Clients disconnect on LAP vWLC

[John Peterson]

Hi,

We have deployed an virtual wireless controller in our network with four APs.

From time to time we have noticed some clients keep dropping off the network and then re-connecting. I have looked at the logs of the AP and I'm seeing logs of Rouge AP which are found in our area, which are legitimate AP from other business.

When trying to log into the controller at some points the controller is unreachable, even via pings and then it would respond. I then came to the conclusionthat as the vWLC is not available, clients are not able to connect and enabled local switching, but still has not resloved the issue.

The vWLC only supports Flexconnect, if we have multiple vlans and configure local switching should we be also mapping the VLANs to the SSID under each AP?

Thanks.

[Scott Fella]

When using local switching, you must map the WLAN to the appropriate vlan on each AP. this means that the AP has to be on a trunk port in which its management IP is defined as the native vlan and them you can apply the WLAN to vlan mappings.

I would also maybe look at the VM itself as to why it becomes unavailable. . When this happens, check to make sure the VM is running as maybe ESXi is performing some task at the time. Also make sure that the requirements are there for the VM itself when it comes down to hardware, CPU, virtual cores, memory and hard drive.

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[John Peterson]

Thanks,

We are not using local switching at the moment, but as the vwlc only supports flexconnect I think we need to configure local switching which may help the clients to stay on the wireless. Would you agree?

In terms if VMware resource, should we be setting reservation on the vm it self?



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[Scott Fella]

I was explaining what you need to perform when you do local switching. It's best to do that if your vWLC isn't stable. As far as the requirements for the VM, look at the release notes for the ova that you used when installing the vWLC. That will tell you how many virtual cores, memory and hard drive space you need.

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[Scott Fella]

Central switching which you have now is the same if you had a WLC and the AP's were in local mode. When using FlexConnect, its almost better to locally switch the traffic if possible. Guest is usually the only thing I would centrally switch and again, it depends on the design. Locally switch in your case is probably the best way to go.

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[Scott Fella]

Also make sure the the VM is setup in promiscuous mode. Double check to make sure the VM is setup properly.

http://www.cisco.com/en/US/products/ps12723/products_tech_note09186a0080bd2d04.shtml#definition

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[John Peterson]

Ahh makes sense, to obtain the full Flexconnect feature local switching has to be enabled. Cisco didn't explain this in the deployment guide. 

In terms of Guest we have two networks both of which terminate at the Edge with the firewall and is on a separate vlan (ssid). What would be the benefits of centrally switching this when compared to local switching, would it be because of ACL. Sorry I'm getting started into the wireless world.

I have seen the Guest SSID option when creating SSID does this provide a tunnel like system which isolated the traffic?

I have double checked the VM setting, in our case management is on the same vlan as one of the SSID and the only port connecting to the outside network is in promiscuous mode. (I learnt this after hours or troubleshooting)

The vWLC does not have a internal DHCP server, this is provided by a Windows 2008 machine. Its all working apart from the above is there any setting which I need to change for this DHCP design?

John.

[Scott Fella]

Well the reason you would tunnel back guest or centrally switch is so that you only have one spot for an ACL or else if you locally switch the guest, you need to have an ACL for each location.

As far as locally switch or centrally switch, it depends on what you want to do. Preferably, most will locally switch, but others prefer to centrally switch especially if they have huge wan pipes.

When locally switch, the traffic is placed local at the site so you need to have dhcp available for that subnet at the site.

Hope this helps.

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[John Peterson]

Hi Scott,

In relation to the clients dropping off we are seeing a number of Rouge AP alerts from the controller. We have noticed these are neighbouring AP which are within the same building. Could this be causing an issue?

For DHCP to be centrally processed per site, is there any special configuration which needs to be present in the vitual wireless controller?

[Scott Fella]

You have to see what this signal is from those AP's and what is really happening with the clients. Maybe they are connecting to one of the other AP's and this disassociating from yours. Make sure the devices don't have other SSID's in their profile that can cause an issue.

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