Wireless Access

I've been receiving complaints that laptops are losing wifi connectivity briefly.  It lasts about 10 seconds and the user is usually aware of the issue because Outlook will disconnect from Exchange and they'll be logged out of our internal messaging client.   I don't see anything logged on the client side and Airwaves isn't showing anything of concern.  Sometimes I see a client associate with different APs throughout the day in the same area, and for whatever reason they're switching bands each time.  I'm not sure if this is causing the loss of connectivity or if it's something else.  I've tried upgrading wireless drivers and for some this seems to help, but I'm not convinced there isn't something on the Aruba side that needs to be tweaked.  Any thoughts on how to troubleshoot this issues?

1.  What version of arubaOS?

2.  What clients are these?

3.  Do clients share a layer2 network with wired clients?

4.  How many clients on the WLAN?

5.  Are you using Broadcast Filter all, to filter downstream broadcasts?

 

1. We're on 5 code, and are upgrading to the latest 6 code very soon.
2. Mixture of Dell laptops.
3. Wireless clients are segmented from wired clients.
4. 350 - 400 in a single L2 domain
5. No.  I'm not very familar with the feature so I've been afraid to enable it.  I don't know what sort of impact this would have on client connectivity.

Broadcast filtering at the Virtual AP level stops broadcasts and improves performance.

 

Anything that depends on multicast, will not work when you enable this.  Fortunately if you have active directory, nothing relies on multicast.

 

Won't disabling broadcasts affect connectivity to other clients in the same broadcast domain?

No.  Clients usually find each other via unicast.

 

I think I will start with enabling convert broadcasts to unicasts.  However, we still use netbios to some extent, and I need to know how enabling this setting will affect netbios traffic.  Again, I don't want to drop all BCMC traffic, I just want to convert broadcasts to unicast for now.

What do you use netbios for?  Most users enable "Brodcast Filter All" and "Broadcast Filter ARP" and enjoy better performance and very few drawbacks.

 

I'm not entirely sure.  I've been informed by a few different groups that netbios is still in use.  I'll have to get some more information from the other departments before knowing if I can turn this feature on without any disruption.

Any thoughts on why clients would roam to different APs during the day and switch bands? As a bandaid, I've had to ask clients to disconnect their wifi and re-enable, as they tend to reconnect at 5GHz instead of the 2.4GHz that they were on.  (We have band steering enabled, with 5GHz being the preference.)

That is because:

 

- RF changes throughout the day

- Different Clients have different algorithms for deciding what access points and what bands they connect to.

- We can only attempt to influence them.  Ultimately the client makes the decision.

 

 

Part of the problem is that I have a client consistently disconnecting from an AP on 5GHz that's very close, to an AP on the floor above at 2.4GHz.  He has issues with speed and signal strength when this happens.  Any suggestions for influencing a client to only connect to APs on the same floor?

The most important thing when you have a dual-band deployment is that you have enough density to serve the A band at minimum.  In a typical office environment you are looking for an access point every 60 feet.  If you do not, you will have those types of issues.

 

What is your density?

Roughly 35 connections per floor.  A floor is roughly 10,000 sq feet and has 5 APs.

Not bad.  6.1.x will give you additional tools to monitor and manage your network.  You should upgrade.  

Upgrade is scheduled for tomorrow.  Hoping that some good comes out of it.

After the upgrade, we're still seeing random disconnects with users.  It's happened to me at least 2 times today.  In fact, it happened to me and a colleague at the same time.  We were both connected to the same AP.  I've also heard from another user whose application has lost connectivity 4 times today which is about normal for her.

 

Any ideas on why we're dropping randomly or what I can to do track the problem down?  Our wifi is catchin' a bad rap around here because of this.

On the Dashboard, screen, you should be able to see if any access points have interference, have low noise, etc.  Start there.

 

Too late to look at the dash, but AirWave shows the following stats at around the time we got disconnected:

 

5GHz

Noise: -90dBm

Interference: 3%

Busy: 8%

 

2.4GHz

Noise: -93dBm

Interference: 10%

Busy: 84%

 

Both me and my colleague were on 5GHz at the time.  I noticed another client drop from 2.4GHz at the same time which is why I included metrics for that radio as well.

 

Is there any logging that I can enable that would be helpful?  Every time we have someone report a disconnect and look back at the graphs/metrics for a clue, we're not seeing anything stand out.

You could also configure Vlan poolin  and named vlans

it is recommended to have no more than 200 users per vlan.

 

Also i noticed something important here

you said

"i see a client associate with different APs throughout the day in the same area, and for whatever reason they're switching bands each time.  I'm not sure if this is causing the loss of connectivity or if it's something else."

 

When you did the wireless site survy did you survy for 2.4ghz? or did you survy fo 5ghz?

i mention this becasue 5ghz coverage is less than 2.4ghz

 

If someone which is connedted to 5ghz band suddenly got a bad signal from a 5ghz band then he will switch to the 2.4ghz band

He cannot roam to another 5ghz band because maybe the other AP which is near the 5ghz band does not reach but the 2.4ghz do reach  and thats why it migh be switching bands...

Do you notice this?

 

Do you have band steering on? or spectrum load banalcer on? or hand off assist feature on?

 

 

 

VLAN  pooling is definitely something I would like to enable.  We're more than 200+ users per VLAN currently.

 

Unfortunately, I was not around when the site survey and installation were done so I'm not sure.  Looking at VisualRF, w/only 5GHz enabled, coverage looks pretty good.  No apparent gaps in the heatmap.

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@thecompnerd wrote:

VLAN  pooling is definitely something I would like to enable.  We're more than 200+ users per VLAN currently.

 

Unfortunately, I was not around when the site survey and installation were done so I'm not sure.  Looking at VisualRF, w/only 5GHz enabled, coverage looks pretty good.  No apparent gaps in the heatmap.

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Please see the document "Optimizing Aruba WLANs for Roaming Devices" on the page here:  http://www.arubanetworks.com/technology/reference-design-guides/ to get information on the correct approach and settings that you can use in your environment.  There are a number of factors that go into ensuring that your environment is properly provisioned, and that is the document that explains this approach.

 

Even if the Visual  RF says that well as far i know to build that you have to import a map of the floor in it, and in some of them you have to put it the measures, you also have to put what are everything in it let say you have to put what is the walls made from the list you got to put and son on... so the visual RF yes its a GREAT tool but is just a good aproximate if it configured propertly, a GOOD one.

 

Anyways you could connect to a 5ghz band on an AP and try to move to another AP to see if you get the disconnection and you see yourslef reasociating to a 2.4ghz?

If you not sure and you want to be really sure you can put the APS on 2.4ghz on air monitor or something like this so it just serve on 5ghz then you will see the real reach of the 5ghz for real for yourseft.. but of course you have to do it when noone is in... and when you done you put it like it was before...

 

I actually cant find a reason besides this of why it will disconnect from a 5ghz band to connec to a 2.4ghz band... if you using spectrum load balancer for example this scenario wont happen because it just work for new clients.... band steering also does not disconnect users...  maybe if you got hand assit on,  well that will disconnect you if you dont have the specified RSSI configured.

 

Anyhways the document that Collin posted is really good you should give it a reading... :)

We seem to have two separate issues: some clients will switch bands and experience a brief loss in connectivity & some clients lose connectivity briefly while staying on the same band.

 

I saw an issue where 8 clients clients dropped from an AP and connected to another AP around the same time.  On the AP that the clients were connected to, the transmit power of the .11a radio dropped significantly (24dBm to 14 dBm then to 8 dBm) around the same time that the clients dropped.  I'm not sure if the clients dropped because the transmit power was so much lower, or if the AP dropped transmit power because there were fewer clients.  I received a few calls about that one from the affected users.

 

I'm not sure that I would consider our environment highly mobile, but I did read the doc.  I'm curious to know about the min/max transmit power.  The doc has a table w/ recommendations for min/max settings.  Our Aruba SE recommended a min EIRP of 15.  If using 15 as a min, the guide suggests a max of 20.  Looking at EIRP values on our APs, most .11g radios are at 9, and most .11n radios are at 25 throughout the day.  If I apply those settings to the default radio profile than the EIRP on my .11g radios will increase, but it will bring down the EIRP on most of the .11a radios since they're operating around 25.  I could create separate radio profiles, but I'm not sure if adjusting the min/max values is even necessary in our environment.  Are there any additional suggestions for setting the min/max transmit power?  I really doubt this is even contributing to our drop problems since EIRP usually seems to be high enough on our .11a radios.

Do you have hand off assist feature on?

what is do is that it will disconnect your client  if it does not have a minimum RSSI

 

Handoff assist is disabled.

Not sure about 802.11h.  Where would I find that in my config?

It is off by default

But just check just in case...

on ap group on rf managment 802.11a radio profile

Also on 802.11g radio profile

you will see a box which it says Advertise 802.11d and 802.11h Capabilities

It should be unchecked(which is the default) It does help when your wireless cards of your clients support it! in the way that it will tell the client what transmit power to use, he will transmit as low as he can so that way it will make less noise in the channel.

 

About the transmit power as far i know the AP can have a transmit power lower than the client but if its higher then the client will be not able to communicate with the AP

 

But i think that the transmit power went down is because he was first talking witha client which it needed that 24db of transmit power... but then it needed to talk with another client in which  it needed less transmit power as like i said the transmit power of the AP cant be higher than the client... remenber the AP just talk to one client at time and i guess it need to change the transmit power now and then... At least thats how i understand it... someone else can confirm this info hopefullysomeone of aruba.

 

I dont know what is the minimum transmit power in which an AP can transmit and also talk with the client... Maybe Someone else can asnwer you that.

Also do you have 802.11h configured? this feature can give issue to some clients  which does not handle this protocol well..  this standard has to be with the transmit power... i think the client and the ap negociate a tells the client what transmit power it need to set.  If you got it on.. i have seen people telling in this forum that old client or old driers give issues in which they cannot connect  or disconnect i think

Advertise 802.11d and 802.11h Capabilities is disabled.

 

Several people, including me, just got kicked off again at around the same time.  2 people were on the same AP and I was on a different AP.  Is there any way to see if the APs are doing anything that would kick us off, like a scan of some sort?  We have VoIP aware scan, Video aware scan, and client aware enabled so it shouldn't be that, but I'd just like to be sure.

VoIP aware scan, it does some kind of packet inspection and he get notice it is a voip call and give it priorization over other packets

Video aware scan same like voip but with video 

and client aware enabled  and the client aware enable means that when a client is connected to ap it wont change the channel.

 

If there a feature that would kick you of the channel... well the other thing i could think off was the hand off assist...

The spectrum load balancer neither the band steering kick you from the ap....

 

Do you have lot of interference? or something like that?

if you send 1000 ping packets  to an ip internallly in your network how which is the  packet loss %?

 

the other thing that i could think off is maybe the battery save mode on the client... if the wireless nic go to sleep and then wake up it could seen like a disconnection...

Interference is very low in the 5GHz band.  On average, around 2% interference.

 

I'm running a continuous ping right now and it's around 1-2% packet loss.

 

At one point I did think that maybe it was the NIC going to sleep, but I don't see how that's the problem when several clients disconnect from the AP at the same time.  It would have to be an infrastructure or environmental issue to happen to multiple clients like that.

Does it happen in an specific area or specific AP?

or does it happens in all aps??

As far as I'm aware, it's happening to several people on my floor on different APs.  We have a medium size campus and it's possible that others are experiencing the issue but not reporting it.

You should enable broadcast filter all on all of your virtual access points to improve performance. You have a great number of users and a good deal of their traffic is broadcast traffic. The fact that it is happening to people on both bands means that it is not localized. Just try dropping broadcasts and take it from there. Many environments use it with great success.

We've enabled broadcast filter all, but we're still experiencing client disconnects.  Even more concerning is that I have APs switching channels while clients are connected.  Client aware is enabled in the ARM profile, and yet I've seen at least two instances in the last day of APs changing channels with clients connected.  I only found that out after I was notified that those clients had connectivity issues around the time of the APs changing channels.  Is there any reason why client aware would not be honored???

 

My SE has created a ticket and opened it with senior support and will talk to them tomorrow.  I've sent them an AP capture from last week when I got disconnected.  The only thing interesting in the capture is a disassociation and deauthenticate frame that were captured around the time I got disconnected.   Not sure if that was coincidence, but hope that support has some ideas.