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ASK THE EXPERTS - CISCO CLEAN AIR

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Jan 3rd, 2011

Welcome to the Cisco Networking Professionals Ask the Expert conversation.   This is an opportunity to learn about the last generation of access points from Cisco and the integration of the clean air technology to locate and mitigate interferences with Nicolas Darchis and Federico Ziliotto. Nicolas is a wireless and Authentication, Authorization and Accounting expert for the Technical Assistance Center at Cisco Europe. He has been troubleshooting wireless networks, wireless management tools, and security products including Cisco Secure Access Control Server or Cisco Network Access Control since 2007. He also focuses on filing technical and documentation bugs. Nicolas holds a bachelor's degree in computer networking from the Haute Ecole Rennequin Sualem and a master's degree in computer science from the University of Liege. He also holds CCIE Wireless certification #25344.  Federico is a Customer Support Engineer at the Cisco Technical Assistance Center in Belgium, where he specializes in solving high-severity issues in wireless networks, network admission control setups, identity based networking and 802.1X setups, Authentication, Authorization and Accounting solutions, and Cisco TrustSec. He holds an engineering degree from the University of Padova, Italy, with specialization in telecommunications. Federico holds CCIE Wireless certification.

Remember to use the rating system to let Nicolas and Federico know if you have received an adequate response.

Nicolas and Federico might not be able to answer each question due to the volume expected during this event. Our moderators will post many of the  unanswered questions in other discussion forums shortly after the  event. This event lasts through January 14, 2011. Visit this forum often to view responses to your questions and the questions of other community members.

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pyrichglobal1 Tue, 01/04/2011 - 10:42

I wish to find out the possibility of using the AIR-ANT2506 2.4Ghz bridge antenna on the AIR-LAP1242-E/AK9 AG Access Point in AP mode and the possibility of clients such as mobile laptops associating with this antenna, even at it's farthest coverage range.

fziliott Tue, 01/04/2011 - 11:10

Hi Chidubem,

The antenna type AIR-ANT2506 is compatible with the 1240 series APs, as confirmed by Table 1-1 in the following official guide:

http://www.cisco.com/en/US/docs/wireless/access_point/1240/installation/guide/1240hig2_book.pdf

As described in the initial note of this discussion, please note that this Q&A session is reserved for questions on the CleanAir technology.

1240 series APs and the AIR-ANT2506 antenna type have nothing to do with CleanAir: I would recommend to please look for recommendations on your questions through other more general CSC communities.

Thank you,

Fede

--

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Leo Laohoo Tue, 01/04/2011 - 12:58

Hi Chidubem,

Create a separate topic and ask the same question.  I want to know more about how you are planning to deploy this.  I don't like the smell of what you are trying to achieve.

DigitalAirWireless Tue, 01/04/2011 - 15:38

Hi there,  Can u tell me what licences are required to deploy this?? WCS,WLC and MSE  Thanks!

Leo Laohoo Tue, 01/04/2011 - 17:16

For WCS, you need WCS Plus.  If you purchase the eco-pack (a box of 10) of the 3500, the WCS Plus is free.

b.garczynski Wed, 01/12/2011 - 14:25

To clarify on the WCS license. Is it true that you get the same AP count of WCS-PLUS license that you buy in the eco pack? For example, I am a new Cisco wireless customer and I buy a 10 pack of 3500i APs. Do I instantly get a 10 AP license of WCS-PLUS or is this simply an upgrade from 10 WCS-BASE to 10 WCS-PLUS? If this is truly a WCS-PLUS one for one license would that basically make WCS free for this type of customer?

Thank you,

Nicolas Darchis Thu, 01/13/2011 - 00:30

When you take the eco pack, you get an upgrade license. This means it "upgrades" a normal WCS license to a PLUS license.

The good side is that with a 10-eco pack you get an upgrade for 100 APs.

Example :

You have 90 1242s. You have a WCS-100 AP standard license.

You buy a 3500 10-eco pack. Your WCS license of 100 APS is used at the maximum of 100 APs. The free upgrade you received means you can have the PLUS feature with all 100APs.

Hope it clarifies.

Nicolas

hkisadmin Thu, 01/13/2011 - 00:31
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>>> ndarchis 01/13/11 16:30 >>>

Simon Lau,

A new message was posted in the Discussion thread "ASK THE EXPERTS - CISCO CLEAN AIR":

https://supportforums.cisco.com/message/3268560#3268560

Author : Nicolas Darchis

Profile : https://supportforums.cisco.com/people/ndarchis

Message:

Nicolas Darchis Tue, 01/04/2011 - 22:55

Hi,

WLC- doesn't matter

WCS - As leolaohoo said, you need the Plus.

MSE - It's the usual context-aware license but just be aware that interferers count as clients.

Nicolas.

DigitalAirWireless Wed, 01/05/2011 - 01:46

Nicolas,

i guess there is a few different setups?

1. What functionality do you get if you only have a WLC and no WLC, MSE?

2. What functionality do you get if you only have WLC and WCS with just a BASE license?

3. What functionality extra do you get by having a WLC, WCS and Plus license?

4. What functionality extra on top do you get if you have a WLC, WCS and Plus license with the context-aware license.

Guess i am just trying to work out the difference in functionality between all set-ups so i know for each potential client what is required depenng on what they require.  For some new clinet it might be good enough just to know that there is inteference which is being picked up mainly by a certian AP but they are not to bothered about locating this on a map and will find it manually.

Thanks

Nicolas Darchis Wed, 01/05/2011 - 02:12

Hi,

WLC alone, will be able to detect interferers. Here's an example of the "monitor->clean air" page :

AP NameRadio Slot#Interferer TypeAffected ChannelDetected TimeSeverityDuty Cycle(%)RSSIDevIDClusterID

So you can know what interferer it is, what are its caracteristics at the current time. WLC will also send traps and syslogs accordingly

WLC can also give air quality indicators in order to average the quality of an area around an AP.

If you have WCS without the plus license, it's pretty much the same. You can't locate or have clean air stats in WCS.

With the plus license on WCS, you can locate the interferer and see the statistics through time with graphs, etc ... It also correlates the information sent by multiple WLCs if several APs saw the interferers and they are on different WLCs.

MSE will allow to track interferers in "real-time" (not exactly real, but close enough) on the map.

I hope this clarifies.

Nicolas

fziliott Wed, 01/05/2011 - 02:16

Just one quick add-on regarding your question #4 ;-)

MSE will be the only device capable of merging Interferer Device Reports (IDRs) from different WLCs.
So only with MSE you won't run into the risk that an IDR for the same interferer detected by different WLCs is actually reported as two different interferers/IDRs (potentially possible when having mutliple WLCs, but no MSE comparing data from those WLCs).

Let us know if further clarifications are needed,

Fede

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hkisadmin Sun, 01/09/2011 - 22:28

Greetings

I know it's possible but I wonder if it is advisable to configure multicast on wireless network.

We have 3 WLC 5508 with 7.0.98.0 code and Base license

we have over 160 AP's running N

the clients are connected in a great big address pool - with possibility of 8000+ host ip's

we currently have over 1000+ clients connecting

Management expects wireless to work like a wired network.

They want to enable multicast for applications like Apple Bonjour and other programs and also for streaming video.

I am of the opinion it's not the greatest of ideas.

I see people enabling multicast but not on the scale with the user base we have.

any advise

also would there be any performance issues if clean air is enabled?

cheers

Nicolas Darchis Sun, 01/09/2011 - 23:12

Hi Simon,

CleanAir is a separate chipset in the AP and detects interferences with a dedicated hardware, it can then not have any impact on AP performance at all.

Now regarding multicast ... Let's first explain why it's generally not a good idea and finish with possible alternatives.

Over the air, a multicast is pretty much like a broadcast. In the sense that if an AP sends a multicast, it keeps the air busy for all the clients of that AP, so regardless of the amount of clients subscribed to the stream @ that AP, the performance will be the same.

Because of the horrible consequences if it was the case, the multicast frames are not ACKed by anyone. We're not talking about TCP ACK or anything but usually every single frame over the wireless is acknowledge between client and AP. That's the only way to know if there has been a collision or not.

So because there is no ACK, there is no retransmission. And because wireless is a shared medium, collisions do occur as normal part of the medium. So even in good conditions, there will be a bit of packet loss. In case you have external interferers or high number of clients, then the amount of lost packets will drastically increase and the stream performance is then not acceptable.

Furthermore, because the AP doesn't know how far are the multicast-subscribed clients located, it cannot know if the clients will be able to receive the frame at the maximum data rate (54,144 or 300Mbps). Maybe one of the subscribed client is at the border of the coverage cell and can only transmit at 24Mbps due to the distance. When doing unicast, this is acceptable because close clients get their data at 300mbps and only the far away client is talked to at 24Mbps but in a multicast, .... So as conclusion, the WLC will ALWAYS send the multicast stream at the highest configured data rate. Which is often between 1 and 24Mbps but rarely more.

On the solution side :

-Starting from 7.0 software version, the feature "DirectStream" is there to bring a possible solution. The mutlicast is still multicast over wired : so only the APs having subscribed clients will received the data. But over the air, the AP unicasts the stream to every subscribed clients.

Advantages : Retransmissions are possible, data is acknolwedged, data is sent at the fastest rate acceptable for that particular client.

Inconvenients : If you have a lot of subscribed clients per AP it might not be good to unicast to all of them from a performance perspective. DirectStream usually performs better than normal multicast with 7 or less subscribed client per AP.

-If you have a lot of clients subscribed to your multicast stream on each AP, the "normal" multicast may be your best choice. In this case, you can configure a much higher data rate as "mandatory" so that the multicast stream is sent more rapidly. But be aware that this prevents transmission of the stream to clients that would be a bit far from their AP.

Out of experience, the 2.4Ghz band is usually quite busy (only 3 channels, lots of devices, ...) and it's rare to see a good video stream on multicast over 2.4Ghz unless you are using DirectStream.

On 5Ghz, it's quite feasible to have a good stream using the "normal" multicast.

I hope it clarifies !

Nicolas.

hkisadmin Sun, 01/09/2011 - 23:14
      • THIS IS AN AUTOMATED RESPONSE - DO NOT REPLY THIS EMAIL ***

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If you are a Repulse Bay employee please use the Web Help Desk (http://help.hkis.edu.hk/) for help requests.

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>>> ndarchis 01/10/11 15:12 >>>

Simon Lau,

A new message was posted in the Discussion thread "ASK THE EXPERTS - CISCO CLEAN AIR":

https://supportforums.cisco.com/message/3265364#3265364

Author : Nicolas Darchis

Profile : https://supportforums.cisco.com/people/ndarchis

Message:

ramarao Mon, 01/10/2011 - 06:25

Hi,

I would like to know more on the statement called " This is an opportunity to learn about the last generation of access points from Cisco ". Does this means there will be no more new models.

Thank you

Rama

Nicolas Darchis Mon, 01/10/2011 - 07:08

Rama,

the "last" in that sentence means "most recent" and not "there won't be any new one after this one".

Nicolas

fziliott Mon, 01/10/2011 - 07:09

Hi Rama,

The expression "last generation of access points from Cisco" means that this is the latest/newest generation (so the last one as of the present day).

It does not mean that this will be the last APs that Cisco will ever design/produce.

More fun to come in the future ;-)

Regards,

Fede

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ramarao Mon, 01/10/2011 - 07:35

Hi Nicolas/Fede,

Thanks for clarification, I have a few units coming in soon, but it will be a mixture of 1252's and 3500's.  Few Questions:

1. Would there be any difference on M-Drive technology between clean-air and other AP's

2. Since the clean-air technology is based on hardware, can it be turned off as well, just to know.

Many thanks

Rama

Nicolas Darchis Mon, 01/10/2011 - 07:45

Hi,

1) For everyone, the "M-drive" marketing term englobes the following :

  • ClientLink improves reliability and coverage for legacy clients
  • BandSelect improves 5 GHz client connections in mixed client environments
  • VideoStream uses multicast to improve multimedia applications

These 3 features are software features available also on non-cleanair AP models. So those feature stay identical on Cleanair AP models. No change at all.

2)Yes you can turn it off. On the WLC web page : "Wireless" - >802.11a/n -> Cleanair -> You have cleanair settings there and a general checkbox to disable it.

Same goes for the 802.11b/g menu to disable clean air on 2.4 Ghz.

rob.simkins Mon, 01/10/2011 - 07:37

Hi guys,

I understand that the spectrum analysis runs in parallel to the regular AP duties so that client connectivity can be maintained.  Can you explain the clock cyles involved in simple terms with regards to the AP going off-channel to detect interferers?  Also how this impacts clients, or if there is a hold-off period when the AP is busy.

Thanks in advance

Rob

fziliott Mon, 01/10/2011 - 07:45

Hi Rob,

CleanAir is run in parallel with standard client serving processes, so no need for the AP to go off-channel.

Interferers will be detected only for the same channel for which you are serving clients, if you are using a local mode AP.

If using a monitor mode AP, then the AP will cycle through different channels (without serving clients) and detect interferers on multiple channels.

Regards,

Fede

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rob.simkins Mon, 01/10/2011 - 07:55

Thanks Fede that makes sense.

So with regards to off-channel scans for say IDS?  Do these still happen?

Another thought is regarding RTLS - will the AP assist with location of interferers that aren't on the operational channels?

Regards,

Rob

fziliott Mon, 01/10/2011 - 08:03

Sure Rob,

We can think of CleanAir as of a parallel feature set, but separate with regards to the previous "standard" features of other APs.

So for example, RRM off-channel scans will also still works the same as for other non-CleanAir APs.

For locating interferers, a CleanAir AP in local mode will definitely help to locate interferer, but only on the channel on which it is serving clients.

CleanAir APs in monitor mode can help locating interferers on multiple channels.

Regards,

Fede

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danhosking Wed, 01/12/2011 - 16:15

Hi,

I am looking for the procedure to completley default a 3502i AP and reset the username and passwords. It has previously been associtated with a controller at another clients site. All the documentation I have found so far outline procedures for older APs.

Thanks Daniel.

fziliott Thu, 01/13/2011 - 00:46

Hi Daniel,

To reset an AP we could have different options.

1. Through the MODE button:

- Power off the AP.

- While keeping the MODE button pressed, power on the AP.

- Still keep the MODE button pressed until the Status LED turns to red and then release it:

http://www.cisco.com/en/US/docs/wireless/access_point/3500/quick/guide/ap3500getstart.html#wp46485

This, however, may not fully reset the AP to its factory defaults.

2. By downloading the recovery image to the AP and let it reload after that. Through a telnet/console connection:

debug capwap console cli

archive download-sw /overwrite /reload tftp:///

The recovery image for 3500 APs can be found on Cisco.com:

http://www.cisco.com/cisco/software/release.html?mdfid=283307702&flowid=16363&softwareid=280775090&release=12.4.23c-JA&rellifecycle=ED&relind=AVAILABLE&reltype=latest

Regards,

Fede

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craig.eyre Sat, 01/15/2011 - 10:54

HI  Nicolas and Federico,

I'm currently in the site survey stages of a 500 ap deployment (3502i and 3502e). We will be running 2 5508's, WCS and MSE and majority of ap's will be 3502i's. Myself and my coworkers have questions regarding the signal coverage from the internal antenna of these devices. We are planning to mount most of the ap's with internal antenna parallel to the floor as we think that gives the best signal coverage. What are the down falls of mounting a 3502i horizontally towards the "users"? If we have to mount horizontally should we be using the 3502e? This is in a library area, 50 foot ceilings, high density, future voip, mostly concrete and and many bookshelves. Do books cause a lot of signal loss if you have multiple rows of bookshelves? I know the bookshelf itself being made out of metal will cause signal bounce but I wonder about the books. If we put ap's up in monitor mode only, what is the recommendation for number of monitors per number of client accessing ap's?

thanks for any info you can provide me with.

craig eyre

jwarner Sun, 01/16/2011 - 16:26

A library with 50 ft ceilings?  Seems unlikely.

I just surveyed our AP deployment in the main campus library.  "Survey" might be to generous a word -- I wandered around with a laptop and recorded some RSSI numbers at 2.5 GHz.  The big surprise is that there is a lot more floor-to-floor penetration through poured in place concrete than I would have imagined. If possible, you should stagger the pattern of your deployments so that APs on adjacent floors are not directly lined up. In california, poured concrete is more popular than steel-frame construction for libraries because it is stronger.  Books weigh a lot.

-jim warner, UCSC

Nicolas Darchis Sun, 01/16/2011 - 23:45

The APs with internal antennas (1130,1140,3502i) have a dome-like coverage, so they are designed for ceiling placement.

Imagine a dome on an AP placed on a wall, perpendicular to floor, the coverage will be awesome on the floor above and below the AP but 20 meters from the AP on a horizontal plane, you'll get nothing. For wall placement, a 3502e with antennas correctly oriented is then better.

The height of your ceiling is a bit of a concern and that means that the coverage on the ground will not be so exciting. However, it would sound like ceiling placement is recommended rather than wall placement since that would mean higher number of obstacles (all the book shelves).

Hope it helps.

Nicolas

craig.eyre Mon, 01/17/2011 - 06:30

Thanks for the quick replies everyone.

Nicolas,

When you mention "but 20 meters from the AP on a horizontal plane, you'll get nothing" is the 20 meters the maximum distance of the "dome" so to speak? The library has a very high ceiling and we've already recommended no placement on the ceiling. We'll most likely place them in a grid like system on the concrete pillars as cabling and conduit routing are a bit difficult.

Thanks,

Craig

Nicolas Darchis Mon, 01/17/2011 - 06:34

The number "20" was a random value. I actually never measured how many meters the coverage goes when the AP is placed on a wall because it's not supposed to :-)

I don't know the maximum heigth that people put the AP and still had good coverage

Stanley.masaki Wed, 01/19/2011 - 15:43

Hello;

I have a deployment of 5508 WLCs and 3500i APs.  I have CleanAir configured and enabled.  I am constantly getting Interference threshold violations, however, when I look at the CleanAir Interferer Count in WCS there are no devices listed.  Could it be that since these APs are in local mode that the interferer is not on channel 1, 6, or 11? 

Thanks

Stan

Nicolas Darchis Mon, 02/21/2011 - 23:14

Hi Stan, sorry but the event was closed. Don't hesitate to ask your question in the forum directly

abakrbshat Mon, 02/21/2011 - 04:00

hi,
i need to your advise regard below matter:
i have router and switch and Aironnet 1210 AP,so i need to creat two network on the AP one for emplyees and other one for Guest but the Guest network for internet only.

how can i do that?

Nicolas Darchis Mon, 02/21/2011 - 23:15

Hi Amer, please post your question directly in the forum. This "ask the expert" event is only about clean air (which is not your question) and is also closed since some time.

Nicolas

harisivaji Mon, 04/25/2011 - 13:38

Hi ,

Iam new to this field of Wireless network. I got a basic doubt that how many enduser device this 3502i can support at a time.

Thanks,

hari

Nicolas Darchis Mon, 04/25/2011 - 23:16

" This  event lasts through January 14, 2011"

Please open your separate question for that instead of unburying an old event.

thanks.

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