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Wireless Network Design

Configuring Wireless Cisco Networks and Wireless Controllers.

Wireless Network Design

Postby Guest » Sun Dec 26, 2010 4:03 am


I am looking for some assistance in designing a wireless solution for a customer of ours. A basic diagram of the network is attached. There are actually many more sites than are shown here but I just wanted to keep it simple.

The plan is to have one 1240AG access point at each remote site connected to the WLC across the WAN. The WCS will in time be managed by a WCS server.

Each site is already partitioned into 2 subnets and it is not possible to add a new one for the AP and it's clients.  There will anyway be very little wireless traffic. The AP will operate in H-REAP mode but there will be no local communication required. All traffic is always destined for HQ (ie they use Citrix). Therefore do these APs actually need to be locally switched H-REAPs? If not then how would this work? Can a remote site AP work as a non H-REAP?

Some sites have their own 3560 switch and others have just a switch module inside a 2801 router.

There is no need to have VLANs routed across the WAN.

DHCP is provided by the router on each remote site.

I really need some advice on the best way to implement this solution including but not limited to:

Do I need to have a separate WLAN for each site?

Will DHCP from the router actually work?

How should the switch ports on the HWIC module be configured?

What benefits is there in having a WCS when there is just a single WLC? (I thought WCS was for managing multiple WLC).

I have skimmed the design guides and i am still unclear on the best way to do this.

Any help would be much appreciated






Re:Wireless Network Design

Postby Guest » Sun Dec 26, 2010 4:05 am

You can have a remote site AP in local mode (not H-REAP), but you have to make sure you have enough bandwith for the LWAPP traffic.  You might look at doing H-REAP and do central switching since everything will have to come back.  The switchports the AP's will be connected will have to be trunked.  the AP's management subnet will have to be configured for native vlan.  Since you will be centrally switching, the traffic will be sent from the management subnet back to the WLC.  DHCP will need to be on the HQ side for centrally switched.  Local switched requires DHCP on the remote side. 

Do you need WCS for one WLC.... its really up to you.  Some would say yes and others would say no.  I think this depends on how comfortable you are with the WLC.  With multiple WLC's I would say yes, since I like using the templates.

You should look at the current bandwidth you have at each remote site and see if it meet the requirement for local mode or H-REAP.

Hope this doesn't confuse you.


Re:Wireless Network Design

Postby Guest » Sun Dec 26, 2010 4:17 am

Thanks for the information Fella.

There are just a few bits Im not sure about...

Why would one want to have a H-REAP in central switching mode? It seems to defeat the purpose of H-REAP.

At all sites they use VLAN 10 for data and VLAN 20 for voice. How would I go about configuring the AP for their native VLAN (AP Management Subnet does not exist at remote sites just VLAN 10 - 20? I seem to remember trying to program in VLAN support and WLC requiring a unique native VLAN ID.

What about the WLANs? Do I need a seperate one for each site? If not how will it know which IP address range to give the clients?

Thanks for your patience with this. I'm working hard to get my head around all of this and have been thrown in at the deep end!




Re:Wireless Network Design

Postby Guest » Sun Dec 26, 2010 5:40 am

What vlan is the switch and routers at the remote site on.  You can put the AP's on that vlan.  If you want to do local switching, you will need to map users to a vlan, I guess that would be either vlan 10 or 20.  Usually you would have another subnet for wireless clients, but in your casse you are limited. 

I thought you mentioned you wanted to do central switching since traffic was all going back to HQ?  Just remember, if you do loacl switching, you have to map the ssid to a local vlan.  If you want to do central switching, the vlans have to be created on the HQ side.

It's really up to how you want to design it.  I have clients that have enought bandwidth to run the AP's in local mode, but I have also had clients that didn't have enough bandwidth, but meet the minimum requirement for h-reap.  The good thing with h-reap is that if the ap looses connectivity to the WLC it performs just like an autonomous AP.  The only issues is authentication.  If you do local authentication, users will get authenticated even though the link is down, but users will not able to connect via Citrix.  So since the link back to HQ needs to be up in order for users to connect back, Authentication locally or centrally is up to you.

Remember, that depending on what AP's you use, you can only have 8 - 16 SSID's.  You might want to have scanners on one ssid throught each remote site and laptops or whatever other device on another ssid.

Hope this kind of clears things up.


Re:Wireless Network Design

Postby Guest » Sun Dec 26, 2010 5:43 am

Hi There,

I have read your message and it is making sense now. Thank you very much for that.

I have decided to install it as follows:

1 WLAN to span across all sites (local switching)

Set each AP as H-REAP (Due to not being able to create new VLANs at HQ. I realize that the AP operating indepentently is of no real benefit here)

Map the native VLAN to each AP for each site under H-REAP configuration.

Hope that the wireless clients will pickup DHCP address from the remote routers!

The only thing now is that I am wondering what I should use as the interface for this 'global' WLAN and the DHCP server address for the WLAN.

This is making me think that I will need a seperate WLAN/interface/DHCP server for each site. 8-16 WLANs will not be enough for this customer if this is the case. The APs are all 1242AG.






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