Reply
Ubiquiti Employee
Posts: 6,613
Registered: ‎05-13-2009
Kudos: 2086
Solutions: 205

Re: airMax - aggregation - priority

This does not jive with my results so far.

Does am pri affect link conditions?


No, it doesn't affect link conditions. AM priority does change time slot size given for that station. If it's PtP link, it shouldn't affect at all, as it's only one device to which AP is communicating.

-Edmundas
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

No, it doesn't affect link conditions. AM priority does change time slot size given for that station. If it's PtP link, it shouldn't affect at all, as it's only one device to which AP is communicating.
-Edmundas

So, to be clear, you're saying that am does not adjust for or have any effect on aggregation at all, and vise verse...correct?
So if you have an AP with 50 subs and all have agg set to max, that they will use that setting regardless of size of time slot given?
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Ubiquiti Employee
Posts: 6,613
Registered: ‎05-13-2009
Kudos: 2086
Solutions: 205

Re: airMax - aggregation - priority

So, to be clear, you're saying that am does not adjust for or have any effect on aggregation at all, and vise verse...correct?

So if you have an AP with 50 subs and all have agg set to max, that they will use that setting regardless of size of time slot given?


Aggregate should be fit in 4ms. So not depending what maximum setting you have specified in WEB UI, it still be be limited to these 4ms. This time directly depends from channel width and link conditions, but not airMAX priority.

-Edmundas
SuperUser
Posts: 21,761
Registered: ‎11-20-2011
Kudos: 7925
Solutions: 233

Re: airMax - aggregation - priority

Aggregate should be fit in 4ms. So not depending what maximum setting you have specified in WEB UI, it still be be limited to these 4ms. This time directly depends from channel width and link conditions, but not airMAX priority.

-Edmundas



^^^^^^^^ We need a place to sticky stuff like this.


isp builder | linux sorcerer | datacenter automation conjurer | blog: blog.engineered.online
link to our slack channel on the blog
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

Aggregate should be fit in 4ms. So not depending what maximum setting you have specified in WEB UI, it still be be limited to these 4ms. This time directly depends from channel width and link conditions, but not airMAX priority.

-Edmundas


What does the 4ms refer to if it is not based on am pri? Are you saying that the smallest time slice given to a sta regardless of AP load is 4ms @ 40mhz chw? And 3 @ 30; 2 @ 20; 1 @ 10; ? @ 5?

And how does wlan latency affect the am slot and aggregation? I see picture perfect links @ .2miles hit 3ms wlan latency. Is it taken into account so that the aggregate frame buffered and ready to fly has enough time to get to its destination...is that frame dropped...is that slot missed?

And if the agg settings in the web ui are max settings, why would there be a performance improvement by lowering it if it's automatically lowered based on link performance anyway? That would make it pretty silly to have anything other than enable/disable wouldn't it? From your description, it should be set to max (not 50000) and forgotten since the system takes it from there anyway.

Your description is the opposite of what Matt said, and what I've observed.
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

What does the 4ms refer to if it is not based on am pri? Are you saying that the smallest time slice given to a sta regardless of AP load is 4ms @ 40mhz chw? And 3 @ 30; 2 @ 20; 1 @ 10; ? @ 5?

And how does wlan latency affect the am slot and aggregation? I see picture perfect links @ .2miles hit 3ms wlan latency. Is it taken into account so that the aggregate frame buffered and ready to fly has enough time to get to its destination...is that frame dropped...is that slot missed?

And if the agg settings in the web ui are max settings, why would there be a performance improvement by lowering it if it's automatically lowered based on link performance anyway? That would make it pretty silly to have anything other than enable/disable wouldn't it? From your description, it should be set to max (not 50000) and forgotten since the system takes it from there anyway.

Your description is the opposite of what Matt said, and what I've observed.


I need this information to fine tune things so I can get as much performance as possible until you fix the firmware.
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

I need this information to fine tune things so I can get as much performance as possible until you fix the firmware.


You guys stumped on these questions or what?
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Emerging Member
Posts: 107
Registered: ‎11-08-2011
Kudos: 76
Solutions: 1

Re: airMax - aggregation - priority

Does airmax priority effect what a customer gets as far as bandwidth? What is everyone else setting their customers to?
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

Hello...Matt...Edmundas...Sriram
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Deleted Account
Posts: 0

Re: airMax - aggregation - priority

Hello...Matt...Edmundas...Sriram


Edmundas and I were both travelling yesterday... please be patient with responses, no need to bump a few times within 24 hours.

Did my response make sense to you?

I'm not sure about Edmundas' response, maybe he's talking about airSync... I'll let him respond when he's back.

-Matt
Regular Member
Posts: 466
Registered: ‎07-09-2008
Kudos: 184
Solutions: 2

Re: airMax - aggregation - priority

I don't know how it works with ubnt QOS, but aggregation is an old tech I've used for close to a decade with Alvarion VL gear and Mikrotik nstreme.

In interference conditions, a smaller aggregation is better performing since a small wireless packet is less statistically likely to get cross-mojinated with an interference signal because it exists for a shorter period of time. The original canopy gained it's strength from this as it's radio packets were actually smaller than the ethernet packets.

In ideal situations, you can get more packets-per-second with aggregation. Most IP/ethernet packets are not full sized and aren't efficient to send one at a time. It used to be that you could "fill" a 54mb link wireless link or slow down a 100mb cisco router with a few mb of voip or p2p or ddos simply because of the small packets being used. Things like MT nstreme and Alvarion VL addressed this problem before aggregation became more common and standard.

Reducing latency by decreasing aggregation size will reduce total available bandwidth, but I suspect most ubnt airmax users aren't currently using the full capacity of most of their links. (I am at capacity on a couple of links, but have many that are only gently used)
Jason Philbrook
Member
Posts: 155
Registered: ‎02-16-2011
Kudos: 23

Re: airMax - aggregation - priority

I've been fooling with aggregation settings all morning and was able to increase bandwidth across my entire network...up to double the previous bandwidth per device by NOT USING THE DEFAULT 32/50000!

The answer to the op would be important information for Ubiquiti to share with us!!!

I'm dying here...what setting did you use???
Ubiquiti Employee
Posts: 6,613
Registered: ‎05-13-2009
Kudos: 2086
Solutions: 205

Re: airMax - aggregation - priority

What does the 4ms refer to if it is not based on am pri? Are you saying that the smallest time slice given to a sta regardless of AP load is 4ms @ 40mhz chw? And 3 @ 30; 2 @ 20; 1 @ 10; ? @ 5?

And how does wlan latency affect the am slot and aggregation? I see picture perfect links @ .2miles hit 3ms wlan latency. Is it taken into account so that the aggregate frame buffered and ready to fly has enough time to get to its destination...is that frame dropped...is that slot missed?

And if the agg settings in the web ui are max settings, why would there be a performance improvement by lowering it if it's automatically lowered based on link performance anyway? That would make it pretty silly to have anything other than enable/disable wouldn't it? From your description, it should be set to max (not 50000) and forgotten since the system takes it from there anyway.

Your description is the opposite of what Matt said, and what I've observed.


Maximum aggregate value in WEB UI does allow you to decrease aggregate size lower than wireless driver will use according link conditions it thinks it good to use. So in worse link condition, smaller packets are more efficiently delivered and your test results it clearly shows it.

-Edmundas
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

I don't know how it works with ubnt QOS, but aggregation is an old tech I've used for close to a decade with Alvarion VL gear and Mikrotik nstreme.

In interference conditions, a smaller aggregation is better performing since a small wireless packet is less statistically likely to get cross-mojinated with an interference signal because it exists for a shorter period of time. The original canopy gained it's strength from this as it's radio packets were actually smaller than the ethernet packets.

In ideal situations, you can get more packets-per-second with aggregation. Most IP/ethernet packets are not full sized and aren't efficient to send one at a time. It used to be that you could "fill" a 54mb link wireless link or slow down a 100mb cisco router with a few mb of voip or p2p or ddos simply because of the small packets being used. Things like MT nstreme and Alvarion VL addressed this problem before aggregation became more common and standard.

Reducing latency by decreasing aggregation size will reduce total available bandwidth, but I suspect most ubnt airmax users aren't currently using the full capacity of most of their links. (I am at capacity on a couple of links, but have many that are only gently used)


It isn't ubnt QOS, it's the interaction with ubnt polling I'm questioning. I understand how agg is supposed to work in a normal system, but figured there must be something different since the default value of 50000 makes no sense. I have always assumed there was a link to airMax.

Since there has been issues with performance in recent fw versions, I decided to fool with the agg settings. My results made me start this thread because if agg works as it always has in other systems, there may come a point when agg and airMax are at odds with each other if am is not factoring in the agg settings. So in depth information is needed in order to fine tune the network without crippling one or the other.

And when Edmundas said that any agg setting works because there would always be 4ms...that confuses me a little since the timeslots are dynamic based on active users and priority, and that implies a min 4ms delay per active station. 50 active stations means a min of 200ms latency...under which priority? And how does wlan latency effect the time slot if there is only 4ms to pass data? Although that would explain the massive drop in throughput under less than optimal link conditions.

There is a lot of detail missing that is required in order to properly engineer a network. And some things are just plain not making much sense.
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

Maximum aggregate value in WEB UI does allow you to decrease aggregate size lower than wireless driver will use according link conditions it thinks it good to use. So in worse link condition, smaller packets are more efficiently delivered and your test results it clearly shows it.

-Edmundas



A true statement if you disregard what I said about doubling throughput on some by increasing to 65000 on links only getting 88% CCQ & 65%AMQ. If link quality is truly playing a roll, increasing to max should have zero effect because the drivers will still use a smaller value...unless it isn't working correctly.

And please answer my question concerning your reference to 4ms...see above post too.
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

I'm dying here...what setting did you use???


I posted it.
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Ubiquiti Employee
Posts: 6,613
Registered: ‎05-13-2009
Kudos: 2086
Solutions: 205

Re: airMax - aggregation - priority

A true statement if you disregard what I said about doubling throughput on some by increasing to 65000 on links only getting 88% CCQ & 65%AMQ. If link quality is truly playing a roll, increasing to max should have zero effect because the drivers will still use a smaller value...unless it isn't working correctly.

And please answer my question concerning your reference to 4ms...see above post too.


Yes, increasing aggregation size actually hard to believe that could make any difference due to the limitation inside wireless driver. Smaller aggregation size would make sense.

4ms is a time needed to process aggregate (how driver determines aggregate size) in wireless driver, it's not a airtime given for station or a created latency what you could see with various test tools (i.e. ping). Also I don't think that I could give you more detailed explanation, as I'm not the wireless driver developer and don't know how exactly everything is processed there inside.

-Edmundas
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

Edmundas and I were both travelling yesterday... please be patient with responses, no need to bump a few times within 24 hours.

Did my response make sense to you?

I'm not sure about Edmundas' response, maybe he's talking about airSync... I'll let him respond when he's back.

-Matt


Yes, there is a need. There have been performance issues for well over a year. These questions are about me giving up on you guys getting them fixed and resorting to tweaking every knob to wring out every drop of performance I can get. I need questions answered since it isn't in the manual. And since my network, among others obviously, has suffered for this past year due to these issues, I think it's reasonable to expect you guys to be forthcoming with detailed answers in a timely manor during business hours.

It was my understanding that Ubiquiti touts having a couple of engineers monitoring the forums at all times. So I wouldn't expect to need to wait for you or Edmundas...and I wouldn't expect both of you to be unreachable for an entire day--because evidently you are actually the only two monitoring the forums.

So forgive me if I don't want to wait another year to get my network up to snuff without just replacing all of my gear.
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

Yes, increasing aggregation size actually hard to believe that could make any difference due to the limitation inside wireless driver. Smaller aggregation size would make sense.

4ms is a time needed to process aggregate (how driver determines aggregate size) in wireless driver, it's not a airtime given for station or a created latency what you could see with various test tools (i.e. ping). Also I don't think that I could give you more detailed explanation, as I'm not the wireless driver developer and don't know how exactly everything is processed there inside.

-Edmundas


Why would there be a driver limitation stopping the legitimate use of 65000? Is that specific to the ubi drivers?

Are you sure that you don't mean 4us? 4ms is a huge amount of time in kernel space.
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Established Member
Posts: 1,005
Registered: ‎09-29-2009
Kudos: 66
Solutions: 1

Re: airMax - aggregation - priority

Aggregate should be fit in 4ms. So not depending what maximum setting you have specified in WEB UI, it still be be limited to these 4ms. This time directly depends from channel width and link conditions, but not airMAX priority.

-Edmundas


What do you mean by channel width? Give me an example comparing 5mhz and 20mhz.
Rural Crossing
Internet & Community Networks
Northeast Indiana; Northwest Ohio; Lower Michigan
Reply