Cisco Systems 69561 User Manual

Wireless LAN Controller (WLC) FAQ

Document ID: 69561

Questions

Introduction
General FAQ
Troubleshoot FAQ
NetPro Discussion Forums − Featured Conversations
Related Information

Introduction

This document provides information on the most frequently asked questions (FAQ) about the Cisco Wireless
LAN (WLAN) Controllers (WLCs).

Refer to Cisco Technical Tips Conventions for more information on document conventions.

General FAQ

Q. Where can I find more information about the installation of WLCs in
my WLAN network?

A. Refer to these documents:

Cisco Wireless LAN Controller Module Q&A♦
Cisco Wireless LAN Controllers Q&A♦

Q. How do I find the version of code that runs on the WLC from the GUI?

A. From the Wireless LAN Controller GUI, click Monitor > Summary. In the Summary
page, the Software Version field shows the version of firmware that runs on the Wireless
LAN Controller.

In order to find the version of firmware that runs on the WLC through the WLC CLI, use the
command show run−config.

(Cisco Controller) >show run−config

Press Enter to continue...

System Inventory

Burned−in MAC Address............................ 00:0B:85:33:52:80

Press Enter to continue Or <Ctl Z> to abort

System Information

Manufacturer's Name.............................. Cisco Systems Inc.

Product Name..................................... Cisco Controller

Product Version.................................. 4.0.217.0

RTOS Version..................................... 4.0.217.0

Bootloader Version............................... 4.0.217.0

Build Type....................................... DATA + WPS

Compact Flash Size............................... 256 MB

In order to view the active boot image, use the command show boot

(Cisco Controller) >show boot

Primary Boot Image............................... 4.0.217.0 (active)

Backup Boot Image................................ 4.0.155.5

Q. What is the procedure to upgrade the operating system (OS) software
on a Cisco WLC?

A. The Wireless LAN Controller (WLC) Software Upgrade to Versions 3.2, 4.0, and 4.1
document provides the procedure for a software upgrade on your WLC.

Q. Can I upgrade directly from Version 3.1.105 to Version 3.2.78, or do I
need to upgrade to Version 3.1.111 before I upgrade to Version 3.2.78?

A. Yes, you can upgrade directly to 3.2.78.0 from 3.1.105.0. After you set up a TFTP server,
you can choose Commands > Download File, and then choose Code from the File Type
menu to download the software to the WLC. Reboot the WLC after the file transfer for the
new code to take effect.

For instructions on how to perform the upgrade, refer to Wireless LAN Controller (WLC)
Software Upgrade to Versions 3.2, 4.0, and 4.1.

Q. Can an Airespace controller that runs Code Version 3.2 be upgraded
to Controller Version 4.0? If so, can it be directly upgraded or does it
have to be upgraded in increments?

A. All Airespace controllers run up to 3.2 code. Only the Cisco Controllers can run 4.0 and
later.

Q. Does the 4400 WLC route the VLANs that are configured on it like a
router?

A. The 4400 WLC is an appliance that attaches to your network but does not function like a
router. There should be a Layer 2 or Layer 3 device to provide the routing for the VLANs.
The WLC maps the SSID of the clients to the VLAN subnet and puts them back out the
management interface for the upstream routers to distribute/ACL, etc.

Q. What happens to the wireless network when I perform a software
upgrade? Do all the access points (APs) go down until they are
upgraded, or are they upgraded one at a time so that the wireless
network can remain up (except for the specific APs that undergo the
upgrade)?

A. The upgrade is done on the WLC, as well as on all the lightweight APs (LAPs).

Note: A LAP always has the same version as the WLC.

You must reboot the WLC in order for the new software to take effect, so there is a period of
network downtime. Be sure to schedule a maintenance window for the upgrade.

Q. Can a Cisco IOS Software−based access point (AP) that has been
converted to lightweight mode register with Cisco 4100 Series WLCs?

A. No, Cisco IOS Software−based APs that are converted to lightweight mode cannot register
with the Cisco 40xx, 41xx, or 3500 WLCs. These lightweight APs (LAPs) can register only
with the Cisco 4400 and the 2000 series WLCs. For information on the restrictions of APs
that are converted to lightweight mode, refer to the Restrictions section of Upgrading
Autonomous Cisco Aironet Access Points to Lightweight Mode.

Q. What is the maximum number of APs supported on the 4402 and 4404
Wireless LAN Controllers (WLCs)?

A. The limitation on the number of supported access points is based on the hardware that you
have. The 4402 WLC with two gigabit Ethernet ports comes in configurations that support 12,
25, and 50 access points. The 4404 WLC with four gigabit Ethernet ports supports 100 access
points.

Q. How do I configure a local database on the Wireless LAN Controller
(WLC)? What are the special characters that can be used for the local net
user username and passwords?.

A. The local user database stores the credentials (username and password) of all the local
network users. These credentials are then used to authenticate the users. You can configure
local network users through either the GUI or the CLI. You can enter up to 24 alphanumeric
characters. All the special characters with the exception of the quote character can be used for
the username and passwords.

From the CLI, use these commands to create a local net use:.

config netuser add <username> <password> wlan <wlan_id> userType

♦

permanent description <description> Adds a permanent user to the local user
database on the controller.

config netuser add <username> <password> {wlan | guestlan} {wlan_id |

♦

guest_lan_id} userType guest lifetime seconds description <description>Adds a
guest user on a WLAN or wired guest LAN to the local user database on the
controller.

From the GUI, you can configure local net users from the Security > AAA > Local Net
Users page.

Q. Is it possible to automatically delete the local net user on the
controller?

A. You can give the local net user configured on the controller a lifetime which automatically
deletes the username after the allotted lifetime.

Q. How many WLCs can I have in the same mobility group?

A. You can place up to 24 regular WLCs (Cisco 2000, 4100, and 4400 series) in a single

mobility group. You can configure up to 12 Wireless Services Module (WiSM) blades in one
mobility group. Therefore, up to a maximum of 3600 access points (APs) are supported in a
single mobility group.

Q. How does DHCP work with the WLC?

A. The WLC acts as a DHCP relay device. The WLC does the DHCP relay through the
virtual interface. Typically, the 1.1.1.1 address is assigned to the virtual interface. This
address can be any address. However, it must not be a routable address.

These are the events that occur:

The WLAN client sees the administration−defined virtual address as the DHCP

1.
server address. The recommended address is usually 1.1.1.1 because this address is
not normally a routable network address.
The WLC shows the virtual address to the WLAN clients and the management

2.
interface address upstream.
The WLC acts as a DHCP relay (Bootstrap Protocol [BOOTP] relay) device.3.

Note: When the internal DHCP server is used, the lightweight access point (AP) should be
directly connected to the WLC. Also, you cannot share a DHCP scope between two or more
WLCs.

Q. Does the Cisco 4400 Series WLC support Internetwork Packet
Exchange (IPX) protocol? Does any Airespace product support IPX
protocol?

A. No, IPX protocol is not supported on any platforms of the Cisco WLC.

Q. What are the prerequisites to access the graphical user interface
(GUI) of the Wireless LAN Controller (WLC)?

A. The controller GUI requires this operating system and web browser:

Windows XP Service Pack 1 (SP1) or later, or Windows 2000 SP4 or later♦
Internet Explorer 6.0 SP1 or later

♦

Note: Internet Explorer 6.0 SP1 or later is the only browser supported to access the
controller GUI and to use WebAuth.

Q. Is the Wireless LAN Controller (WLC) GUI supported on Mozilla
browsers?

A. No, WLC GUI is not supported on Mozilla browsers.

Q. How do I retrieve Cisco Wireless LAN Controller (WLC) MIBs on the
web?

A. You can download the Cisco WLC MIBs from the Wireless Downloads (

only

) page.

Complete these steps in order to download the WLC MIBs:

registered customers

From the Wireless Downloads page, click on Wireless LAN Controller and select

1.
the controller platform for which you need the MIBs.
The Software Download page for the controller appears. This page contains all the

2.
files for the WLC including the MIBs.
Download the standard MIBs and the Cisco specific MIBs. These two files should be

3.
downloaded and contain the MIBs. The filenames look similar to this example:

Standard−MIBS−Cisco−WLC4400−2000−XXXXXX.zip

Cisco−WLC−MIBS−XXXX.zip

Q. Can a controller push configurations to other controllers and manage
them, without a wireless control system (WCS)?

A. No, controllers do not have the ability to push configurations to other controllers or
manage them.

Q. In a WLC version 4.0, what is the maximum number of supported
controllers per mobility group and per radio frequency (RF) domain?
Also, in guest tunneling, how many Ethernet over IP (EoIP) tunnels can
be formed between a single anchor controller to different internal
controllers?

A. The latest WLCs support up to 20 WLCs per RF domain and 24 WLCs per mobility group.
Also, a single anchor controller supports up to 40 EoIP tunnels with one tunnel per internal
WLC. These WLCs can be of different mobility groups.

Q. What are the functional differences between the 2000 Series
Controllers and the 4400 Controllers?

A. The major differences between the 2000 and 4400 Series Controllers are in the features
they support.

A 2000 Series Controller does not support these hardware features:

Power over Ethernet (PoE)♦
Service port (separate out−of−band management 10/100−Mbps Ethernet interface)♦

These software features are not supported on 2000 Series Controllers:

VPN termination (such as IPSec and L2TP)♦
Fortress♦
External web authentication web server list♦
Layer 2 LWAPP♦
Spanning tree♦
Port mirroring♦
AppleTalk♦
IPv6 pass−through♦

A 4400 Series Controller supports all the forementioned hardware and software features.

Q. Which lightweight access points (LAPs) do the 4100 Series
Controllers support?

A. Only the Airespace 1200, 1250, the Cisco 1000 Series, and the Cisco 1500 Series LAPs
work with the earlier 4100 Series Controllers.

Q. I have a Cisco Adaptive Security Appliance (ASA) device. Can I use
this ASA as a DHCP server instead of windows DHCP server in order to
assign IP addresses to my lightweight access points (LAPs)?

A. No, it is not possible to use an ASA as a DHCP server for LAPs. This is because the
DHCP requests from the LAPs are forwarded to the external DHCP server through the WLC.
Therefore, a WLC acts as a DHCP relay agent to forward the request from the LAP.
However, ASA does not support DHCP requests from a DHCP relay agent.

If ASA is configured as a DHCP server, you cannot configure DHCP relay services on an
interface on which the server is enabled. Additionally, DHCP clients must be directly
connected to the interface on which the server is enabled. Refer to PIX/ASA as a DHCP
Server and Client Configuration Example for more information.

The Cisco ASA combines the functions of a firewall, Virtual Private Network (VPN), and
intrusion prevention system (IPS) in a single appliance. The ASA is managed by an
easy−to−use Adaptive Security Device Manager (ASDM).

Q. Is it possible to go back and make corrections in the wireless LAN
controller (WLC) configuration wizard at the time of the initial
configuration?

A. Yes, this can be done with the − (hyphen) key. Use this key to re−enter the previous
parameter value.

For example, you use the WLC configuration wizard in order to configure the WLC from
scratch.

Instead of entering the username as admin, you enter it as adminn. In order to correct this,
enter − (hyphen key) at the next prompt, then click Enter. The system returns to the previous
parameter.

(Cisco Controller)

Welcome to the Cisco Wizard Configuration Tool
Use the '−' character to backup
System Name [Cisco_e8:38:c0]: adminn
Enter Administrative User Name (24 characters max): −

System Name [Cisco_e8:38:c0] (31 characters max):

Q. In accordance to RFC 1907 for Simple Network Management Protocol
(SNMP), the SNMP location field should support a size from 1−255.
However, I am unable to enter more than 31 characters in the SNMP
location field. Why?