfq: high speed. Why?

Tue Sep 23, 2014 3:08 pm

what an answer!

bla bla try what suits You the best. tune up or not if You wish.
frankly speaking we don't know why it does make such enormous difference.
if it is so let it be so.
m....k

cool is that it solved my problem i've been strugling for years. to have right transfer queue limit by mtik.
and solution was so simple.
We had the same thing the other way round in the past. sfq limited speed and pfifo was better.
So dont trust your experience.

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