Client data rates are fluctuating

[vijay kumar]

Hi All,

We have created temporary wireless setup for our users in one floor with 13 APs. In which 9 of them 'n' supported AP's and remaining are only b/g.

we have conducted proper wireless site survey and we have placed the AP according to that.  But the issue is , in clients laptop we could see that data rates are chaging from 144.mbps , 72 Mbs ,...... and finally with 1mbps  .And they are facing very slowness in the network .

Wheras in other buliding we have only 3600Ap and there is no issue for the clients there. Data rates are constant. In these two cases , all Ap's are connecting to the same WLC  and getting the same config from WLC. So kindly suggest me is this issue is related with mixed mode AP's ?

Thanks ,,

Regards,

Vijay.

[Leo Laohoo]

But the issue is , in clients laptop we could see that data rates are chaging from 144.mbps , 72 Mbs ,...... and finally with 1mbps  .And they are facing very slowness in the network .

Make sure the drivers of the wireless clients are up-to-date.  Go to the manufacturer of the wireless card (do not go to the website of the laptop's manufacturer) and see if there re newer drivers.

If the drivers are up-to-date, what happens if you disable 802.11n on the client side?

[vijay kumar]

The drivers of wireless NIC are uptodate in clients laptop . We tried to disable the same . But again the datarates are reducing from 54 Mbps to 1 Mbps .

[Rasika Nayanajith]

Disable all data rates below 12Mbps &make 12Mbps mandatory in both 802.11a/n & 802.11b/g/n bands & see if that helps. Always prefer to have 802.11n capable AP rather having mix of 802.11a//b/g only AP with 802.11n ap since client will tend to stick old APs without roaming to n capable APs.

Are you having this issue in both bands  or only 2.4GHz band ? What is the WLC software version you are running ?

HTH

Rasika

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[vijay kumar]

We are having issues on both bands . we are running version of 7.4.100.60

[Rasika Nayanajith]

This is a not a good software code to be in. I would suggest you to upgrade your WLC to 7.4.121.0 (7.4MR2). Also make sure your WLC FUS is 1.7.0.0 as well. Here is the release notes for this 7.4MR2 code & FUS 1.7.0.0 upgrade.

http://www.cisco.com/en/US/docs/wireless/controller/release/notes/crn74mr02.html
http://www.cisco.com/en/US/docs/wireless/controller/release/notes/fus_rn_1_7_0_0.htmlhttp://www.cisco.com/en/US/docs/wireless/controller/release/notes/crn74mr02.html

We have experienced few nasty bugs with that code (specially C3600 & Clean Air enabled). Here is one example

CSCug46718
Most 802.11 client 2.4GHz authentications will stop after a period of  time causing clients to roam to further AP’s, or possibly no longer see  the SSID from the AP. However, connectivity to certain clients may  remain unaffected.
Only occurs on 2.4GHz band radio with CleanAir capable APs (Cisco  Aironet 2600, 3500, and 3600 series Access Points) with software release  version 7-4-100-0 or 7-4-100-60

Here is my experience with 7.4.x code & based on this strongly recommended you to upgrade 7.4MR2.

http://mrncciew.com/2013/02/10/day-0-with-wlc-7-4-code/

HTH

Rasika

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[vijay kumar]

Actually we are planning to add 802.11ac adapters in our AP . Can u suggest any stable version of 7.5 release that supports this module . And in our case , we could see that client is connected in one AP only . it is not roaming between AP's  . Only the data rates continiously reducing.

[Rasika Nayanajith]

In 7.5.x train only one release is available (7.5.102.0). So no other alternatvies & you have to go for that version if you want to support 3600 with ac module. Here is the release notes for 7.5.102.0

http://www.cisco.com/en/US/docs/wireless/controller/release/notes/crn75.html

Another alternative is to go with 7.6.100.0 (recently released - 18th Dec 13) if you have any plan to us 802.11ac AP like 3700 series in future.Here is the release note for this code

http://www.cisco.com/en/US/docs/wireless/controller/release/notes/crn76.html

Hopefully another code (8.x) may come during the mid  year. So 7.5, 7.6 may not have long life. But if you require this 802.11ac feature, then you have to go for one of those code in the mean time

Also make sure you are aware of the compatibility between these software codes & Prime/MSE/etc if you already having those. (may not upto date with 7.6 & 3700 release, but still useful if you go with 7.5.102.0)

http://www.cisco.com/en/US/docs/wireless/controller/5500/tech_notes/Wireless_Software_Compatibility_Matrix.html

HTH

Rasika

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[Leo Laohoo]

We are having issues on both bands .

Hmmmmm ... This is beginning to sound like environmental. 

Can you describe how are your APs installed?  What model of AP?

Distance between the client(s) and the AP? 

[Scott Fella]

First off... like what Rasika mentioned and is a best practice....mixing 802.11n with non 802.11n will always cause issues.  802.11n devices will tend to only roam to 802.11n access points, so its better to disable 802.11n until the building or your roaming area are all 802.11n compatible access points. 

The other issue as the others have explained, is your data rates.  Without knowing how well your coverage is, you can disable the lower data rates,which is a good thing, but it can cause poor coverage in areas that might be far from an access point. 

In a mixed environment like what you have, if you continue to keep 802.11n available, then do expect issues, because the client in the end is the device that will decide what access points it will associate to and want to roam to.  Compare this to your other sites with all 3600's... no issues... Even with the same configurations, the site with 3600's are fine, so disable 802.11n on the mixed site and you should be fine.

Thanks,

Scott

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[vijay kumar]

six 3602 and two 2600 remaining 5 ap's are old model a/b/g only supported ap's.

Even though client is right below the ap, the datarate/ connection speed is fluctuating.

So here few ap's are a/b/g and few are `n` supported. Whether this causing unstable situation..

[Scott Fella]

Never mix... your better of either disabling 802.11n or removing the non 802.11n access points.... clients make the decision and as you can see, they are freaking out.

Thanks,

Scott

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[Scott Fella]

This is not only our best practice in the Cisco world, its also a best practice in the Aruba world along with other vendors.

Thanks,

Scott

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[vijay kumar]

Thanks scott,.. Let me try disable n and see. We will change to same model ap soon.

Could you please give me some cisco link stating that mix mode will cause this kind of issues. ...??

Thanks in advance

[Scott Fella]

I would... I have a few customers who have a mixed environment with Cisco or Aruba equipment and that is what we had to do.  Now as far as data rates goes, disable the lower data rates if you can.  The lowest mandatory rate is where the beacons will be sent and the highest mandatory rate is where multicast will be sent.  You don't have to configure two mandatory rates, but one is required.  The lowest mandatory rate, the client has to be able to connect to.  Many time, 18 mbps or 24 mbps will work and you still can support 12 mbps if needed.  If you don't need to support 802.11b clients then I would disable all data rates below 12 mbps.  Again... this works well if you have good RF converge.

Thanks,

Scott

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