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Ask the Expert: Cisco Wireless LAN Controllers (WLCs)

ciscomoderator
Community Manager
Community Manager

Read the biowith Cisco Expert Nicolas Darchis

Welcome to the Cisco Support Community Ask the Expert conversation. This is an opportunity to learn and ask questions about how to trobuleshoot, configure and deploy any Cisco Wireless LAN controller with Cisco subject matter expert Nicolas Darchis.

Nicolas Darchis 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 since 2007. He also focuses on filing technical and documentation bugs. Nicolas Darchis 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 number 25344.

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

Nicolas might not be able to answer each question due to the volume expected during this event. Remember that you can continue the conversation on the Wireless sub-community, Getting Started with Wireless discussion forum shortly after the event.

This event last through Friday June 28, 2013. Visit the community often to view responses to youe questions of other community members.

146 Replies 146

huangedmc
Level 3
Level 3

hi Nicolas,

Can Flex7500 WLC's support central-switched WLAN's, or are they restricted to local-switched WLAN's only?

We have a bunch of WiSM1 & WiSM2 blades in our datacneter, and 6 WLAN's on FlexConnect/HREAP WAP's in each of the remote campuses.

Two of the WLAN's are central-switched, and support our guest wireless solution, while the other four are local-switched, and support local traffic.

We'd like to replace the WiSM1's w/ Flex 7500.

Will we be able to support our existing WLAN's on 7500, or will we need to get WiSM2, or 8500 to do it?

============

Also, the CAPWAP AP's operate in local-mode by default, when they're out of a box.

Will they join the Flex 7500 in local-mode?

Assuming they can join the 7500, what happens if we don't change them to FlexConnect mode? Will traffic still be forwarded?

I suppose this is related to the first question above.

It looks like the Flex7500 is much cheaper than WiSM2 & 8500, but we'd like to know exactly what caveats are there, so that we don't run in to surprises.

I've consulted data sheets, and "Flex 7500 Wireless Branch Controller Deployment Guide" on Cisco.com, but am still not clear on what the caveats are.

If you could please clarify I'd really appreciate it.

thx

Kevin

Hi Kevin,

the 7500 can support local mode APs yes and can also support centrally switched WLANs. However it has a limited throughput. It does not dedicate the 10Gbps of its ethernet port to centrally switched traffic.

The idea is that the 7500 should be loaded with much more APs than a Wism WLC but on the other hand, they have to be Flex with locally switched WLANs.

It does tolerate a bit of centrally switched traffic but its architecture is not optimized for it.

Regards,

Nicolas

Recorrecting my words after a verification. The 7500 WLC will autoconvert local mode APs to HREAP, so it does not support local mode APs per se. The centrally switched WLAN max throughput is 250Mbps.

Nicolas,

Thank you for the prompt response & clarification.

Is there a hard limit on how many central-switched WLAN's I can have on the Flex 7500?

We're ok w/ limited throughput, as the central-switched SSID's are used by guests only...at least for now.

Could you please point me to a URL, where it references the 250Mbps max throughput?

Not doubting what you're saying, just wanted to know where to look up the info.

If it's not available on a public page, could you at least let me know the name of the file, or the internal link, so that I can have our account team retrieve it?

Also, is the 250Mbps cap per central-switched WLAN, or the aggregate per Flex 7500?

thanks,

Kevin

Hi Kevin,

I'll be totally honest. I found this only in the "New Product Introduction" training for TAC. By the way, checking deeper, 250Mbps of max throughput for centrally switched was for 7.0 release. As of 7.2, it was increased to 1Gbps.

I strongly agree that this should be mentioned in the data sheet, so I will contact the marketing team to have this added. I haven't found another place where it is mentionned.

This throughput is for all centrally switched WLANS combined no matter how many you have

klkilloren
Level 1
Level 1

Nicolas,

I have a RV802 router, recently when I try to connect to my wifi it reads " not in range". I have tried unplugging the router and plugging it back in, but it is still reading the same thing. Can you please help me in troubleshooting this issue. (note: the router is within 10 ft of me)

Hi Katie, unfortunately "linksys routers" does not fit into the subject of this event which is "Cisco Wireless LAN controllers".

However,I would advise checking if you configure an SSID to be enabled, to be broadcasted (if not broadcast, it will be harder to see it). Try to configure no security on it, at least for testing.

I am not sure if that router models requires external antenna. If so, you need to make sure they are plugged in and screwed in correclty

Hi Katie, the RV082 is a Cisco router. The older ones might be branded Linksys. However it does not a WiFi AP built in. Cisco's entry level routers including WiFi would have a 'W" in the name, like RV220W or RV120W.

Best Jo

Product Manager, Enterprise Networking Group

jino_jacob
Level 1
Level 1

Hi Nicholas,

This question is regarding the Clean Air functionality.

We have a mixed environment with Clean Air and Non Clean Air APs that share the same coverage area.

On some controllers we have both types of APs but are part of different coverage areas.

I have read it is not advisable to enable Clean Air with Event driver RRM in a mixed environment but with the enhancements to Clean Air, AP Groups and RF profiles, as part of the WLC firmware release 7.2, is it now possible to enable Clean Air with EDDRM functionality in the above described scenario?

Thanks

Jino

Hi Nicholas,

I'm new to Cisco Wifi infrastructure and don't have much experience.

Recently we have deployed 1 x 2504 WLC with 14 x 3600 APs, all the access points are configured as Flexconnect mode.

Generally, the Wifi is running well, but we had a few clients machine keeps on getting 14Mbps not 144 Mbps. As soon as they disconnect from the Wifi and reconnect, it works fine. They are running Win7 Enterprise x64 and using Win Wifi not IntelProSet.

Can you please point me to a right direction to fix the problem?

Thanks,

Yan

Hi Lap,

it could virtually be anything. But I would tend to think that it's your client that is misbehaving and not roaming properly.

What I suggest you do is when the problem is occuring, go with another laptop to the WLC configuration web page.

Go to Monitor->clients and find the mac address of the problematic client. Click on it to display the details.

Check the signal strength (RSSI) it is displaying. If it is a number below (i.e. further from zero) -70, then indeed, the client is associated to a far away AP and thus having a bad data rate. ( you can also check if the AP name mentioned is physically closeby or not).

Roaming is decided by the client and typically the intel proset is a much better software than the windows native supplicant.

Hi Jino,

yes you can enable it. Indeed the RRM algorithm was improved to evalute potential changes and prevent any cascading effects.

Of course the result will not be as good as if all APs were cleanair (so you might have cases where the APs do not adapt when they should theoretically have), but overall, it shouldn't be any major problem

Hello Nicolas, I have 4 WLC 5508's with many AP's associated to them. One WLC represents one building (4 of them within walking distance), although they are in the same data center at the moment. (on 7.4.100)

I also have 3 ACS servers (5.4) that are configured. I have set up a Corporate Wireless SSID for staff to connect to.... The authentication WPA2 AES + 802.1x where the Laptop's get authenticated by ACS and then the user themselves get authenticated.

The problem I am experiencing is when users go to another building with their laptops, they are not able to authenticate to the SSID, they have to do a full reboot of the laptop to connect cleanly again.

I suspect that one WLC is doing authentication to one ACS, and the other WLC is authenticating to the other ACS.

The result is, when user leaves the building and associates with the SSID, result is the laptop is only authenticating the user, and not the laptop itself because it has already authenticated the laptop. When auth happens with the other ACS it is expecting the auth of the laptop but only gets the user auth.

Is there any way where I can strictly configure priority on authentication servers and make the roaming experience better?

Thank you

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Please rate useful posts & remember to mark any solved questions as answered. Thank you.
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