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Lot of packet drops in a Wireless LAN

Posted on 2014-04-12
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Last Modified: 2014-05-12
Hi,


we have an issue persisting since first day of implementation.

Lot of packet drops from Wireless LAPTOP to other Wireless Laptop and
confirmed that  Over Wire Nettwork they are working fine.

Our scenario is :

                                          Interent
                                                 |
                                          Cyberoam Firewall
                                                |
                                           SG- 300         POE switch
                                           |                                     |    
 Cisco 1602I Acccess points (4 qty)                        Cisco WLC 2504 controller


Brief description :

1. Cisco WLC is connected to Trunk port of SG-300 Switch
2. 4 Access points are connected to Access ports of SG-300 switch
3.  SG-300 switch is L2 mode.

Testing carried :

1. Disable 3 Access points and worked with single Access point but no result still packet drops

2. WMM  disabled and enale cleanair but no result

3. upgraded WLC 7.4.121 codee to 7.6.100 and all registration are happened but issue persists

4. Did Link  test from Switch to controller and Access points , that shows fine.


Help requried :

1. How to debug (COmmands) to see why packet drops getting from a PC to  other PC.

2. Did debug client <MAC> but nothing shown , is there any other commands

3. Any anlayser tools that gives why Packet drops getting


4. Over wire network , speed test showing good but wireless network speed test for internet showing less Bandwidth


Pls advice for debug the issue

Can we connect SG-300 switch in L2 mode to WLC .


Regards
Ram
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Question by:RAMU CH
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Expert Comment

by:Craig Beck
ID: 39996232
Can you provide a show run-config output and a debug client <MAC> output from the WLC please?
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Author Comment

by:RAMU CH
ID: 39996968
Hi ,

Attached the Debug and sh tech outputs ..

Pls do the needful by giving troubleshooting soution.

WLC connected to L2 (SG-300) Switch ..

General in what conditions packets gets dropped in Wireless LAN?

Regards
Ramu
debug-cleint.log
sh-tech
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Expert Comment

by:Craig Beck
ID: 39997508
I need show run-config please.
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Author Comment

by:RAMU CH
ID: 39998341
SH run is available in Sh tech file under - "Show run-config commands".Pls check
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Expert Comment

by:Craig Beck
ID: 39998416
OK, I am aware that the running config is available in the show tech output.

However there's a reason I asked for a SPECIFIC command output.  I want to see the AP stats which is available by issuing the show run-config command.

Please provide what I asked for.
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Author Comment

by:RAMU CH
ID: 40003147
I will share you. but before that .

Pls clear my queiry that :

We have LAPTOPs  which are AC and N comptable Wireless adapters and 1600 series access points also supports N-series %GHZ  and WLC support AC and N supports then why device port peed is showings as 54Mbps instead  Min 150- max 300Mbps speed..

I am from India , hope in India 5Ghz freequency bands are allowed..


Regards
Ramu
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by:Craig Beck
Craig Beck earned 500 total points
ID: 40003375
That's usually because you're not using AES encryption.  802.11n will only work with AES.  It will not work with TKIP.  However, your config says that you are using AES, but with WPA1 only.  Try using WPA2 with AES instead - disable WPA1.

Also, you won't see min 150, max 300 ever - especially with the config you have.  The maximum data-rate at 2.4GHz will be 144Mbps.  At 5GHz it will be 300Mbps, but you have disabled 802.11a so 5GHz is turned off.
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by:RAMU CH
ID: 40003398
Ok, will do that but  But 802.11a supports 54 Mbps only.

Clarify me , If adapter compatible with ac or n channels , if i allow 5Ghz over WLC  , they should automatically get Max through above 54Mbps. Am i correct?




Regards
Ram
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by:Craig Beck
Craig Beck earned 500 total points
ID: 40003441
Ok, will do that but  But 802.11a supports 54 Mbps only.
802.11a is a frequency, 802.11n is an enhancement of 802.11a and 802.11b/g.

802.11n on 5GHz (802.11a) uses up-to 40MHz-wide channels, enabling speeds up-to 300Mbps.

802.11n on 2.4GHz (802.11b/g) uses up-to 20MHz-wide channels, enabling speeds up-to 144Mbps.

If you allow 5GHz on the WLC you also need to enable high-throughput (802.11n) to get faster than 54Mbps.
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by:RAMU CH
ID: 40005877
HI   craigbeck,

Pls find the SH RUN file as requested,

Isssues are

1. Packet loss between same network devices over Wireless LAN

2. Over Wireless LAn devices , ISP bandwidth showing 10-12 Mbps instead 75Mbps over
Speedtest




Regards
Ramu
sh-run.txt
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by:Craig Beck
ID: 40006016
Let's deal with point 2 first.

If your clients are connecting at up-to 54Mbps only they'll never achieve the 75Mbps that your internet link provides.  The PHY link-rate is also always more than the data-rate.  In theory the data-rate can be up-to half the PHY link-rate but due to overheads, environmental factors, etc it's always less than half.  12Mbps throughput at 2.4GHz is around what I'd expect to see with a 54Mbps link.

That leads to point 1...

How are you measuring packet loss?  What tells you there is any loss, or are you just thinking there is loss because of what you believe to be slow throughput?
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Author Comment

by:RAMU CH
ID: 40006198
Pls find the CHannel overlap screen shots..

Pls advice how to prevent channel overlap networks over CiscoWLC 7.6

Regards
Ramu
Overlapping-Networks-on-Cisco-AP.docx
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Expert Comment

by:Craig Beck
ID: 40006223
That's not looking bad.  The WLC will automatically choose the best channel based on RRM and CleanAir (if enabled).

You didn't answer my question...
How are you measuring packet loss?  What tells you there is any loss, or are you just thinking there is loss because of what you believe to be slow throughput?
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Author Comment

by:RAMU CH
ID: 40006230
No, Lots of Ping drops between Wireless Client devices in the LAN itself

Regards
Ram
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Expert Comment

by:Craig Beck
ID: 40006505
I can't see any reason why you would experience packet loss.  The APs can see a few rogue APs but there aren't any that would cause you a substantial issue.

RRM is doing a good job by the look of things.

A few tests...

Connect 2 clients to the same AP.  Ping between them.

Connect 2 clients to different APs.  Ping between them.

Connect one wireless client.  Ping a wired client.

Connect one wired client.  Ping a wireless client.
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Author Comment

by:RAMU CH
ID: 40008575
Why Over Wireless Nework , Internet speed showing 20Mbps around instead 80 Mbps but when the same ISP link connects to Laptop over Switch , it is giving full bandwidth

Regards
ramu
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Author Comment

by:RAMU CH
ID: 40008580
Is WLC 2504 supports 802.11N why i am asking when i configure WLAN , it give Radio types
only a,bg,g ,all

Pls view the screenshot or am i missed any configuraito nto show n channel in the drop-down menu

regards
Ram
802.11n-issue-at-WLC.docx
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Craig Beck earned 500 total points
ID: 40008638
Why Over Wireless Nework , Internet speed showing 20Mbps around instead 80 Mbps but when the same ISP link connects to Laptop over Switch , it is giving full bandwidth
I answered this already...
If your clients are connecting at up-to 54Mbps only they'll never achieve the 75Mbps that your internet link provides.  The PHY link-rate is also always more than the data-rate.  In theory the data-rate can be up-to half the PHY link-rate but due to overheads, environmental factors, etc it's always less than half.  12Mbps throughput at 2.4GHz is around what I'd expect to see with a 54Mbps link.
We have already established that your clients aren't connecting at 802.11n rates, so the maximum they'll get a physical link at is 54Mbps.  As I said, that's nowhere near what you'll achieve - usually at most you'll get 54 / 2 - 10% in a lab environment (somewhere around 22Mbps).  In the real world, 13-14Mbps is the most you should ever expect to see at 2.4GHz with a 54Mbps link.


Is WLC 2504 supports 802.11N why i am asking when i configure WLAN , it give Radio types only a,bg,g ,all
I answered this already too...
802.11a is a frequency, 802.11n is an enhancement of 802.11a and 802.11b/g.

802.11n on 5GHz (802.11a) uses up-to 40MHz-wide channels, enabling speeds up-to 300Mbps.

802.11n on 2.4GHz (802.11b/g) uses up-to 20MHz-wide channels, enabling speeds up-to 144Mbps.
Basically, 5GHz is a frequency and uses 802.11a.  2.4GHz is a frequency and uses 802.11b/g.  802.11n however is not a frequency; it's just an enhancement of the frequency.  On the WLC you can only choose radio frequencies (or radio interfaces) therefore 802.11n is not a valid selection.  To enable 802.11n you have to enable the 'High Throughput' option in the 802.11a or 802.11b/g options in the Wireless tab.
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Author Comment

by:RAMU CH
ID: 40012009
Hi,

Thanks for the information.It's really useful

My querie at this moment:

We have enabled 802.11b/g radio type on WLAN  and enabled 802.11 N and then onwards acheived Morethan 54Mbps.

But few Wireless devices are showing 65Mbps and few are 75Mbps adapter speed.
Why it is like that..

Pls confirm ,

1. end of the day is it depends on Client device adapter specification?
2. Is there any issues wil come if we enable 802.11N in 802.11b/g
3. After enabling , client shows their radio are 802.11bn,what is 802.11bn , why it showing as 802.11bn , why it is not 802.11gn?.

4, WHy clients are not connecting SSID when enable 802.11a radio type , is it because of
client specification


Is there any tool, link or software , command which gives information about Wireless client adpater compatibility and support data rates

Regards
Ram
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Author Comment

by:RAMU CH
ID: 40012171
Waiting for reply, pls respond
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Assisted Solution

by:Craig Beck
Craig Beck earned 500 total points
ID: 40020924
1] Correct, the card may only be 1x1 or 2x2 for example. That will determine data-rate.

2] Only if you enable 40MHz-channels.  This will create co-channel interference.

3] That's vendor-specific. Its still 802.11g if the client supports it.  The standard detailed 802.11b at 2.4GHz that's all... Nothing wrong.

4] If you ONLY enable 802.11a the 802.11b/g clients won't work unless they also support 802.11a.

Check the manufacturer's website or device manual for detailed specifications.
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Author Comment

by:RAMU CH
ID: 40022071
Thanks for the reply..

Overall this case , i have learnt basics on Wirelss..

Now it's time close the request..

Last one :
When i run  InSSIDer tool , i have observed Co-channel interference and Overlapping
Networks

My questions are :

1. What is co-channel interference , adjacent channel interference.
2. what is the difference between both
3. Is cochannel interfernce is common in Wireless networks?
4.How can we eliminate cochannel and overlapping networks?

what is the benifit of  non-overlapping channels 1,6,11 than ovelapping channels

Regards
Ramu
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by:Craig Beck
Craig Beck earned 500 total points
ID: 40024720
I'll answer this first... it's fundamental to any efficient WLAN.
what is the benifit of  non-overlapping channels 1,6,11 than ovelapping channels
Let's say you have 11 classrooms all next to each-other.  In room 1 you are teaching Maths.  In room 2 you are teaching Cookery, but you can hear what's happening in the Maths lesson.  In room 5 you can just faintly hear the Maths lesson, but not much.  In room 6 you can't hear anything from room 1.

That's basically it.  If you have a lot of conversations going on, all in different 'subjects' (let's say) it gets complicated and it makes it hard to understand what's going on, especially if a lot of people are trying to talk at the same time.

That's why channel selection is important.  If you put all of those lessons in the same classroom it would be difficult to understand what was going on, unless that room was a large stadium maybe :-)

In summary answers to your questions are...

1] Co-channel interference is generally considered to be interference caused by the same system on the same or surrounding channels as another transmitter/receiver.  Adjacent channel interference is interference on the same or surrounding channels by a device which is not part of the same RF system.

2] Answered in [1].

3] Co-channel interference is common in WLANs where no dynamic or automatic RF management features are available.  The beauty of dynamic/automatic RF management is that it can adapt your system to the surrounding environment and mitigate (to a degree if not completely) the effects of interference.

4] There's no definite way to eliminate co-channel interference unless you meticulously plan YOUR WLAN deployment.  A good RF survey is essential for this.  You also need to know what type of network you want to deploy (data, voice-ready, location) and plan for that.  The problem with eliminating overlapping networks is that the licence-free bands are available for anyone to use.  That means you have no jurisdiction over who uses what channels (although at 5GHz you 'can' ask anyone who interferes with your network to change their channels if the link is registered).
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Author Closing Comment

by:RAMU CH
ID: 40058234
Good
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