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Cisco 4400 Series Wireless LAN Controllers

Wireless LAN Controller and Lightweight Access Point Basic Configuration Example

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Document ID: 69719


Contents

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
Background Information
Configure
      Network Diagram
      Configure the WLC for Basic Operation
      Configure the Switch for the WLC
      Configure the Switch for the APs
Verify
Troubleshoot
      Commands
      Controller Does Not Defend AP-Manager IP Address
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Related Information

Introduction

This document provides a basic configuration example of a lightweight access point (AP) that is connected to a Cisco Wireless LAN (WLAN) Controller (WLC) through a Cisco Catalyst Switch.

Prerequisites

Requirements

Ensure that you meet these requirements before you attempt this configuration:

  • Basic knowledge of the configuration of lightweight APs and Cisco WLCs

  • Basic knowledge of Lightweight AP Protocol (LWAPP)

    Refer to Understanding the Lightweight Access Point Protocol (LWAPP) for more information.

  • Knowledge of the configuration of an external DHCP server and/or domain name server (DNS)

  • Basic configuration knowledge of Cisco switches

Components Used

The information in this document is based on these software and hardware versions:

  • Cisco Aironet 1010 Series Lightweight AP

  • Cisco 4402 Series WLC that runs firmware 3.2.116.21

  • Microsoft Windows Server 2003 Enterprise DHCP server

This configuration works with any other Cisco WLC and any lightweight AP.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Conventions

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

Background Information

If the APs reside in a different subnet than the WLC, you must implement one of these methods in order to allow WLC discovery:

  • Use DHCP with option 43.

  • Use DNS entry CISCO-LWAPP-CONTROLLER.localdomain in order to resolve the management IP address of the WLC.

  • Prime the AP.

The Cisco 1000 Series APs use a string format for DHCP option 43, whereas the Aironet APs use the type, length, value (TLV) format for DHCP option 43. DHCP servers must be programmed to return the option based on the AP DHCP Vendor Class Identifier (VCI) string (DHCP option 60). Table 1 lists the VCI strings for Cisco APs that can operate in lightweight mode.

wlc_lwap_config-0a.gif

1Any 1500 Series AP running 4.1 software

21500 OAP AP running 4.0 software

31505 Model AP running 4.0 software

41510 Model AP running 4.0 software

5Any 1500 Series AP running 3.2 software

The format of the TLV block is:

  • Type—0xf1 (decimal 241)

  • Length—number of controller IP addresses * 4

  • Value—list of WLC management interfaces

You can configure DHCP servers to return WLC IP addresses in vendor-specific option 43 in the DHCP offer to lightweight Cisco APs. When the AP gets an IP address through DHCP, the AP looks for WLC IP addresses in the option 43 field in the DHCP offer. The AP sends a unicast LWAPP discovery message to each of the WLCs that are listed in the DHCP option 43. WLCs that receive the LWAPP discovery request messages unicast a LWAPP discovery response to the AP. The AP attempts to resolve the DNS name CISCO-LWAPP-CONTROLLER.localdomain. When the AP is able to resolve this name to one or more IP addresses, the AP sends a unicast LWAPP discovery message to the resolved IP addresses. Each of the WLCs that receives the LWAPP discovery request message replies with a unicast LWAPP discovery response to the AP.

Configure

Complete these steps in order to register APs:

  1. Have a DHCP server present so that the APs can acquire a network address.

    Note: Option 43 is used if the APs reside in a different subnet.

  2. Configure the WLC for basic operation.

  3. Configure the switch for the WLC.

  4. Configure the switch for the APs.

  5. Register the lightweight APs to the WLCs.

  6. Configure mobility groups for the WLCs.

Note: Use the Command Lookup Tool ( registered customers only) in order to obtain more information on the commands used in this section.

Network Diagram

This document uses this network setup:

wlc_lwap_config-1.gif

Configure the WLC for Basic Operation

When the controller boots at factory defaults, the bootup script runs the configuration wizard, which prompts the installer for initial configuration settings. This procedure describes how to use the configuration wizard on the command-line interface (CLI) in order to enter initial configuration settings.

Note: Be sure that you understand how to configure an external DHCP server and/or DNS.

    Complete these steps in order to configure the WLC for basic operation:

  1. Connect your computer to the WLC with a DB-9 null modem serial cable.

  2. Open a terminal emulator session with these settings:

    • 9600 baud

    • 8 data bits

    • 1 stop bit

    • No parity

    • No hardware flow control

  3. At the prompt, log in to the CLI.

    The default username is admin, and the default password is admin.

  4. If necessary, enter reset system in order to reboot the unit and start the wizard.

  5. At the first wizard prompt, enter a system name. The system name can include up to 32 printable ASCII characters.

  6. Enter an administrator user name and password. The user name and password can include up to 24 printable ASCII characters.

  7. Enter the service-port interface IP configuration protocol, either none or DHCP.

    Enter none if you do not want to use the service port or if you want to assign a static IP address to the service port.

  8. If you entered none in step 7 and need to enter a static IP address for the service port, enter the service-port interface IP address and netmask for the next two prompts.

    If you do not want to use the service port, enter 0.0.0.0 for the IP address and netmask.

  9. Enter values for these options:

    • Management interface IP address

    • Netmask

    • Default router IP address

    • Optional VLAN identifier

      You can use a valid VLAN identifier or 0 for untagged.

    Note: When the management interface on the controller is configured as part of the 'native vlan' on the switchport to which it connects, the controller should NOT tag the frames. Therefore, you must set the VLAN to be zero (on the controller).

  10. Enter the Network Interface (Distribution System) Physical Port number.

    For the WLC, the possible ports are 1 through 4 for a front-panel gigabit Ethernet port.

  11. Enter the IP address of the default DHCP server that supplies IP addresses to clients, the management interface, and the service-port interface, if you use one.

  12. Enter the LWAPP Transport Mode, either LAYER2 or LAYER3.

    Note:  If you configure the WLC 4402 via Wizard and select AP transport Mode LAYER2, the Wizard does not ask the details of AP Manager.

  13. Enter the Virtual Gateway IP Address.

    This address can be any fictitious, unassigned IP address, such as 1.1.1.1, for the Layer 3 Security and Mobility managers to use.

    Note: Usually the Virtual Gateway IP Address that is used is a private address.

  14. Enter the Cisco WLAN Solution Mobility Group/RF Group name.

  15. Enter the WLAN 1 service set identifier (SSID) or network name.

    This identifier is the default SSID that lightweight APs use in order to associate to a WLC.

  16. Allow or disallow Static IP Addresses for clients.

    Enter yes in order to allow clients to supply their own IP addresses. Enter no in order to require clients to request an IP address from a DHCP server.

  17. If you need to configure a RADIUS server on the WLC, enter yes and enter this information:

    • RADIUS server IP address

    • The communication port

    • The shared secret

    If you do not need to configure a RADIUS server or you want to configure the server later, enter no.

  18. Enter a country code for the unit.

    Enter help in order to see a list of the supported countries.

  19. Enable and disable support for IEEE 802.11b, IEEE 802.11a, and IEEE 802.11g.

  20. Enable or disable radio resource management (RRM) (auto RF).

WLC 4402—Configuration Wizard

 
Welcome to the Cisco Wizard Configuration Tool
Use the '-' character to backup
System Name [Cisco_43:eb:22]: c4402
Enter Administrative User Name (24 characters max): admin
Enter Administrative Password (24 characters max): *****
Service Interface IP Address Configuration [none][DHCP]: none
Enable Link Aggregation (LAG) [yes][NO]: No
Management Interface IP Address: 192.168.60.2
Management Interface Netmask: 255.255.255.0
Management Interface Default Router: 192.168.60.1
Management Interface VLAN Identifier (0 = untagged): 60
Management Interface Port Num [1 to 2]: 1
Management Interface DHCP Server IP Address: 192.168.60.25
AP Transport Mode [layer2][LAYER3]: LAYER3
AP Manager Interface IP Address: 192.168.60.3
AP-Manager is on Management subnet, using same values
AP Manager Interface DHCP Server (192.168.50.3): 192.168.60.25
Virtual Gateway IP Address: 1.1.1.1
Mobility/RF Group Name: RFgroupname
Network Name (SSID): SSID
Allow Static IP Addresses [YES][no]: yes
Configure a RADIUS Server now? [YES][no]: no
Enter Country Code (enter 'help' for a list of countries) [US]: US
Enable 802.11b Network [YES][no]: yes
Enable 802.11a Network [YES][no]: yes
Enable 802.11g Network [YES][no]: yes
Enable Auto-RF [YES][no]: yes

Note: The management interface on the WLC is the only consistently pingable interface from outside of the WLC. So it is an expected behavior if you are not able to ping the AP manager interface from outside of the WLC.

Note: You must configure the AP manager interface in order for the APs to associate with the WLC.

Configure the Switch for the WLC

This example uses a Catalyst 3750 switch that uses only one port. The example tags the AP-manager and management interfaces and places these interfaces on VLAN 60. The switch port is configured as an IEEE 802.1Q trunk and only the appropriate VLANs, which are VLANs 2 through 4 and 60 in this case, are allowed on the trunk. The management and AP-manager VLAN (VLAN 60) is tagged and is not configured as the native VLAN of the trunk. So when the example configures those interfaces on the WLC, the interfaces are assigned a VLAN identifier.

This is an example 802.1Q switch port configuration:

interface GigabitEthernet1/0/1
description Trunk Port to Cisco WLC
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 2-4,60
switchport mode trunk
no shutdown

Note: When you connect the WLC gigabit port, make sure it is connected to the switch gigabit port only. If you connect the WLC gigabit Ethernet to the Switch FastEthernet port then it will not work.

Notice that this configuration example configures the neighbor switch port in a way that only allows relevant VLANs on the 802.1Q trunk. All other VLANs are pruned. This type of configuration is not necessary, but it is a deployment best practice. When you prune irrelevant VLANs, the WLC only processes relevant frames, which optimizes performance.

Configure the Switch for the APs

This is an example VLAN interface configuration from the Catalyst 3750:

interface VLAN5
description AP VLAN
ip address 10.5.5.1 255.255.255.0

While the Cisco WLCs always connect to 802.1Q trunks, Cisco lightweight APs do not understand VLAN tagging and should only be connected to the access ports of the neighbor switch.

This is an example switch port configuration from the Catalyst 3750:

interface GigabitEthernet1/0/22
description Access Port Connection to Cisco Lightweight AP
switchport access vlan 5
switchport mode access
no shutdown

The infrastructure is now ready for connection to the APs.

Verify

Use this section in order to confirm that your configuration works properly.

After the APs register with the controller, you can view them under Wireless at the top of the user interface of the controller:

wlc_lwap_config-2.gif

On the CLI, you can use the show ap summary command in order to verify that the APs registered with the WLC:

((Cisco Controller) >show ap summary

AP Name        Slots  AP Model   Ethernet MAC       Location          Port
-------------  -----  ---------  -----------------  ----------------  ----
ap:64:a3:a0    2      AP1010     00:0b:85:64:a3:a0  default_location  1

(Cisco Controller) >

On the WLC CLI, you can also use the show client summary command in order to see the clients that are registered with the WLC:

(Cisco Controller) >show client summary

Number of Clients................................ 1

MAC Address        AP Name        Status         WLAN  Auth  Protocol  Port
-----------------  -------------  -------------  ----  ----  --------  ----
00:40:96:a1:45:42  ap:64:a3:a0    Associated     4     Yes   802.11a   1

(Cisco Controller) >

Troubleshoot

Use this section in order to troubleshoot your configuration.

Commands

Use these commands in order to troubleshoot your configuration.

Note: Refer to Important Information on Debug Commands before you use debug commands.

This debug lwapp events enable WLC command output shows that the lightweight AP gets registered to the WLC:

(Cisco Controller) >debug lwapp events enable
Tue Apr 11 13:38:47 2006: Received LWAPP DISCOVERY REQUEST from AP 
    00:0b:85:64:a3:a0 to ff:ff:ff:ff:ff:ff on port '1'
Tue Apr 11 13:38:47 2006: Successful transmission of LWAPP Discovery-Response 
    to AP 00:0b:85:64:a3:a0 on Port 1
Tue Apr 11 13:38:58 2006: Received LWAPP JOIN REQUEST from AP 
    00:0b:85:64:a3:a0 to 00:0b:85:33:a8:a0 on port '1'
Tue Apr 11 13:38:58 2006: LWAPP Join-Request MTU path from AP 00:0b:85:64:a3:a0
    is 1500, remote debug mode is 0
Tue Apr 11 13:38:58 2006: Successfully added NPU Entry for AP 
    00:0b:85:64:a3:a0 (index 48) Switch IP: 192.168.60.2, Switch Port: 12223, 
    intIfNum 1, vlanId 60 AP IP: 10.5.5.10, AP Port: 19002, next hop MAC: 
    00:0b:85:64:a3:a0
Tue Apr 11 13:38:58 2006: Successfully transmission of LWAPP Join-Reply to AP 
    00:0b:85:64:a3:a0
Tue Apr 11 13:38:58 2006: Register LWAPP event for AP 
    00:0b:85:64:a3:a0 slot 0
Tue Apr 11 13:38:58 2006: Register LWAPP event for AP 00:0b:85:64:a3:a0 slot 1
Tue Apr 11 13:39:00 2006: Received LWAPP CONFIGURE REQUEST from AP 
    00:0b:85:64:a3:a0 to 00:0b:85:33:a8:a0
Tue Apr 11 13:39:00 2006: Updating IP info for AP 00:0b:85:64:a3:a0 -- 
    static 0, 10.5.5.10/255.255.255.0, gtw 192.168.60.1
Tue Apr 11 13:39:00 2006: Updating IP 10.5.5.10 ===> 10.5.5.10 for AP 
    00:0b:85:64:a3:a0
Tue Apr 11 13:39:00 2006: spamVerifyRegDomain RegDomain set for slot 0 code 0 
    regstring -A regDfromCb -A
Tue Apr 11 13:39:00 2006: spamVerifyRegDomain RegDomain set for slot 1 code 0 
    regstring -A regDfromCb -A
Tue Apr 11 13:39:00 2006: spamEncodeDomainSecretPayload:Send domain secret 
    Mobility Group<6f,39,74,cd,7e,a4,81,86,ca,32,8c,06,d3,ff,ec,6d,95,10,99,dd> 
    to AP 00:0b:85:64:a3:a0
Tue Apr 11 13:39:00 2006: Successfully transmission of LWAPP 
    Config-Message to AP 00:0b:85:64:a3:a0
Tue Apr 11 13:39:00 2006: Running spamEncodeCreateVapPayload for SSID 'SSID'
Tue Apr 11 13:39:00 2006: AP 00:0b:85:64:a3:a0 associated. Last AP failure was 
    due to Configuration changes, reason:  operator changed 11g mode
Tue Apr 11 13:39:00 2006: Received LWAPP CHANGE_STATE_EVENT from AP 
    00:0b:85:64:a3:a0
Tue Apr 11 13:39:00 2006: Successfully transmission of LWAPP Change-State-Event 
    Response to AP 00:0b:85:64:a3:a0
Tue Apr 11 13:39:00 2006: Received LWAPP Up event for AP 00:0b:85:64:a3:a0 slot 0!
Tue Apr 11 13:39:00 2006: Received LWAPP CONFIGURE COMMAND RES from AP 
    00:0b:85:64:a3:a0
Tue Apr 11 13:39:00 2006: Received LWAPP CHANGE_STATE_EVENT from AP 
    00:0b:85:64:a3:a0
Tue Apr 11 13:39:00 2006: Successfully transmission of LWAPP Change-State-Event 
    Response to AP 00:0b:85:64:a3:a0
Tue Apr 11 13:39:00 2006: Received LWAPP Up event for AP 
    00:0b:85:64:a3:a0 slot 1!

This output shows these useful WLC debug commands:

Tue Apr 11 14:30:49 2006: Applied policy for mobile 00:40:96:a1:45:42
Tue Apr 11 14:30:49 2006: STA [00:40:96:a1:45:42, 192.168.1.41] Replacing Fast 
    Path rule type = Airespace AP Client  on AP 00:0B:85:64:A3:A0, slot 0  
    InHandle = 0x00000000, OutHandle = 0x00000000  ACL Id = 255, Jumbo Frames 
				= NO, interface = 1  802.1P = 0, DSCP = 0, T
Tue Apr 11 14:30:49 2006: Successfully plumbed mobile rule for mobile 
    00:40:96:a1:45:42 (ACL ID 255)
Tue Apr 11 14:30:49 2006: Plumbed mobile LWAPP rule on AP 00:0b:85:64:a3:a0 
    for mobile 00:40:96:a1:45:42
Tue Apr 11 14:30:53 2006: DHCP proxy received packet, src: 0.0.0.0, 
    len = 320
Tue Apr 11 14:30:53 2006: dhcpProxy: Received packet: Client 00:40:96:a1:45:42 
    DHCP Op: BOOTREQUEST(1), IP len: 320, switchport: 1, encap: 0xec03
Tue Apr 11 14:30:53 2006: dhcpProxy(): dhcp request, client: 
    00:40:96:a1:45:42: dhcp op: 1, port: 1, encap 0xec03, old mscb 
    port number: 1
Tue Apr 11 14:30:53 2006: dhcp option len, including the magic cookie = 84
Tue Apr 11 14:30:53 2006: dhcp option: received DHCP REQUEST msg
Tue Apr 11 14:30:53 2006: dhcp option: skipping option 61, len 7
Tue Apr 11 14:30:53 2006: dhcp option: requested ip = 192.168.1.41
Tue Apr 11 14:30:53 2006: dhcp option: skipping option 12, len 15
Tue Apr 11 14:30:53 2006: dhcp option: skipping option 81, len 19
Tue Apr 11 14:30:53 2006: dhcp option: vendor class id = MSFT 5.0 (len 8)
Tue Apr 11 14:30:53 2006: dhcp option: skipping option 55, len 11
Tue Apr 11 14:30:53 2006: dhcpParseOptions: options end, len 84, actual 84
Tue Apr 11 14:30:53 2006: mscb->dhcpServer: 192.168.60.2, mscb->dhcpNetmask: 
    255.255.255.0,mscb->dhcpGateway: 192.168.60.1, mscb->dhcpRelay:
    192.168.60.2 VLAN: 60
Tue Apr 11 14:30:53 2006: Local Address: 192.168.60.2, DHCP Server: 
    192.168.60.2, Gateway Addr: 192.168.60.2, VLAN: 60, port: 1
Tue Apr 11 14:30:53 2006: DHCP Message Type received: DHCP REQUEST msg
Tue Apr 11 14:30:53 2006:   op: BOOTREQUEST, htype: Ethernet, hlen: 6, hops: 1
Tue Apr 11 14:30:53 2006:   xid: 3371152053, secs: 0, flags: 0
Tue Apr 11 14:30:53 2006:   chaddr: 00:40:96:a1:45:42
Tue Apr 11 14:30:53 2006:   ciaddr: 0.0.0.0,  yiaddr: 0.0.0.0
Tue Apr 11 14:30:53 2006:   siaddr: 0.0.0.0,  giaddr: 192.168.60.2
Tue Apr 11 14:30:53 2006: Forwarding DHCP packet locally (348 octets) from 
    192.168.60.2 to 192.168.60.2
Tue Apr 11 14:30:53 2006: Received 348 byte dhcp packet from 0x0201a8c0 
    192.168.60.2:68
Tue Apr 11 14:30:53 2006: DHCP packet: 192.168.60.2 -> 192.168.60.2 using 
    scope "InternalScope"
Tue Apr 11 14:30:53 2006: received REQUEST
Tue Apr 11 14:30:53 2006: Checking node 192.168.1.41  Allocated 1144765719, 
    Expires 1144852119 (now: 1144765853) 
Tue Apr 11 14:30:53 2006: adding option 0x35
Tue Apr 11 14:30:53 2006: adding option 0x36
Tue Apr 11 14:30:53 2006: adding option 0x33
Tue Apr 11 14:30:53 2006: adding option 0x03
Tue Apr 11 14:30:53 2006: adding option 0x01
Tue Apr 11 14:30:53 2006: dhcpd: Sending DHCP packet (giaddr:192.168.60.2)to 
192.168.60.2:67  from 192.168.60.2:1067
Tue Apr 11 14:30:53 2006: sendto (548 bytes) returned 548
Tue Apr 11 14:30:53 2006: DHCP proxy received packet, src: 192.168.60.2, 
    len = 548
Tue Apr 11 14:30:53 2006: dhcpProxy: Received packet: Client 00:40:96:a1:45:42
    DHCP Op: BOOTREPLY(2), IP len: 548, switchport: 0, encap: 0x0
Tue Apr 11 14:30:53 2006: dhcp option len, including the magic cookie = 312
Tue Apr 11 14:30:53 2006: dhcp option: received DHCP ACK msg
Tue Apr 11 14:30:53 2006: dhcp option: server id = 192.168.60.2
Tue Apr 11 14:30:53 2006: dhcp option: lease time (seconds) = 86400
Tue Apr 11 14:30:53 2006: dhcp option: gateway = 192.168.60.1
Tue Apr 11 14:30:53 2006: dhcp option: netmask = 255.255.255.0
Tue Apr 11 14:30:53 2006: dhcpParseOptions: options end, len 312, actual 64
Tue Apr 11 14:30:53 2006: DHCP Reply to AP client: 00:40:96:a1:45:42, 
    frame len 412, switchport 1
Tue Apr 11 14:30:53 2006: DHCP Message Type received: DHCP ACK msg
Tue Apr 11 14:30:53 2006:   op: BOOTREPLY, htype: Ethernet, hlen: 6, hops: 0
Tue Apr 11 14:30:53 2006:   xid: 3371152053, secs: 0, flags: 0
Tue Apr 11 14:30:53 2006:   chaddr: 00:40:96:a1:45:42
Tue Apr 11 14:30:53 2006:   ciaddr: 0.0.0.0,  yiaddr: 192.168.1.41
Tue Apr 11 14:30:53 2006:   siaddr: 0.0.0.0,  giaddr: 0.0.0.0
Tue Apr 11 14:30:53 2006:   server id: 1.1.1.1  rcvd server id: 192.168.60.2

You can use these additional debug commands in order to troubleshoot your configuration:

  • debug lwapp errors enable—Shows output of the debug of LWAPP errors

  • debug pm pki enable—Shows the debug of certificate messages that are passed between the AP and the WLC

Controller Does Not Defend AP-Manager IP Address

This issues is a result of bug CSCsg75863. If the user accidently injects a device on the subnet that uses the AP-manager IP address of the controller, the Address Resolution Protocol (ARP) cache on the default gateway router is refreshed with the wrong MAC address. When this occurs, the APs can no longer reach the controller and drop into their discovery phase to look for a controller. The APs send discovery requests, and the controller responds with discovery replies, but the JOIN requests never reach the AP-manager interface of the controller because of the bad ARP entry on the gateway router. After the default 4 hour ARP refresh interval, the APs join the controller if the device is removed.

A workaround for this issue is to configure the static ARP entries on the gateway router of the controller for these IP addresses:

  • Management IP address—Customers gain access to the graphical user interface (GUI) from another subnet, and the controller receives the AP discovery requests.

  • AP-Manager IP address—APs join the controller from another subnet.

  • Every Dynamic interface IP address—Packets from other subnets reach the dynamic interface of the controller.

DHCP packets transmit from the interface of the wireless client. Telnet or SSH to the gateway address of the controller, and use the arp <ip address> <hhhh.hhhh.hhhh> command in order to add the ARP entries. Use the ping command on the default router of the controller to the different addresses in order to refresh the ARP cache on the router. In order to discover the MAC addresses, use this command: show arp | include <ip address>.

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Related Information

Updated: Jan 21, 2008Document ID: 69719