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Do I need WDS?


I've inherited a University Wireless LAN currently consisting of 50 Cisco APs(VxWorks 350s and IOS 1200s) on a seperate wireless subnet and vlan. Network access is restricted to internet access only.

They are not set up currently with WDS, they authenticate MAC Addresses via a dedicated Wireless LAN Radius Server and then require user logon via a BlueSocket box (using the Universities Central User registration Radius Server for userids and passwords).

We are currently looking to increase the number of APs to around the 200 mark and need to implement some form of AP Management.

I'm puzzled over what WDS actually does and whether I need it or not under the above scenario and whether we will need to use it if we introduce a WLSE into the system.

We are not likely to have more than a few hundred users active on the Wireless LAN at any one time.

All help gratefully received.


Hall of Fame Super Red

Re: Do I need WDS?

Hi Jen,

Here is some info to get you started and to possibly help with your decision. It is likely, especially if you are going to deploy WLSE that you will also want WDS devices. I would certainly recommend that you sit down with your local Cisco SE to go over this type of scale increase. You may also want to look at replacing the 350's and/or perhaps going with LWAPP instead;

Configuring WDS, Fast Secure Roaming, and Radio Management

Understanding WDS

When you configure Wireless Domain Services on your network, access points on your wireless LAN use the WDS device (either an access point or a switch configured as the WDS device) to provide fast, secure roaming for client devices and to participate in radio management. If you use a switch as the WDS device, the switch must be equipped with a Wireless LAN Services Module (WLSM). An access point configured as the WDS device supports up to 60 participating access points. A WLSM-equipped switch supports up to 300 participating access points.

Fast, secure roaming provides rapid reauthentication when a client device roams from one access point to another, preventing delays in voice and other time-sensitive applications.

Access points participating in radio management forward information about the radio environment (such as possible rogue access points and client associations and disassociations) to the WDS device. The WDS device aggregates the information and forwards it to a wireless LAN solution engine (WLSE) device on your network.

Role of the WDS Device

The WDS device performs several tasks on your wireless LAN:

Advertises its WDS capability and participates in electing the best WDS device for your wireless LAN. When you configure your wireless LAN for WDS, you set up one device as the main WDS candidate and one or more additional devices as backup WDS candidates. If the main WDS device goes off line, one of the backup WDS devices takes its place.

Authenticates all access points in the subnet and establishes a secure communication channel with each of them.

Collects radio data from access points in the subnet, aggregates the data, and forwards it to the WLSE device on your network.

Registers all client devices in the subnet, establishes session keys for them, and caches their security credentials. When a client roams to another access point, the WDS device forwards the client's security credentials to the new access point.

Participating Access Points Supported by WDS Devices

Access point that also serves client devices


Access point with radio interfaces disabled


WLSM-equipped switch


Role of Access Points Using the WDS Device

The access points on your wireless LAN interact with the WDS device in these activities:

Discover and track the current WDS device and relay WDS advertisements to the wireless LAN.

Authenticate with the WDS device and establish a secure communication channel to the WDS device.

Register associated client devices with the WDS device.

Report radio data to the WDS device.

From this good doc;

Wireless Domain Services Configuration

Wireless Domain Services FAQ

What is WDS and Why Do I Need It?

Hope this helps! Good luck!


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Community Member

Re: Do I need WDS?

Thanks Rob, thats exactly what I needed!

Very helpful.



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