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MVP
Posts: 3,009
Registered: ‎10-25-2011

Clients changing at different speed constantly

[ Edited ]

Hello everyone

I got a client which have notice that for example he is sitting on his desk which is really near an AP  and well he is connected at 300mbps and then it goes to 200, then 240 then 130 then 300 and so on(with full 5 bar signal)... and he was asking me why is doing that?  i actually never paid attention to that ever before...

Also there is another laptop which is a 1x1 abgn card  which is not that far from the AP.  it has well  3 bars windows signal and its connecting to 13mbs then it goes to 20mbs then 28mbs then it goes again to 13mbs... and so on...

I tried another laptop of him on the same place of the 1x1 abgn card which is better... of course because i think its a 2x2:2 card... the thing is that he is connecting to 300 for like 10 mins and then drops to 130mbps

 

The client is telling me that it didnt happen before... but i honestly think that he didnt notice it before(but i could be wrong)... and well he doesn tlike it.

You actuallly have to be in from of the AP to get a stable 300mbps and for example in the 1x1 card a stable 65mbps

 

It this a normal behavior?i ask this because like i said i never put attention to this before neither had a client asking me about that...

 

Config well

They are all APS 105

Band steering

airtime fairness

drop broadcast and multicast

encryptation is on AES

3 SSIDS(will reduce it to 2 when he gets the NPS)

Link aggregations everywhere

Clients are with the lastest driver i could find.

 

 

I honestly don thtink  its a config issue...

 

Neither there are many clients, on the AP, i was testing with just 3 clients

1 1x1  laptop

2  2x2:2 laptops.

 

Any idea what i could try to make it more stable? or  like i asked before is this normal? what does make this happen?

 

ideas are welcome :)

 

----------------------------------------------------
Product Manager - Aruba Networks
Alternetworks Corp
MVP
Posts: 3,009
Registered: ‎10-25-2011

Re: Clients changing at different speed constantly

Anyone?

 

----------------------------------------------------
Product Manager - Aruba Networks
Alternetworks Corp
Guru Elite
Posts: 21,260
Registered: ‎03-29-2007

Re: Clients changing at different speed constantly

The most definitive way to find out why is to do a packet capture while the client is doing that.  Clients will negotiate up or down based on their ability to successfully transmit a frame.  If there is more congestion/contention the client will negotiate down.

 

What I do not know is if what the Windows supplicant reflects as  the speed is truly accurate.  A packet capture will determine what is really going on.

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

MVP
Posts: 562
Registered: ‎11-28-2011

Re: Clients changing at different speed constantly

Windows doesn't reflect rates well in my experience. It's fairly ham-fisted with it.

 

I generally tell customers to ignore this and try something "real" (upload/download something) to get satisfaction.

 

Packet capture is a good idea. Maybe as another idea...

 

If the rest of the environment is as you describe, I generally suggest working with a "known good" client first. This is fairly quick.

 

For instance, I've carried my latest Atheros client machine (which runs like a train now I've tweaked a few settings) to every install in the last 3 years. In the last couple of scenarios like this, I park my laptop near the "trouble" client to demonsrate the AP/controller estate is ok. It's quick and dirty to prove things this way. Maybe try something similar with a device of yours you know is solid.

 

If it's not, go packet capturing maybe?

 

Kudos appreciated, but I'm not hunting! (ACMX 104)
MVP
Posts: 3,009
Registered: ‎10-25-2011

Re: Clients changing at different speed constantly

[ Edited ]

Yep that sounds like a good idea 

 

Guess i need to take somethings in mind when telling to the client

For example that wireless is a shared medium when wired is not.

 

there is a half of the throughput that need to take in consideration

 

So how much woudl you expect of speed if you are connected for example at 300Mbps?


Guess that would be maybe 300Mbps /2 = 150 Mbps

 

Then making the convertion  150Mbps/8 = 18.75MB/sec

 

That is what im expecting to see on the data file transfer if im doing a FTP transfer? or it would be less?

 

Take in mind that the test is done when im the only client connected to the network on a 5ghz band, really near the ap  with 40mhz channel and a client that support all that.

----------------------------------------------------
Product Manager - Aruba Networks
Alternetworks Corp
MVP
Posts: 562
Registered: ‎11-28-2011

Re: Clients changing at different speed constantly

Generally speaking, you're on the right lines.

 

However, the only thing I would say is that an 11n client consistently going over 18Mbyte is rare. The potential for this is generally in the hands of the client, in terms of adapter and antenna and driver quality (and OS to some extent).

 

For example, I've tuned my Atheros card as much as I can (it's a good adapter), and the most I can crank out of it is 18.1Mbyte. Iperf/Jperf and Chariot are good ways to test real throughput (on a couple of controlled machines).

 

Unless you want to spend a long long long long time analysing it, I'd say that anything over 15Mbyte (clean network and RF) in a basic test is a win.

 

Kudos appreciated, but I'm not hunting! (ACMX 104)
Guru Elite
Posts: 21,260
Registered: ‎03-29-2007

Re: Clients changing at different speed constantly

[ Edited ]

The Racking Monkey,

I would have to disagree with you on the throughput number above.  We have seen much higher throughput for clients, but that is not what Nightshade is talking about.  He is talking about the association rate, which is the speed that a client negotiates with an access point at that tim.

Let us remember that this thread is about finding out why the client reflect the association rate it does, NOT throughput. For that if  we simply grab a packet capture while the client is doing that, there is a column that will show the association rate and say if the client is reflecting what is truly in the air.

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

MVP
Posts: 562
Registered: ‎11-28-2011

Re: Clients changing at different speed constantly

Understood, but it looks to me like Nightshade has then started discussing actual throughput to me (Mbytes and FTP)?

 

Absolutely, when looking at association and throughput, focus should be in different places.

 

Nightshade will advise what his primary interest is I'm sure?

 

Regarding client potential, that's not what I'd say we see in the UK. Maybe it's different in the US (due to density or geography to some degree). It's very rare over here to see a client (for instance a HP laptop) get over 18Mbyte (when associated at 300Mbit). In the last 3 years, I think I've probably seen 4 or 5 good factory build corporate laptops. And I've seen countless (more than 50) perform less well than you'd ideally like.

 

Kudos appreciated, but I'm not hunting! (ACMX 104)
MVP
Posts: 3,009
Registered: ‎10-25-2011

Re: Clients changing at different speed constantly

My interest is both i actually want to know both  :)

If you want Collin i can open another tread for the other one.  I can also do a packet capture to check that :)

 

But i have seem in my test this.

 

When im putting the AP in bridge mode i get the actual trhougput im looking for and what i have calculated... i have seem on my machine 18.5  speed on my FTP server transfer speed.

 

I think the ranking monkey is right in the way that if i show this the client, he wont care what association speed he see on his laptop... he just thinking hey! why im connected to 108 instead of 300??? im getting lower speed...

But in the test on the AP on bridge mode im on 108mbs connected  i get 18.5mbs  which is the speed of 300mbs

 

Now if i put the AP in tunnel mode i get a total of 4MB/sec which is a way low...  This inspact is really high in the througput!

 

Now my scenario looks like this


CORE SWITCH----SWITCH----WC

 

The AP i plugged in the CORE SWITCH(this is just a testing lab) just because is poe and  is 1 giga.

 

Anyways all the uplinks are giga, i made sure everything was running on 1 giga...

I got no traffic going to the Switch  that i plugged my WC besides my wireless traffic.

 

Does the tunnel mode affect this much the throuput? i mean i know it has to tunnel to the  WC... and has to get back... but well  i kneow it affected in some way but not this mucc... its like 4 times slower.

If this is true  it is really important where you place the WC and also its really important to put in link aggregatioons...

 

Ill try  connecting it directly to the Coreswitch which it should a make  a differnce a think. its one less hop he has to do...  but well just got a controller 620 so i just got one giga port so well no link aggs...

 

Any commend about this?

----------------------------------------------------
Product Manager - Aruba Networks
Alternetworks Corp
MVP
Posts: 562
Registered: ‎11-28-2011

Re: Clients changing at different speed constantly

Ummmm. Very interesting.

 

So your bridge test is good? I think the important points to take away from that is...

 

1. The AP can perform fine RF wise.

2. The client seems ok.

3. Ignore the association rate reported. The OS or driver is probably mis-representing it. Don't worry about it.

 

Moving on...

 

Unless something in the controller config is affecting the throughput, you should get more than 4Mbps. That's wrong. So, I'd suggest you...

 

1. Check what version of code is on the 620. Upgrade it to the latest if possible.

2. If it's easy to move the controller to the core switch, yes do that.

3. Check the controller to switch port for errors and anomalies, plus speed and duplex. Consider fixing it at 1Gbps, as I've seen that help before. Depends on the switch.

4. Is the user ingress VLAN the same with the AP in tunnel mode as when in bridged? If not, try changing the tunnel AP VLAN to the same as the one in the bridge test. Any improvement?

5. Log a TAC case???

 

Good luck!

 

 

Kudos appreciated, but I'm not hunting! (ACMX 104)
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