AP Placement Campus Network Wism2

[nitramspud]

Hello,

Looking for some advice in relation to our Wireless infrastructure.

Large campus network, approx 50 wiring closets, collapsed-core configuration at present (soon to be migrated to 3-teir).

We have two Wism2's configured in HA connected to the core, with approximately 500 AP's throughout the campus.

There are approx. 200 VLANS throughout the campus, with most access switches configured with their own unique data and voice vlan, together with generally a printing and building management VLAN.

The current wireless configuration has the management IP addresses of every AP in a single VLAN (in this case vlan 50), which is spanned to every access switch. The wism ap-management interface is also a member of vlan50. Management IP addresses of the AP's is via a DHCP helper address to a DHCP server for this VLAN.

I've been reading a number of wireless design documents, but I cannot ascertain what the best practise is in relation to ap placement, in terms of VLAN's. I understand our AP's use CAPWAPP to tunnel back to the wlc, and it is also my understanding that management of the AP's is via routed L3.

I'm trying to minimise vlans that are spanned across multiple access-layer switches, and am therefore questioning the correctness of having VLAN50 spanned across all of our switches, just to support AP management.

I'd love to hear what is the best practise for examples such as this in a large environment - my thoughts were that the AP's should just be connected to an access port (not trunk) on the local VLAN in each closet. However, this would mean that AP's would not be on the same subnet, but would negate the need for VLAN50 to be spanned across the whole campus.

I hope I've explained this sufficiently, and would welcome anybodys thoughts, or indeed any links to any information that helps in this case. 

Many thanks in advance.

[Scott Fella]

If you are going to a L3 design, why not just keep vlan id ap your access point vlan. All that is changing is the subnet information, and AP’s are fine if they are not on the same subnet as the wlc management, but should be in its own subnet which is typical. As long as you have connectivity back to the controller, you can use option 43 or dns to point the AP’s to the controllers management interface. You don’t have to span that subnet everywhere.

[nitramspud]

Scott - thank you for your reply.

So, for example if each access layer closet/location has a voice and data vlan, put the ap into the data vlan in that closet? They will indeed find their way to the controller over L3, and most subnets configured on the campus have option 43 enabled for wireless already.

I hope I'm understanding you rightly - as if so, this is what I was going to do, and then stop spanning the current AP-management VLAN.

Thank you again

SP

[Scott Fella · Accepted solution]

That is correct. You can take any of your AP’s right now that are joined and move them into a different vlan and the ap will find and join the controller. This is as long as the ap in the new subnet has connectivity back to the controller. A joined ap will store the controller information in nvram or if you defined the controller in the ap high availability, this will also help. Option 43 is really for new AP’s that has never joined.

[nitramspud]

thank you again

[Scott Fella]

No problem. Looks like it will be a pretty easy migration. You will just have to plan each phase, but once one phase is done, it should be easy as pie.