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ASK THE EXPERT- WIRELESS SOLUTIONS

Welcome to the Cisco Networking Professionals Ask the Expert conversation. This is an opportunity to discuss Wireless Solutions with Cisco expert Ann Sun. Ann is currently the Senior Manager of Market Development for the Wireless Networking Business Unit at Cisco Systems and has over eight years of experience in networking technologies. Her work at Cisco Systems is focused on driving the evangelism and technology adoption of Wireless LAN solutions worldwide. Feel free to post any questions relating to Wireless Solutions. Remember to use the rating system to let Ann know if you’ve received an adequate response.

Ann 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 November 8. Visit this forum often to view responses to your questions and the questions of other community members.

58 REPLIES
New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

What are the key differences between deployment of a 2.4 & 5GHz systems?

TIA

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Mounting of access points due to 5GHz attached antennas (FCC regulation) will be different. Slightly reduced range at 5GHz will require more access points. Also note that not all regulatory bodies in various countries have approved the 5GHz spectrum for WLAN deployment.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

What is the best security solution with 350 Series and a ACS? LEAP? LEAP+WEP? Something different?

TIA

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Hello..

The best solution available for WLAN security as of today is 802.1x. Pls have a look at this link for more details:

http://www.cisco.com/en/US/partner/products/hw/switches/ps708/products_configuration_guide_chapter09186a00800da6ff.html

Cisco supports 802.1x on most of the catalyst switches.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

The best security solution is dependent on each company's requirements. You need to perform a risk assessment and security analysis specific to your network. For WLAN networks, recommended best practices include using 802.1x with mutual authentication (e.g. LEAP with ACS), the use of dynamic WEP keys, in addition to the use of per packet keying, Message Integrity Check (MIC) and broadcast key rotation. For more information, please view SAFE: Wireless LAN Security In Depth White Paper at: http://www.cisco.com/en/US/netsol/ns110/ns129/ns131/ns128/networking_solutions_implementation_white_paper09186a008009c8b3.shtml

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

i'm using 340 series bridge for a point to point connection in order to transfer files from a pc to another , is it possible that the maximum real date rate for the payload is 4.5Mb/s at a distance of 10 cm??

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Assuming you are using 802.11b technology, the maximum data rate is 11Mbps. However, 802.11 is shared media, so the actual throughputs that you see are always less than that (you will never actually hit 11Mbps). 4.5Mbps does not sound unreasonable, but there are many variable factors such as interference, PC performance, packet sizes, antennas, transmit power settings, etc. that affect your data rates.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Using the technology 802.11b which is the data rate rate for the data payload ever seen ???

I'va another question:

I' m using two wireless bridge to transfer a folder from a pc to another.

supposig that i would like to transfer from the station A to the station B, if the command starting copy is given from A the data rate is half of that reached if the command starting copy is given from B. The same thing happens transfering from B to A.

Thanks

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

I am final year Postgraduate Student at University of Technology Sydney, Australia.

So I'm doing a research about the Wireless Security.

My question is :

What is the best security solution you may over WLAN and Wireless over the internet?? and if your marketing/sales departments in your company based on Wireless LAN and Internet/intranet what is the risk analysis they may face? If what is Policy and procedure you recomend?? If they don't have any problem what technology do you recomend??

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Please forgive me but I am having troubling understanding your questions. As I replied in a previous post about the best security solution, this is entirely dependent on an individual company's requirements and an internal security assessment. I detailed some best practice guidance, along with the URL for WLAN Security In Depth White Paper at:

http://www.cisco.com/en/US/netsol/ns110/ns129/ns131/ns128/networking_solutions_implementation_white_paper09186a008009c8b3.shtml

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

I have two Aironet 340 Point Access and I want connect two wired LAN that are in different buildings.

I have configurated:

-> 1 acces point / root

-> 1 client / non-root

The "association menu" say:

The client is associated with the access point, but the menu doesn´t say that the access point is associated with anyone.

I can ping between aironet but I can not ping between PCs.

What´s happend? How have I to form?

Thanks

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

You are looking for bridging function. Access Points does not give bridging function.

AP supports a repeter mode to extend the radio for remote radio clients. In repeter mode an AP can associate to an other AP, and do relay for WLAN clients. In repeter mode the ethernet interface is shutdown.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

If I connect a Bridge and a Access Point (as root), can I transmit from AP´s ethernet to Bridge´s ethernet?

Because I do not want to use two bridges.

Thanks

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Ms. Sun:

I am also doing some school related research on Wireless. Can you tell me the area that can be covered by a wireless hub that is mounted outdoors and by a hub that is mounted indoors? I'm sure the answer to this question depends on a number of factors. But can you give me an idea of how much it might cost to provide wireless Ethernet access in a town square, an airport terminal, a stadium, and a shopping mall? I am trying to find out how much it would cost to provide Wireless Ethernet coverage in these environments.

Thank you,

Scott Knight

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Scott - you are absolutely correct in stating the answer is dependent on a number of factors. Indoor WLAN using APs and outdoor bridging are quite different scenarios, with different power output levels available on the radios (as well as differences in .11b vs .11a technologies). Different antenna options exist for both indoor & outdoor usage, which change the coverage in many different ways (e.g. an omnidirectional vs. directional antenna as well as the gain of the antenna). There really is no easy way to "estimate" the cost of providing WLAN coverage for either indoor or outdoor usage unless you actually do a site survey with the equipment you plan to use.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Hi

I have a remote site linked to my main building using a 100Mb infra red laser. I can trunk my VLAN s over this link with no trouble.

I want to install a wireless link to act as backup incase the laser fails. I cannot seem to find any solution that allows VLAN trunking over a wireless link. Is this possible to do?

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

You are lucky ! We have just release the Bridge 350 version that support up to 16 VLANs.

You can associate a 802.1Q tag with an SSID and then support WLAN VLAN.

http://www.cisco.com/en/US/products/hw/wireless/ps458/prod_release_note09186a0080102550.html

Vincent

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Will this feature be available for 350 series bridges as well as 350 access points.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Does AP 1200, AP 350 support EAP-SIM based authentication.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Yes, both the AP1200 and the AP350 support EAP-SIM based authentication. On the client side, ACU v 5.05.001 is required.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

New Cisco 1100 Access Point

The data sheet on this product says -

"The Cisco Aironet 1100 Series features a single, upgradable 802.11b radio, integrated diversity dipole antennas, and an innovative mounting system for easy installation in a variety of locations and orientations."

Am I right in thinking that, as with the 1200, the upgrade this sentence speaks of is a hardware only upgrade?

Thanks

Keith

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Keith - for the 802.11b radio upgrade, it would indeed be a hardware upgrade by replacing the radio module (not the entire unit). You're probably already familiar with using the Wireless Software Center for software upgrades to the products.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

I have a question regarding the RF impairment performance of the Aironet 350 access point and how the AP responds to both co and adjacent channel interference.

In our WLAN operating environment, other possibly unrelated users may from time to time set up foreign 802.11B devices, either on our channels or on other channels that partially overlap the channels we are operating on.

We’ve observed 802.11B devices from other manufacturers, operating up to several channels removed from one of our Aironet 350 devices, causing interference into the Aironet device channel. That was expected. However, while attempting to quantify the impairment conditions, it was noted that if another 350 where to be operating on the same adjacent channel, it does not appear to cause the same level of interference. Is there an active mechanism at work here, and can it be user configured?

In our operating environment, we need to be able to better predict interference from other 802.11B devices, and in some cases take advantage of known interference levels to enhance varied security issues.

All bets are off with other non WLAN devices such as 2.4 GHz cordless phones or X10 type video cameras, but I'm only concerned with 802.11B equipment.

Thanks

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

The difference in level of interference you are seeing between another vendor's AP compared to Cisco's AP350 when both are operating on overlapping channels to the existing WLAN network are most likely due to different transmitter characteristics. The transmitter may not have more than a certain level of RF energy in the adjacent channels, and the likely scenario is the filtering in the transmitter of the Cisco AP is better. There is nothing that can be user configured to change this.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

It seems like everyone is giving up on cabling for SOHO LANs, in favor of 802.11b WLANs. With so many people plunking down Access Points, and running them at maximum transmission power (under the "more is better" philosophy) I'm concerned that overlap is going to become a serious problem in high density areas like apartment blocks and office buildings.

Q. 1) Is this a legitimate concern ?

Q. 2) What RF statistics would help identify interference from neighboring office access points ?

Q. 3) If neighboring office APs were close enough together, would they be subject to delays introduced by the collision avoidance mechanisms.

Q. 4) If collision avoidance was causing a significant slowdown in traffic, what statistics would help identify the problem ?

Thank you.

--------------------------------------------------------------------------------------------------------

An excerpt from Cisco's Aironet 1200 documentation:

"...overlapping coverage areas on the same frequency detect adjacent cell traffic and delay transmissions that would cause collisions. This configuration reduces the aggregate radio system throughput. Heavy cell overlap is not recommended for maximum system throughput."

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

You bring up an important point about deployment of 802.11 networks, which is that a site survey needs to be done to optimize the WLAN coverage and minimize bleed through outside a building or to other floors.

1) This is a concern if in a high density area, the people deploying WLANs are not careful in their network design considerations. By doing a site survey, one can see where the transmit power may need to be tuned down,what channels to use where (preferably non-overlapping channels -1, 6, 11 for 802.11b), and ensure proper AP placement.

2) Utilizing a wireless analyzer tool (e.g. AirMagnet ) allows you to see the various APs in the area, the channel they are on, the security mechanisms used, etc. and could be used to identify those APs which are not part of your network.

3) It would be rare to find a situation where the APs (from a neighbor network) overlap so much that you could see significant delay, although it is possible.

4) Again, as in Q2, using a wireless analyzer allows you to identify all the APs in the area, you can actually pinpoint their locations by doing a walk around, and then find your neighbor to discuss how to better manage the situation.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

We have three airnet340 that the cat5 provide power from the connection to a switch cisco1924. The user looses network connectivity occassionly.

Is the cisco 1924 causing this airnet connection to hang because it does not have enough power to support this airnet? Or does it hang up this ports when creates to many colusions?

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

I'm not clear on your question as the AP340s do not support inline ethernet power, nor does the 1924 switch, so you must be providing power to the APs via local power supply? In any case, the power supply is independent of client to AP wireless connectivity. Typically what happens when a client experiences loss of connectivity is that the AP coverage pattern has some gaps between cells such that when the user is moving around, they may fall into a "dead zone" where the gap is.

New Member

Re: ASK THE EXPERT- WIRELESS SOLUTIONS

Is there a good book that I could reference that has up to date information on 802.11?

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