Cisco IOS Software Configuration Guide for Cisco Aironet Access Points, 12.4(3g)JA & 12.3(8)JEB
Chapter 19 - Configuring Repeater and Standby Access Points and Workgroup Bridge Mode
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Configuring Repeater and Standby Access Points and Workgroup Bridge Mode

Table Of Contents

Configuring Repeater and Standby Access Points and Workgroup Bridge Mode

Understanding Repeater Access Points

Configuring a Repeater Access Point

Default Configuration

Guidelines for Repeaters

Setting Up a Repeater

Aligning Antennas

Verifying Repeater Operation

Setting Up a Repeater As a LEAP Client

Setting Up a Repeater As a WPA Client

Understanding Hot Standby

Configuring a Hot Standby Access Point

Verifying Standby Operation

Understanding Workgroup Bridge Mode

Treating Workgroup Bridges as Infrastructure Devices or as Client Devices

Configuring a Workgroup Bridge for Roaming

Configuring a Workgroup Bridge for Limited Channel Scanning

Configuring the Limited Channel Set

Ignoring the CCX Neighbor List

Configuring a Client VLAN

Configuring Workgroup Bridge Mode

The Workgroup Bridge in a Lightweight Environment

Guidelines for Using Workgroup Bridges in a Lightweight Environment

Sample Workgroup Bridge Configuration


Configuring Repeater and Standby Access Points and Workgroup Bridge Mode


This chapter describes how to configure your access point as a repeater, as a hot standby unit, or as a workgroup bridge. This chapter contains these sections:

Understanding Repeater Access Points

Configuring a Repeater Access Point

Understanding Hot Standby

Configuring a Hot Standby Access Point

Understanding Workgroup Bridge Mode

Configuring Workgroup Bridge Mode

The Workgroup Bridge in a Lightweight Environment

Understanding Repeater Access Points

A repeater access point is not connected to the wired LAN; it is placed within radio range of an access point connected to the wired LAN to extend the range of your infrastructure or to overcome an obstacle that blocks radio communication. You can configure either the 2.4-GHz radio or the 5-GHz radio as a repeater. In access points with two radios, only one radio can be a repeater; the other radio must be configured as a root radio.

The repeater forwards traffic between wireless users and the wired LAN by sending packets to either another repeater or to an access point connected to the wired LAN. The data is sent through the route that provides the best performance for the client. When you configure an access point as a repeater, the access point's Ethernet port does not forward traffic.

You can set up a chain of several repeater access points, but throughput for client devices at the end of the repeater chain will be quite low. Because each repeater must receive and then re-transmit each packet on the same channel, throughput is cut in half for each repeater you add to the chain.

A repeater access point associates to the access point with which it has the best connectivity. However, you can specify the access point to which the repeater associates. Setting up a static, specific association between a repeater and a root access point improves repeater performance.

To set up repeaters, you must enable Aironet extensions on both the parent (root) access point and the repeater access points. Aironet extensions, which are enabled by default, improve the access point's ability to understand the capabilities of Cisco Aironet client devices associated with the access point. Disabling Aironet extensions sometimes improves the interoperability between the access point and non-Cisco client devices. Non-Cisco client devices might have difficulty communicating with repeater access points and the root access point to which repeaters are associated.

The infrastructure SSID must be assigned to the native VLAN. If more than one VLAN is created on an access point or wireless bridge, an infrastructure SSID cannot be assigned to a non-native VLAN. The following message appears when the infrastructure SSID is configured on non-native VLAN:

SSID [xxx] must be configured as native-vlan before enabling infrastructure-ssid

Note Because access points create a virtual interface for each radio interface, repeater access points associate to the root access point twice: once for the actual interface and once for the virtual interface.



Note You cannot configure multiple VLANs on repeater access points. Repeater access points support only the native VLAN.


Figure 19-1 shows an access point acting as a repeater.

Figure 19-1 Access Point as a Repeater

Configuring a Repeater Access Point

This section provides instructions for setting up an access point as a repeater and includes these sections:

Default Configuration

Guidelines for Repeaters

Setting Up a Repeater

Verifying Repeater Operation

Aligning Antennas

Setting Up a Repeater As a LEAP Client

Setting Up a Repeater As a WPA Client

Default Configuration

Access points are configured as root units by default. Table 19-1 shows the default values for settings that control the access point's role in the wireless LAN.

Table 19-1 Default Settings for Role in Wireless LAN

Feature
Default Setting

Station role

Root

Parent

none

Extensions

Aironet


Guidelines for Repeaters

Follow these guidelines when configuring repeater access points:

Use repeaters to serve client devices that do not require high throughput. Repeaters extend the coverage area of your wireless LAN, but they drastically reduce throughput.

Use repeaters when most if not all client devices that associate with the repeaters are Cisco Aironet clients. Non-Cisco client devices sometimes have trouble communicating with repeater access points.

Make sure that the data rates configured on the repeater access point match the data rates on the parent access point. For instructions on configuring data rates, see the "Configuring Radio Data Rates" section.

Repeater access points support only the native VLAN. You cannot configure multiple VLANs on a repeater access point.


Note Repeater access points running Cisco IOS software cannot associate to parent access points that that do not run Cisco IOS software.



Note Repeater access points do not support wireless domain services (WDS). Do not configure a repeater access point as a WDS candidate, and do not configure a WDS access point to fall back to repeater mode in case of Ethernet failure.



Note If multiple BSSIDs are configured on a root access point that is designated as the parent of a repeater, the parent MAC address might change if a BSSID on the parent is added or deleted. If you use multiple BSSIDs on your wireless LAN and a repeater on your wireless LAN is configured to associate to a specific parent, check the association status of the repeater when you add or delete BSSIDs on the parent access point. If necessary, reconfigure the disassociated device to use the BSSID's new MAC address.


Setting Up a Repeater

Beginning in Privileged Exec mode, follow these steps to configure an access point as a repeater:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface dot11radio { 0 | 1 }

Enter interface configuration mode for the radio interface. The 2.4-GHz radio is radio 0, and the 5-GHz radio is radio 1.

Step 3 

ssid ssid-string

Create the SSID that the repeater uses to associate to a root access point; in the next step designate this SSID as an infrastructure SSID. If you created an infrastructure SSID on the root access point, create the same SSID on the repeater, also.

Step 4 

infrastructure-ssid [optional]

Designate the SSID as an infrastructure SSID. The repeater uses this SSID to associate to the root access point. Infrastructure devices must associate to the repeater access point using this SSID unless you also enter the optional keyword.

The infrastructure SSID must be assigned to the native VLAN. If more than one VLAN is created on an access point or wireless bridge, an infrastructure SSID cannot be assigned to a non-native VLAN. The following message appears when the infrastructure SSID is configured on non-native VLAN:

SSID [xxx] must be configured as native-vlan before enabling infrastructure-ssid

Step 5 

exit

Exit SSID configuration mode and return to radio interface configuration mode.

Step 6 

station-role repeater

Set the access point's role in the wireless LAN to repeater.

Step 7 

dot11 extensions aironet

If Aironet extensions are disabled, enable Aironet extensions.

Step 8 

parent {1-4} mac-address [timeout]

(Optional) Enter the MAC address for the access point to which the repeater should associate.

You can enter MAC addresses for up to four parent access points. The repeater attempts to associate to MAC address 1 first; if that access point does not respond, the repeater tries the next access point in its parent list.

Note If multiple BSSIDs are configured on the parent access point, the MAC address for the parent might change if a BSSID on the parent is added or deleted.

(Optional) You can also enter a timeout value in seconds that determines how long the repeater attempts to associate to a parent access point before trying the next parent in the list. Enter a timeout value from 0 to 65535 seconds.

Step 9 

end

Return to privileged EXEC mode.

Step 10 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

This example shows how to set up a repeater access point with three potential parents:

AP# configure terminal
AP(config)# interface dot11radio 0
AP(config-if)# ssid chicago
AP(config-ssid)# infrastructure-ssid
AP(config-ssid)# exit
AP(config-if)# station-role repeater
AP(config-if)# dot11 extensions aironet
AP(config-if)# parent 1 0987.1234.h345 900
AP(config-if)# parent 2 7809.b123.c345 900
AP(config-if)# parent 3 6543.a456.7421 900
AP(config-if)# end
 
   

Aligning Antennas

When an access point is configured as a repeater, you can align its antenna with another remote antenna using the dot11 antenna-alignment CLI command.

The command invokes an alignment test. The radio disassociates from its parent, probes adjacent wireless devices, and records the MAC addresses and signal strengths of responses it receives. After the timeout, the radio reassociates with its parent.

Follow these steps to run an antenna alignment test:

 
Command
Purpose

Step 1 

enable

Enter privileged EXEC mod

Step 2 

dot11 dot11radio { 0 | 1 }

Enter interface configuration mode for the radio interface. The 2.4-GHz radio is radio 0, and the 5-GHz radio is radio 1.

Step 3 

antenna-alignment timeout

Establish the time in seconds that the antenna alignment test runs before timing out. The default is 5 seconds.

Use the show dot11 antenna-alignment command to list the MAC addresses and signal level for the last 10 devices that responded to the probe.

Verifying Repeater Operation

After you set up the repeater, check the LEDs on top of the repeater access point. If your repeater is functioning correctly, the LEDs on the repeater and the root access point to which it is associated behave like this:

The status LED on the root access point is steady green, indicating that at least one client device is associated with it (in this case, the repeater).

The status LED on the repeater access point is steady green when it is associated with the root access point and the repeater has client devices associated to it. The repeater's status LED flashes (steady green for 7/8 of a second and off for 1/8 of a second) when it is associated with the root access point but the repeater has no client devices associated to it.

The repeater access point should also appear as associated with the root access point in the root access point's Association Table.

Setting Up a Repeater As a LEAP Client

You can set up a repeater access point to authenticate to your network like other wireless client devices. After you provide a network username and password for the repeater access point, it authenticates to your network using LEAP, Cisco's wireless authentication method, and receives and uses dynamic WEP keys.

Setting up a repeater as a LEAP client requires three major steps:

1. Create an authentication username and password for the repeater on your authentication server.

2. Configure LEAP authentication on the root access point to which the repeater associates. The access point to which the repeater associates is called the parent access point. See Chapter 11 "Configuring Authentication Types," for instructions on setting up authentication.


Note On the repeater access point, you must enable the same cipher suite or WEP encryption method and WEP features that are enabled on the parent access point.


3. Configure the repeater to act as a LEAP client. Beginning in Privileged Exec mode, follow these instructions to set up the repeater as a LEAP client:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface dot11radio { 0 | 1 }

Enter interface configuration mode for the radio interface. The 2.4-GHz radio is radio 0, and the 5-GHz radio is radio 1.

Step 3 

ssid ssid-string

Create an SSID and enter SSID configuration mode for the new SSID. The SSID can consist of up to 32 alphanumeric characters, but they should not include spaces. SSIDs are case-sensitive.

Step 4 

authentication network-eap list-name

Enable LEAP authentication on the repeater so that LEAP-enabled client devices can authenticate through the repeater. For list-name, specify the list name you want to use for EAP authentication. You define list names for EAP and for MAC addresses using the aaa authentication login command. These lists define the authentication methods activated when a user logs in and indirectly identify the location where the authentication information is stored.

Step 5 

authentication client username username
password password

Configure the username and password that the repeater uses when it performs LEAP authentication. This username and password must match the username and password that you set up for the repeater on the authentication server.

Step 6 

infrastructure ssid [optional]

(Optional) Designate the SSID as the SSID that other access points and workgroup bridges use to associate to this access point. If you do not designate an SSID as the infrastructure SSID, infrastructure devices can associate to the access point using any SSID. If you designate an SSID as the infrastructure SSID, infrastructure devices must associate to the access point using that SSID unless you also enter the optional keyword.

Step 7 

end

Return to privileged EXEC mode.

Step 8 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Setting Up a Repeater As a WPA Client

WPA key management uses a combination of encryption methods to protect communication between client devices and the access point. You can set up a repeater access point to authenticate to your network like other WPA-enabled client devices.

Beginning in Privileged Exec mode, follow these steps to set up the repeater as a WPA client:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface dot11radio { 0 | 1 }

Enter interface configuration mode for the radio interface. The 2.4-GHz radio is radio 0, and the 5-GHz radio is radio 1.

Step 3 

ssid ssid-string

Create an SSID and enter SSID configuration mode for the new SSID. The SSID can consist of up to 32 alphanumeric characters. SSIDs are case sensitive.

Step 4 

authentication open

Enable open authentication for the SSID.

Step 5 

authentication key-management wpa

Enable WPA authenticated key management for the SSID.

Step 6 

infrastructure ssid

Designate the SSID as the SSID that the repeater uses to associate to other access points.

Step 7 

wpa-psk { hex | ascii } [ 0 | 7 ] encryption-key

Enter a pre-shared key for the repeater.

Enter the key using either hexadecimal or ASCII characters. If you use hexadecimal, you must enter 64 hexadecimal characters to complete the 256-bit key. If you use ASCII, you must enter from 8 to 63 ASCII characters, and the access point expands the key for you.

Step 8 

end

Return to privileged EXEC mode.

Step 9 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Understanding Hot Standby

Hot Standby mode designates an access point as a backup for another access point. The standby access point is placed near the access point it monitors, configured exactly the same as the monitored access point. The standby access point associates with the monitored access point as a client and sends IAPP queries to the monitored access point through both the Ethernet and the radio ports. If the monitored access point fails to respond, the standby access point comes online and takes the monitored access point's place in the network.

Except for the IP address, the standby access point's settings should be identical to the settings on the monitored access point. If the monitored access point goes offline and the standby access point takes its place in the network, matching settings ensures that client devices can switch easily to the standby access point.

The standby access point monitors another access point in a device-to-device relationship, not in an interface-to-interface relationship. For example, you cannot configure the standby access point's 5-GHz radio to monitor the 5-GHz radio in access point alpha and the standby's 2.4-GHz radio to monitor the 2.4-GHz radio in access point bravo. You also cannot configure one radio in a dual-radio access point as a standby radio and configure the other radio to serve client devices.

Hot standby mode is disabled by default.


Note If the monitored access point malfunctions and the standby access point takes its place, repeat the hot standby setup on the standby access point when you repair or replace the monitored access point. The standby access point does not revert to standby mode automatically.



Note The MAC address of the monitored access point might change if a BSSID on the monitored unit is added or deleted. If you use multiple BSSIDs on your wireless LAN, check the status of the standby unit when you add or delete BSSIDs on the monitored access point. If necessary, reconfigure the standby unit to use the BSSID's new MAC address.


Configuring a Hot Standby Access Point

When you set up the standby access point, you must enter the MAC address of the access point that the standby unit will monitor. Record the MAC address of the monitored access point before you configure the standby access point.

The standby access point also must duplicate several key settings on the monitored access point. These settings are:

Primary SSID (as well as additional SSIDs configured on the monitored access point)

Default IP Subnet Mask

Default Gateway

Data rates

WEP settings

Authentication types and authentication servers

Check the monitored access point and record these settings before you set up the standby access point.


Note Wireless client devices associated to the standby access point lose their connections during the hot standby setup process.



Tip To quickly duplicate the monitored access point's settings on the standby access point, save the monitored access point configuration and load it on the standby access point. See the "Working with Configuration Files" section for instructions on uploading and downloading configuration files.


Beginning in Privileged Exec mode, follow these steps to enable hot standby mode on an access point:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

iapp standby mac-address

Puts the access point into standby mode and specifies the MAC address of radio on the monitored access point.

Note When you configure a 1200 Series access point with two radios to monitor a 1200 Series access point with two radios, you must enter the MAC addresses of both the monitored 2.4-GHz and 5-GHz radios. Enter the 2.4-GHz radio MAC address first, followed by the 5-GHz radio MAC address.

Note The MAC address of the monitored access point might change if a BSSID on the monitored unit is added or deleted. If you use multiple BSSIDs on your wireless LAN, check the status of the standby unit when you add or delete BSSIDs on the monitored access point. If necessary, reconfigure the standby unit to use the BSSID's new MAC address.

Step 3 

interface dot11radio { 0 | 1 }

Enter interface configuration mode for the radio interface. The 2.4-GHz radio is radio 0, and the 5-GHz radio is radio 1.

Step 4 

ssid ssid-string

Create the SSID that the standby access point uses to associate to the monitored access point; in the next step designate this SSID as an infrastructure SSID. If you created an infrastructure SSID on the monitored access point, create the same SSID on the standby access point, also.

Step 5 

infrastructure-ssid [optional]

Designate the SSID as an infrastructure SSID. The standby uses this SSID to associate to the monitored access point. If the standby access point takes the place of the monitored access point, infrastructure devices must associate to the standby access point using this SSID unless you also enter the optional keyword.

Step 6 

authentication client username username
password password

If the monitored access point is configured to require LEAP authentication, configure the username and password that the standby access point uses when it performs LEAP authentication. This username and password must match the username and password that you set up for the standby access point on the authentication server.

Step 7 

exit

Exit SSID configuration mode and return to radio interface configuration mode.

Step 8 

iapp standby poll-frequency seconds

Sets the number of seconds between queries that the standby access point sends to the monitored access point's radio and Ethernet ports. The default poll frequency is 2 seconds.

Step 9 

iapp standby timeout seconds

Sets the number of seconds the standby access point waits for a response from the monitored access point before it assumes that the monitored access point has malfunctioned. The default timeout is 20 seconds.

Note You should increase the standby timeout setting if the bridged path between the standby and monitored access points can be lost for periods greater than 20 seconds (during spanning tree recalculation, for example).

Note If the monitored access point is configured to select the least congested radio channel, you might need to increase the standby timeout setting. The monitored unit might take up to 40 seconds to select the least congested channel.

Step 10 

iapp standby primary-shutdown

(Optional) Configures the standby access point to send a Dumb Device Protocol (DDP) message to the monitored access point to disable the radios of the monitored access point when the standby unit becomes active. This feature prevents client devices that are associated to the monitored access point from remaining associated to the malfunctioning unit.

Step 11 

show iapp standby-parms

Verify your entries. If the access point is in standby mode, this command displays the standby parameters, including the MAC address of the monitored access point and the poll-frequency and timeout values. If the access point is not in standby mode, no iapp standby mac-address appears.

Step 12 

end

Return to privileged EXEC mode.

Step 13 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

After you enable standby mode, configure the settings that you recorded from the monitored access point to match on the standby access point.

Verifying Standby Operation

Use this command to check the status of the standby access point:

show iapp standby-status

This command displays the status of the standby access point. Table 19-2 lists the standby status messages that can appear.

Table 19-2 Standby Status Messages 

Message
Description

IAPP Standby is Disabled

The access point is not configured for standby mode.

IAPP—AP is in standby mode

The access point is in standby mode.

IAPP—AP is operating in active mode

The standby access point has taken over for the monitored access point and is functioning as a root access point.

IAPP—AP is operating in repeater mode

The standby access point has taken over for the monitored access point and is functioning as a repeater access point.

Standby status: Initializing

The standby access point is initializing link tests with the monitored access point.

Standby status: Takeover

The standby access point has transitioned to active mode.

Standby status: Stopped

Standby mode has been stopped by a configuration command.

Standby status: Ethernet Linktest Failed

An Ethernet link test failed from the standby access point to the monitored access point.

Standby status: Radio Linktest Failed

A radio link test failed from the standby access point to the monitored access point.

Standby status: Standby Error

An undefined error occurred.

Standby State: Init

The standby access point is initializing link tests with the monitored access point.

Standby State: Running

The standby access point is operating in standby mode and is running link tests to the monitored access point.

Standby State: Stopped

Standby mode has been stopped by a configuration command.

Standby State: Not Running

The access point is not in standby mode.


Use this command to check the standby configuration:

show iapp standby-parms

This command displays the MAC address of the standby access point, the standby timeout, and the poll-frequency values. If no standby access point is configured, this message appears:

no iapp standby mac-address
 
   

If a standby access point takes over for the monitored access point, you can use the show iapp statistics command to help determine the reason that the standby access point took over.

Understanding Workgroup Bridge Mode

You can configure 1100, 1130, 1200, 1230, and 1240 series access points as workgroup bridges. In workgroup bridge mode, the unit associates to another access point as a client and provides a network connection for the devices connected to its Ethernet port. For example, if you need to provide wireless connectivity for a group of network printers, you can connect the printers to a hub or to a switch, connect the hub or switch to the access point Ethernet port, and configure the access point as a workgroup bridge. The workgroup bridge associates to an access point on your network.

If your access point has two radios, either the 2.4-GHz radio or the 5-GHz radio can function in workgroup bridge mode. When you configure one radio interface as a workgroup bridge, the other radio interface the other remains up.


Caution An access point in workgroup bridge mode can introduce a bridge loop if you connect its Ethernet port to your wired LAN. To avoid a bridge loop on your network, disconnect the workgroup bridge from your wired LAN before or soon after you configure it as a workgroup bridge.


Note If multiple BSSIDs are configured on a root access point that is designated as the parent of a workgroup bridge, the parent MAC address might change if a BSSID on the parent is added or deleted. If you use multiple BSSIDs on your wireless LAN and a workgroup bridge on your wireless LAN is configured to associate to a specific parent, check the association status of the workgroup bridge when you add or delete BSSIDs on the parent access point. If necessary, reconfigure the workgroup bridge to use the BSSID's new MAC address.



Note Although it functions as a bridge, an access point in workgroup bridge mode has a limited radio range. Workgroup bridges do not support the distance setting, which enables you to configure wireless bridges to communicate across several kilometers.


Figure 19-2 shows an access point in workgroup bridge mode.

Figure 19-2 Access Point in Workgroup Bridge Mode

Treating Workgroup Bridges as Infrastructure Devices or as Client Devices

The access point to which a workgroup bridge associates can treat the workgroup bridge as an infrastructure device or as a simple client device. By default, access points and bridges treat workgroup bridges as client devices.

For increased reliability, you can configure access points and bridges to treat workgroup bridges not as client devices but as infrastructure devices, like access points or bridges. Treating a workgroup bridge as an infrastructure device means that the access point reliably delivers multicast packets, including Address Resolution Protocol (ARP) packets, to the workgroup bridge. You use the infrastructure-client configuration interface command to configure access points and bridges to treat workgroup bridges as infrastructure devices.

Configuring access points and bridges to treat a workgroup bridge as a client device allows more workgroup bridges to associate to the same access point, or to associate using an SSID that is not an infrastructure SSID. The performance cost of reliable multicast delivery—duplication of each multicast packet sent to each workgroup bridge—limits the number of infrastructure devices, including workgroup bridges, that can associate to an access point or bridge. To increase beyond 20 the number of workgroup bridges that can associate to the access point, the access point must reduce the delivery reliability of multicast packets to workgroup bridges. With reduced reliability, the access point cannot confirm whether multicast packets reach the intended workgroup bridge, so workgroup bridges at the edge of the access point's coverage area might lose IP connectivity. When you treat workgroup bridges as client devices, you increase performance but reduce reliability. You use the no infrastructure client configuration interface command to configure access points and bridges to treat workgroup bridges as simple client devices. This is the default setting.

You should use a workgroup bridge as an infrastructure device if the devices connected to the workgroup bridge require network reliability equivalent to that of an access point or a bridge. You should use a workgroup bridge as a client device if these conditions are true:

More than 20 workgroup bridges associate to the same access point or bridge

The workgroup bridge associates using an SSID that is not an infrastructure SSID

The workgroup bridge is mobile

Configuring a Workgroup Bridge for Roaming

If your workgroup bridge is mobile, you can configure it to scan for a better radio connection to a parent access point or bridge. Use this command to configure the workgroup bridge as a mobile station:

ap(config)# mobile station

When you enable this setting, the workgroup bridge scans for a new parent association when it encounters a poor Received Signal Strength Indicator (RSSI), excessive radio interference, or a high frame-loss percentage. Using these criteria, a workgroup bridge configured as a mobile station searches for a new parent association and roams to a new parent before it loses its current association. When the mobile station setting is disabled (the default setting) the workgroup bridge does not search for a new association until it loses its current association.

Configuring a Workgroup Bridge for Limited Channel Scanning

In mobile environments such as railroads, a workgroup bridge instead of scanning all the channels will be restricted to scan only a set of limited channels in order to reduce the hand-off delay when the workgroup bridge roams from one access point to another. By limiting the number of channels the workgroup bridge scans to only those required, the mobile workgroup bridge achieves and maintains a continuous wireless LAN connection with fast and smooth roaming.

Configuring the Limited Channel Set

This limited channel set is configured using the mobile station scan <set of channels> CLI command to invoke scanning to all or specified channels. There is no limitation on the maximum number of channels that can be configured. The maximum number of channels that can be configured is restricted only by the number of channels a radio can support. When executed, the workgroup bridge only scans this limited channel set. This limited channel feature also affects the known channel list that the workgroup bridge receives from the access point to which it is currently associated. Channels are added to the known channel list only if they are also a part of the limited channel set.

The following example shows how the command is used. In the example, channels 1, 6, and 11 are specified to scan:

ap#
ap#confure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
ap(config)#int d0
ap(config-if)#ssid limited_scan
ap(config-if)#station-role workgroup-bridge 
ap(config-if)#mobile station 
ap(config-if)#mobile station scan 1 6 11
ap(config-if)#end
ap#

Use the no mobile station scan command to restore scanning to all the channels.

Ignoring the CCX Neighbor List

In addition, the workgroup bridge updates its known channel list using CCX reports such as the AP Adjacent report or Enhanced Neighbor List report. However, when a workgroup bridge is configured for limited channel scanning, it does not need to process the CCX reports to update its known channel list. Use the mobile station ignore neighbor-list command to disable processing of CCX neighbor list reports. This command is effective only if the workgroup bridge is configured for limited scanning channel scanning. The following example shows how this command is used

ap#
ap#confure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
ap(config)#int d0
ap(config-if)#mobile station ignore neighbor-list 
ap(config-if)#end

Configuring a Client VLAN

If the devices connected to the workgroup bridge's Ethernet port should all be assigned to a particular VLAN, you can configure a VLAN for the connected devices. Enter this command on the workgroup bridge:

ap(config)# workgroup-bridge client-vlan vlan-id

All the devices connected to the workgroup bridge's Ethernet port are assigned to that VLAN.

Configuring Workgroup Bridge Mode

Beginning in privileged EXEC mode, follow these steps to configure an access point as a workgroup bridge:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface dot11radio {0 | 1}

Enter interface configuration mode for the radio interface.

Step 3 

station-role workgroup-bridge

Set the radio role to workgroup bridge. If your access point contains two radios, the radio not set to workgroup bridge mode is automatically disabled.

Step 4 

ssid ssid-string

Create the SSID that the workgroup bridge uses to associate to a parent access point or bridge.

Step 5 

infrastructure-ssid

Designate the SSID as an infrastructure SSID.

Note The workgroup bridge must use an infrastructure SSID to associate to a root access point or bridge.

Step 6 

authentication client
username
username
password password

(Optional) If the parent access point is configured to require LEAP authentication, configure the username and password that the workgroup bridge uses when it performs LEAP authentication. This username and password must match the username and password that you set up for the workgroup bridge on the authentication server.

Step 7 

exit

Exit SSID configuration mode and return to radio interface configuration mode.

Step 8 

parent {1-4} mac-address [timeout]

(Optional) Enter the MAC address for the access point to which the workgroup bridge should associate.

You can enter MAC addresses for up to four parent access points. The workgroup bridge attempts to associate to MAC address 1 first; if that access point does not respond, the workgroup bridge tries the next access point in its parent list.

Note If multiple BSSIDs are configured on the parent access point, the MAC address for the parent might change if a BSSID on the parent is added or deleted.

(Optional) You can also enter a timeout value in seconds that determines how long the workgroup bridge attempts to associate to a parent access point before trying the next parent in the list. Enter a timeout value from 0 to 65535 seconds.

Step 9 

exit

Exit radio configuration mode and return to global configuration mode.

Step 10 

workgroup-bridge client-vlan vlan-id

(Optional) Specify the VLAN to which the devices that are connected to the workgroup bridge's Ethernet port are assigned.

Step 11 

mobile station

(Optional) Configure the workgroup bridge as a mobile station. When you enable this setting, the workgroup bridge scans for a new parent association when it encounters a poor Received Signal Strength Indicator (RSSI), excessive radio interference, or a high frame-loss percentage. When this setting is disabled (the default setting) the workgroup bridge does not search for a new association until it loses its current association.

Step 12 

end

Return to privileged EXEC mode.

Step 13 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

This example shows how to configure an 1100 series access point as a workgroup bridge. In this example, the workgroup bridge uses the configured username and password to perform LEAP authentication, and the devices attached to its Ethernet port are assigned to VLAN 22:

AP# configure terminal
AP(config)# interface dot11radio 0
AP(config-if)# station-role workgroup-bridge
AP(config-if)# ssid infra
AP(config-ssid)# infrastructure-ssid
AP(config-ssid)# authentication client username wgb1 password cisco123
AP(config-ssid)# exit
AP(config-if)# exit
AP(config)# workgroup-bridge client-vlan 22
AP(config)# end
 
   

The Workgroup Bridge in a Lightweight Environment

You can configure an access point to operate as a workgroup bridge so that it can provide wireless connectivity to a lightweight access point on behalf of clients that are connected by Ethernet to the workgroup bridge access point. A workgroup bridge connects to a wired network over a single wireless segment by learning the MAC address of its wired clients on the Ethernet interface and reporting them to the lightweight access point using Internet Access Point Protocol (IAPP) messaging. The workgroup bridge provides wireless access connectivity to wired clients by establishing a single connection to the lightweight access point. The lightweight access point treats the workgroup bridge as a wireless clients. See the example in

Figure 19-3 Workgroup Bridge in a Lightweight Environment


Note If the lightweight access point fails, the workgroup bridge attempts to associate to another access point.


Guidelines for Using Workgroup Bridges in a Lightweight Environment

Follow these guidelines for using workgroup bridges on your lightweight network:

The workgroup bridge can be any autonomous access point that supports the workgroup bridge mode and is running Cisco IOS Release 12.4(3g)JA or greater (on 32-MB access points) or Cisco IOS Release 12.3(8)JEB or greater (on 16-MB access points). These access points include the AP1121, AP1130, AP1231, AP1240, and AP1310. Cisco IOS Releases prior to 12.4(eg)JA and 12.3(8)JEB are not supported.


Note If your access point has two radios, you can configure only one for workgroup bridge mode. This radio is used to connect to the lightweight access point. Cisco recommends that you disable the second radio.


Perform one of the following to enable the workgroup bridge mode on the workgroup bridge:

On the workgroup bridge access point GUI, choose Workgroup Bridge for the role in radio network on the Settings > Network Interfaces page.

On the workgroup bridge access point CLI, enter this command: station-role workgroup-bridge

The workgroup bridge can associate only to lightweight access points (except the Cisco Airespace AP1000 series access points, which are not supported).

Only workgroup bridge in client mode (which is the default value) are supported. Those in infrastructure mode are not supported. Perform one of the following to enable client mode on the workgroup bridge:

On the workgroup bridge access point GUI, choose Disabled for the Reliable Multicast to workgroup bridge parameter.

On the workgroup bridge access point CLI, enter this command: no infrastructure client.


Note VLANs are not supported for use with workgroup bridges.


These lightweight features are supported for use with a workgroup bridge:

Guest N+1 redundancy

Local EAP

These lightweight features are not supported for use with a workgroup bridge:

Cisco Centralized Key Management (CCKM)

Hybrid REAP

Idle timeout

Web authentication


Note If a workgroup bridge associates to a web-authentication WLAN, the workgroup bridge is added to the exclusion list, and all of the workgroup bridge wired clients are deleted.


In a mesh network, a workgroup bridge can associate to any mesh access point, regardless of whether it acts as a root access point or a mesh access point.

Wired clients connected to the workgroup bridge are not authenticated for security. Instead, the workgroup bridge is authenticated against the access point to which it associates. Therefore, Cisco recommends that you physically secure the wired side of the workgroup bridge.

With Layer 3 roaming, if you plug a wired client into the workgroup bridge network after the workgroup bridge has roamed to another controller (for example, to a foreign controller), the wired client's IP address displays only on the anchor controller, not on the foreign controller.

When you delete a workgroup bridge record from the controller, all of the workgroup bridge wired clients' records are also deleted.

Wired clients connected to a workgroup bridge inherit the workgroup bridge's QoS and AAA override attributes.

These features are not supported for wired clients connected to a workgroup bridge:

MAC filtering

Link tests

Idle timeout

You do not need to configure anything on the controller to enable the workgroup bridge to communicate with the lightweight access point. However, to ensure proper communication, you should create a WLAN on the controller that matches the SSID and security method that was configured on the workgroup bridge.

Sample Workgroup Bridge Configuration

Here is a sample configuration of a workgroup bridge access point using static WEP with a 40-bit WEP key:

ap#confure terminal
Enter configuration commands, one per line. End with CNTL/Z.
ap(config)#dot11 ssid WGB_with_static_WEP
ap(config-ssid)#authentication open
ap(config-ssid)#guest-mode
ap(config-ssid)#exit
ap(config)#interface dot11Radio 0
ap(config)#station-role workgroup-bridge
ap(config-if)#encry mode wep 40
ap(config-if)#encry key 1 size 40 0 1234567890
ap(config-if)#WGB_with_static_WEP
ap(config-if)#end
 
   

To verify that the workgroup bridge is associated to an access point, enter this command on the workgroup bridge:

show dot11 association

If a wired client does not send traffic for an extended period of time, the workgroup bridge removes the client from its bridge table, even if traffic is continuously being sent to the wired client. As a result, the traffic flow to the wired client fails. To avoid the traffic loss, prevent the wired client from being removed from the bridge table by configuring the aging-out timer on the workgroup bridge to a large value using the following IOS commands on the workgroup bridge:

configure terminal
bridge bridge-group-number aging-time seconds
exit
end
 
   

where bridge-group-number is a value between 1 and 255, and seconds is a value between 10 and 1,000,000 seconds. Cisco recommends configuring the seconds parameter to a value greater than the wired client's idle period.