Meru Performance with 20 Windows Laptops...

[_techie_]

Hi,

 

We have an MC3000 controller, 320iAP's and 20 HP 250 laptops in our Prep school. The laptops are N compatible wireless.

There are 8 classrooms with 6 AP's feeding the classrooms, and one in the staff room/reception area.

There is Approx 1 AP per classroom, with 100Mb uplinks to the AP's via an HP 2530 PoE switch. 1Gb backbone via Fibre and uplinks back to the core switch and controller. No error on any of the switches, so I am slightly confused as to what's going on. Meru performance around the rest of the school is fine, and we have 10 laptops per floor in science with 1 AP per classroom there without complaints either!

 

Logon performance is slightly reduced than with a normal wired LAN connection, (Approx 50 secs vs 30 secs for the Wired).

However this was testing one laptop. The connection speed recorded on the laptop was 65MBps, but I am getting complaints about slow and failed logins with pupils (no error messages were able to be provided however). This seems like some kind of bottleneck/throughout issue. Would having 1GB uplinks resolve the issue to each AP? I think that this would just push the bottleneck to the Gb uplink so would not solve the issue! I have been wandering around with one of the laptops and the Meru system director, and hopping between AP's is fine, and connecting to all AP's is fine. All AP's are reporting in fine too to the controller.

 

Is there any decent wireless troubleshooting tools, or someway of determining where a possible problem.could be within the rest of the network?

 

Cheers

Mark

[xenonive]

Sounds like the wireless is working in 20mhz mode rather than 40mhz mode . On wireless N cards 20mhz mode gives you up to 65mbps connection and 40mhz gives up to 130mbps in single band mode . I believe dual band gives up to 300mbps connection but not 100% sure so hopefully someone can correct me .

[psydii]

Is the problem isolated to one location?

 

What wireless cards are in use?

Are you on the latest driver and firmware versions for end user devices and infrastructure?

If windows 7 clients: Do you have the enterprise hotfix rollup deployed on your clients and servers?

If Windows 8 install the latest updates (I.e 8.1 Update) both client and server side.

 

Do you have upd broadcast enabled? (Bad idea)

Do you have multicast enabled? (Bad idea)

Are the laptops controlled by the same set of GPO's as the rest of the site? (Folder redirection/offline file default settings can cause this)

How much data are you trying to get over the network for each login? (Related to above)

How are windows updates or antivirus updates configured?(related to above)

 

Are you running SCA or MCA? (Perhaps there is channel overlap in this location)

 

Do you have 2.4 and 5ghz channels available? (And do your cards support both frequencies?)

Edited May 18, 2014 by psydii

[_techie_]

Thanks for both your replies guys...

The wireless cards are Qualcomm integrated to the laptops, and yes we are on the latest drivers. As regarding firmware, I presume you mean updating the BIOS in this instance?

 

I do have multicast enabled, this was to allow our apple tv's and iPads work together. I am unsure whether broadcast is on, but I doubt it. The problem only seems to be located in our prep department.

 

It is windows 7 enterprise, we rollout all updates via WSUS, but how would I find out about the hot fix rollup? All updates are downloaded to the laptops in the evening. AV scans are also scheduled for this time, 6pm prior to the WSUS updates.

 

Apart from a few applications, the policies are the same. We have offline files disabled and all users have folder redirection for my docs, music, favourites etc etc.

 

Generally at Logon we have roaming profiles which can vary between 3-10MB dependant on user. I am looking at mandatory profiles for our prep students, as we do have lots of niggly issues with profiles at present. Hopefully by doing this I can keep the profile small and under control.

 

I am unsure on your last few questions!

I presume MCA is something related to multi channel, and SCA is single channel?

 

What benefits would having 5GHz and 2.4GHz do?

 

I am aware that the firmware on the access points was 'downgraded' to work with the current firmware on the controller. We are due a controller update in the summer to the 3200 series and system director 6.

 

After what you have mentioned, I am now possibly considering putting the Apple TV's and Staff iPads on their own VLAN, Subnet and DHCP scope, so that I can enable multicast just for that VLAN.

 

Thanks for your help, I now have a starting point for moving forwards.

 

Cheers

Mark

 

 

 

Is the problem isolated to one location?

 

What wireless cards are in use?

Are you on the latest driver and firmware versions for end user devices and infrastructure?

If windows 7 clients: Do you have the enterprise hotfix rollup deployed on your clients and servers?

If Windows 8 install the latest updates (I.e 8.1 Update) both client and server side.

 

Do you have upd broadcast enabled? (Bad idea)

Do you have multicast enabled? (Bad idea)

Are the laptops controlled by the same set of GPO's as the rest of the site? (Folder redirection/offline file default settings can cause this)

How much data are you trying to get over the network for each login? (Related to above)

How are windows updates or antivirus updates configured?(related to above)

 

Are you running SCA or MCA? (Perhaps there is channel overlap in this location)

 

Do you have 2.4 and 5ghz channels available? (And do your cards support both frequencies?)

[psydii]

If you LAN is fairly flat, you will see performance improvement if you disable multicast. As you say, an alternative would be to ensure the wired side was a vlan only for your wireless clients and the apple TVs. SD6 is supposed to be a huge improvement in is regard.

 

2.4 and 5ghz gives you twice the bandwidth, and clients in general load balance themselves between the two quite nicely.

 

I'd be investigating whether you have some rogue/misconfigured software on one/some of the machines in that space... I've seen spotify and activinspire cripple a wireless broadcast domain due to continuous rapid fire writing of tiny files to what the applications assumed was the local disk, but thanks to folder redirection a was a network share mounted over wifi.

 

On the topic of hotfixes:

http://www.edugeek.net/forums/windows-7/133978-list-hotfixes-folder-redirection-windows-7-clients.html

Edited May 18, 2014 by psydii

[_techie_]

Our prep domain laptops are also on the same vlan (1-default) as the Apple TV's (wired into LAN) and only certain iPads are allowed onto the same SSID.

I also have another two SSID's which use a seperate VLAN, and subnet and DHCP scope, but have not enabled multicast on this SSID. Would enabling IGMP on all switches make any difference (clutching at straws here). What exactly are the negative effects of using multicast (a brief explanation of the issue, as I understand what multicast is, just not quite how it can be applied etc.)

 

I do have another issue in that one iPad user also uses vnc viewer to wander around his classroom and teach from (connects to his teachers desktop PC.) as well as use the Apple TV in his classroom (that's another issue altogether!).

 

Cheers

Mark

[psydii]

Basically multicast becomes broadcast over wireless, and on some configurations is broadcast to every client that has 'subscribed' for notifications, so for one wired-side multicast packet you might have as many wireless packets as there are clients.

 

Also ssid only chop up the spectrum logically. It is still a shared medium so what happens on one ssid affects all ssids on that channel/radio.

 

The quality of the wireless devices in play is also an issue.. 2x2:2 is good, but some cheaper devices are only 1x1 (especially older units and tablets) and they take longer to transfer the same amount of data, consuming a disproportionate amount of bandwidth. You don't have any 802.11b devices around do you?

 

 

 

Don't forget to check for rogue wifi though.. Inssider is good for this. If there is channel overlap you will need to either shutdown the rogue service, or change your own channel.

Edited May 18, 2014 by psydii

[_techie_]

Hi.

 

We only have active inspire on wired teachers desktops, albeit they are on the same VLAN, and broadcast domain as said laptops. How would I find out about the 2x2:2 stuff, and what does it actually mean?

 

I did have a look at inSSIDer, but didn't get any further with it, can you use it to gauge wireless coverage and "black spots/poor coverage"?

 

Seems like I have some more testing tomorrow to do, and experimenting with settings on the meru controller, and getting the stopwatch out!

 

As far as I am aware, we (IT Support) have no 802.11b devices, but we do allow BYOD (on seperate SSID, VLAN and subnet). Since the AP's are sharing wireless signal, would this have any impact?

 

Also, if I was to setup another VLAN, SSID, and scope/subnet just for the Apple TV's and iPads, with multicast enabled just for that SSID, would the performance just for those devices suffer, or is it just a limitation of a Windows kit not being upto the job??? LOL

[andyfield]

We have some HP 250 laptops on a Meru wireless. They are fine except when in close proximity with each other. For some reason they interfere with each other causing all sorts of issues. Walk one out of the classroom and login is fine even on same AP. Had to advise teachers to space them out in classroom.

[_techie_]

Turns out it was the multicast flag on that SSID. Turned it off, and now laptops speedy again! Happy days.

 

Cheers

Mark