vWLC flexconnect central switched client DHCP issues

[twhittle1]

Hi All,

I'm trying to learn about Cisco Wireless, building a lab at home, and I've hit what I think is a very basic hurdle.

I've deployed a vWLC, connected to a C3560 switch with a couple of APs hanging off.

The vWLC only supports Flexconnect mode so both the APs are deployed in this mode. I'm using WPA2 PSK for basic initial Wireless and Mobility, vwlc, dhcp, labtesting.

When the WLANs are configured with "flexconnect local switching" enabled the clients authenticate and get an ip address in the correct VLAN and it works fine. When I disable local switching the clients don't seem to get an IP address. The clients are associating (according to the monitor > clients, page) but the IP address is showing 0.0.0.0

The vWLC is trunked to the switch. The switch is acting as the DHCP server for the clients. I don't have DHCP relay configured on the switch because I don't think it's needed? DHCP proxy is currently enabled on the WLC. 

I imagine I'm missing something really basic, can anyone shed any ideas?

Many Thanks,

Tom

[Haydn Andrews · Accepted solution]

the vWLC only supports WLANs in local switching mode and the APs in flexconnect mode.

Features not supported on the vWLC:

FlexConnect Central Switching

https://www.cisco.com/c/en/us/td/docs/wireless/technology/mesh/8-2/b_Virtual_Wireless_LAN_Controller_Deployment_Guide_8-2.html

When you turn off flexconnect local switching you are trying to enable Flexconnect Central Switching.

The clients will associate but wont be able to get an IP address if you disable local switching.

Traffic flow is AP Management via CAPWAP to vWLC.

Client traffic needs to drop off locally to the switch so client DHCP is from the wired network so need to ensure DHCP for the client VLAN is available (locally or via helper address).

[twhittle1]

Hi,

Many Thanks for your response, and for replying so quickly!

I had a look around and I was under the impression Cisco changed the central switching support from version 8.2.

When I look in the release notes, version 8.0 says:

• FlexConnect central switching

---

Note FlexConnect local switching is supported.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn80mr5.html#pgfId-1163048

However version 8.2 onwards says:

• FlexConnect central switching in large-scale deployments

NoteFlexConnect central switching is supported in only small-scale deployments, wherein the total traffic on Cisco WLC ports is not more than 500 Mbps.

FlexConnect local switching is supported.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn82mr7.html

My environment is very small, in fact, the interface on the vWLC is physically only 10/100 so below the 500Mbps limit.

I'm wondering if there is something specific I need to do to tell the vWLC to work in this limited 500Mbps mode and enable central switching.

Unless I'm misreading something? Which is very possible :)

Many Thanks,

Tom

[Scott Fella]

Are you sure about this?

vWLC is physically only 10/100

Is you look at the show port summary, does the vWLC port show 1gig?

What is the speed when you do local switching and why would you not use local switching if your VM is 10/100 connected? Is the AP’s on gig or also 10/100?

[twhittle1]

Hi,

Thanks for the below.

That's an interesting point, I bet the vNIC is 1Gbps, I think ESXi defaults to 1Gbps, I'll check later when I get back. I wonder if I could find a way of getting the virtual interface to be 100Mbps if central switching would work.

The reason I was looking at central switching is my little lab is L3 between the different "locations" (crude diagram attached) and in order to get good roaming times I believe I need to use central switching. Eventually, I want to to get wireless VoIP phones and see if I can get seamless roaming. When I was messing around with Flexconnect local switching all the APs had to be in different subnets which makes the AP-AP transition time longer seemingly.

Very happy to be told there's a better way if you think there might be :)

Regards,

Tom

[twhittle1]

I've got an update on this. I've had confirmation from Cisco today that central authentication isn't supported on the vWLC. The previous responder was absolutely correct. 

The release notes are misleading, implying it is possible in small environments:

FlexConnect central switching in large-scale deployments

Note	FlexConnect central switching is supported in only small-scale deployments, wherein the total traffic on Cisco WLC ports is not more than 500 Mbps. FlexConnect local switching is supported.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn85mr3.html#wlc-vwlc

Thanks to all who commented, I just wanted to close the loop.

Regards,

Tom