Table Of Contents
Configuring Radio Settings
Enabling the Radio Interface
Configuring the Role in the Radio Network
Radio Tracking
Fast Ethernet Tracking
MAC-Address Tracking
Configuring Radio Data Rates
Configuring MCS Rates
Configuring Radio Transmit Power
Limiting the Power Level for Associated Client Devices
Configuring Radio Channel Settings
802.11n Channel Widths
Enabling and Disabling World Mode
Disabling and Enabling Short Radio Preambles
Configuring Transmit and Receive Antennas
Disabling and Enabling Aironet Extensions
Configuring the Ethernet Encapsulation Transformation Method
Enabling and Disabling Public Secure Packet Forwarding
Configuring Protected Ports
Configuring the Beacon Period and the DTIM
Configure RTS Threshold and Retries
Configuring the Maximum Data Retries
Configuring the Fragmentation Threshold
Enabling Short Slot Time for 802.11g Radios
Performing a Carrier Busy Test
Configuring VoIP Packet Handling
Configuring Radio Settings
This chapter describes how to configure radio settings for the wireless device in the following sections:
•
Enabling the Radio Interface
•Configuring the Role in the Radio Network
•Radio Tracking
•Configuring Radio Data Rates
•Configuring MCS Rates
•Configuring Radio Transmit Power
•Configuring Radio Channel Settings
•Enabling and Disabling World Mode
•Disabling and Enabling Short Radio Preambles
•Configuring Transmit and Receive Antennas
•Disabling and Enabling Aironet Extensions
•Configuring the Ethernet Encapsulation Transformation Method
•Enabling and Disabling Public Secure Packet Forwarding
•Configuring the Beacon Period and the DTIM
•Configure RTS Threshold and Retries
•Configuring the Maximum Data Retries
•Configuring the Fragmentation Threshold
•Enabling Short Slot Time for 802.11g Radios
•Performing a Carrier Busy Test
•Configuring VoIP Packet Handling
Enabling the Radio Interface
The wireless device radios are disabled by default.
Note You must create a service set identifier (SSID) before you can enable the radio interface.
To enable the access point radio, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
dot11 ssid ssid
|
Enters the SSID. The SSID consists of up to 32 alphanumeric characters. SSIDs are case sensitive.
|
Step 3
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface.The 2.4-GHz and 802.11g/n 2.4-GHz radios are radio 0.
|
Step 4
|
ssid ssid
|
Assigns the SSID that you created in Step 2 to the appropriate radio interface.
|
Step 5
|
no shutdown
|
Enables the radio port.
|
Step 6
|
end
|
Returns to privileged EXEC mode.
|
Step 7
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Use the shutdown command to disable the radio port.
Configuring the Role in the Radio Network
Table 10-1 shows the role that the radio performs in the wireless network.
Table 10-1 Device Role in Radio Network Configuration
Role in Radio Network
|
Cisco 860 ISR
|
Cisco 880 ISR
|
|
Access point
|
X
|
X
|
|
Access point (fallback to radio shutdown)
|
X
|
X
|
|
Root bridge
|
X
|
X
|
|
Non-root bridge
|
X
|
X
|
|
Root bridge with wireless clients
|
X
|
X
|
|
Non-root bridge with wireless clients
|
X
|
X
|
|
You can also configure a fallback role for root access points. The wireless device automatically assumes the fallback role when its Ethernet port is disabled or disconnected from the wired LAN. The default fallback role for Cisco ISR wireless devices is as follows:
Shutdown—the wireless device shuts down its radio and disassociates all client devices.
To set the wireless device's radio network role and fallback role, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface.
The 2.4-GHz and 802.11g/n 2.4-GHz radios are radio 0.
|
Step 3
|
station-role
non-root {bridge | wireless-clients}
root {access-point | ap-only | [bridge | wireless-clients] | [fallback | repeater | shutdown]}
workgroup-bridge {multicast | mode <client | infrastructure>| universal <Ethernet client MAC address>}
|
Sets the wireless device role.
•Set the role to non-root bridge with or without wireless clients, to root access point or bridge, or to workgroup bridge.
Note The bridge mode radio supports point-to-point configuration only.
Note The repeater and wireless-clients commands are not supported on Cisco 860 and Cisco 880 series embedded-wireless devices.
Note The scanner command is not supported on Cisco 860 and Cisco 880 series embedded-wireless devices.
•The Ethernet port is shut down when any one of the radios is configured as a repeater. Only one radio per access point may be configured as a workgroup bridge or repeater.
|
Step 4
|
end
|
Returns to privileged EXEC mode.
|
Step 5
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Note When you enable the role of a device in the radio network as a bridge/workgroup bridge and enable the interface using the no shut command, the physical status and the software status of the interface will be up (ready) only if the device on the other end (access point or bridge) is up. Otherwise, only the physical status of the device will be up. The software status will be up when the device on the other end is configured and ready.
Radio Tracking
You can configure the access point to track or monitor the status of one of its radios. If the tracked radio goes down or is disabled, the access point shuts down the other radio. If the tracked radio comes up, the access point enables the other radio.
•To track radio 0, enter the following command:
# station-role root access-point fallback track d0 shutdown
•To track radio 1, enter the following command:
# station-role root access-point fallback track d1 shutdown
Fast Ethernet Tracking
You can configure the access point for fallback when its Ethernet port is disabled or disconnected from the wired LAN. You configure the access point for Fast Ethernet tracking as described in the "Configuring the Role in the Radio Network" section.
Note Fast Ethernet tracking does not support the repeater mode.
•To configure the access point for Fast Ethernet tracking, enter the following command:
# station-role root access-point fallback track fa 0
MAC-Address Tracking
You can configure the radio whose role is root access point to come up or go down by tracking a client access point, using its MAC address, on another radio. If the client disassociates from the access point, the root access point radio goes down. If the client reassociates to the access point, the root access point radio comes back up.
MAC-address tracking is most useful when the client is a non-root bridge access point connected to an upstream wired network.
For example, to track a client whose MAC address is 12:12:12:12:12:12, enter the following command:
# station-role root access-point fallback track mac-address 12:12:12:12:12:12 shutdown
Configuring Radio Data Rates
You use the data rate settings to choose the data rates that the wireless device uses for data transmission. The rates are expressed in megabits per second (Mb/s). The wireless device always attempts to transmit at the highest data rate set to basic, also known as required on the browser-based interface. If there are obstacles or interference, the wireless device steps down to the highest rate that allows data transmission. You can set each data rate to one of three states:
•Basic (the GUI labels Basic rates as Required)—Allows transmission at this rate for all packets, both unicast and multicast. At least one of the wireless device's data rates must be set to basic.
•Enabled—The wireless device transmits only unicast packets at this rate; multicast packets are sent at one of the data rates set to basic.
•Disabled—The wireless device does not transmit data at this rate.
Note At least one data rate must be set to basic.
You can use the data rate settings to set an access point to serve client devices operating at specific data rates. For example, to set the 2.4-GHz radio for 11 Mb/s service only, set the 11-Mb/s rate to basic, and set the other data rates to disabled. To set the wireless device to serve only client devices operating at 1 and 2 Mb/s, set 1 and 2 to basic, and set the rest of the data rates to disabled. To set the 2.4-GHz, 802.11g radio to serve only 802.11g client devices, set any orthogonal frequency division multiplexing (OFDM) data rate (6, 9, 12, 18, 24, 36, 48, 54) to basic. To set the 5-GHz radio for 54-Mb/s service only, set the 54-Mb/s rate to basic, and set the other data rates to disabled.
You can configure the wireless device to set the data rates automatically to optimize either the range or the throughput. When you enter range for the data rate setting, the wireless device sets the 1-Mb/s rate to basic and stes the other rates to enabled. The range setting allows the access point to extend the coverage area by compromising on the data rate. Therefore, if you have a client that cannot connect to the access point while other clients can, the client might not be within the coverage area of the access point. In such a case, using the range option will help extend the coverage area, and the client may be able to connect to the access point. Typically the trade-off is between throughput and range. When the signal degrades (possibly due to distance from the access point), the rates renegotiate in order to maintain the link (but at a lower data rate). A link that is configured for a higher throughput simply drops when the signal degrades enough that it no longer sustains a configured high data rate, or the link roams to another access point with sufficient coverage, if one is available. The balance between the two (throughput vs. range) is a design decision that must be made based on resources available to the wireless project, the type of traffic the users will be passing, the service level desired, and as always, the quality of the RF environment.When you enter throughput for the data rate setting, the wireless device sets all four data rates to basic.
Note When a wireless network has a mixed environment of 802.11b clients and 802.11g clients, make sure that data rates 1, 2, 5.5, and 11 Mb/s are set to required (basic) and that all other data rates are set to enable. The 802.11b adapters do not recognize the 54 Mb/s data rate and do not operate if data rates higher than 11 Mb/s are set to required on the connecting access point.
To configure the radio data rates, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface. The 2.4-GHz and the 802.11g/n 2.4-GHz radios are radio 0.
|
Step 3
|
speed
802.11b, 2.4-GHz radio:
{[1.0] [11.0] [2.0] [5.5] [basic-1.0] [basic-11.0] [basic-2.0] [basic-5.5] | range | throughput}
802.11g, 2.4-GHz radio:
{[1.0] [2.0] [5.5] [6.0] [9.0] [11.0] [12.0] [18.0] [24.0] [36.0] [48.0] [54.0] [basic-1.0] [basic-2.0] [basic-5.5] [basic-6.0] [basic-9.0] [basic-11.0] [basic-12.0] [basic-18.0] [basic-24.0] [basic-36.0] [basic-48.0] [basic-54.0] | range |
throughput [ofdm] | default}
802.11a 5-GHz radio:
{[6.0] [9.0] [12.0] [18.0] [24.0] [36.0] [48.0] [54.0] [basic-6.0] [basic-9.0] [basic-12.0] [basic-18.0] [basic-24.0] [basic-36.0] [basic-48.0] [basic-54.0] |
range | throughput | ofdm-throughput | default}
802.11n 2.4-GHz radio on Cisco 860 and Cisco 880 ISR:
{[1.0] [11.0] [12.0] [18.0] [2.0] [24.0] [36.0] [48.0] [5.5] [54.0] [6.0] [9.0] [basic-1.0] [basic-11.0] [basic-12.0] [basic-18.0] [basic-24.0] [basic-36.0] [basic-48.0] [basic-5.5] [basic-54.0] [basic-6.0] [basic-9.0] [default] [m0-7] [m0.] [m1.] [m10.] [m11.] [m12.] [m13.] [m14.] [m15.] [m2.] [m3.] [m4.] [m5.] [m6.] [m7.] [m8-15] [m8.] [m9.] [ofdm] [only-ofdm] | range | throughput}
|
Sets each data rate to basic or enabled, or enters range to optimize range or enters throughput to optimize throughput.
•(Optional) Enter 1.0, 2.0, 5.5, and 11.0 to set these data rates to enabled on the 802.11b, 2.4-GHz radio.
Enter 1.0, 2.0, 5.5, 6.0, 9.0, 11.0, 12.0, 18.0, 24.0, 36.0, 48.0, and 54.0 to set these data rates to enabled on the 802.11g, 2.4-GHz radio.
Enter 6.0, 9.0, 12.0, 18.0, 24.0, 36.0, 48.0, and 54.0 to set these data rates to enabled on the 5-GHz radio.
•(Optional) Enter basic-1.0, basic-2.0, basic-5.5, and basic-11.0 to set these data rates to basic on the 802.11b, 2.4-GHz radio.
Enter basic-1.0, basic-2.0, basic-5.5, basic-6.0, basic-9.0, basic-11.0, basic-12.0, basic-18.0, basic-24.0, basic-36.0, basic-48.0, and basic-54.0 to set these data rates to basic on the 802.11g, 2.4-GHz radio.
Note If the client must support the basic rate that you select, it cannot associate to the wireless device. If you select 12-Mb/s or higher for the basic data rate on the 802.11g radio, 802.11b client devices cannot associate to the wireless device 802.11g radio.
Enter basic-6.0, basic-9.0, basic-12.0, basic-18.0, basic-24.0, basic-36.0, basic-48.0, and basic-54.0 to set these data rates to basic on the 5-GHz radio.
•(Optional) Enter range or throughput or ofdm-throughput (no ERP protection) to automatically optimize radio range or throughput. When you enter range, the wireless device sets the lowest data rate to basic and sets the other rates to enabled. When you enter throughput, the wireless device sets all data rates to basic.
(Optional) On the 802.11g radio, enter speed throughput ofdm to set all OFDM rates (6, 9, 12, 18, 24, 36, and 48) to basic (required) and to set all the CCK rates (1, 2, 5.5, and 11) to disabled. This setting disables 802.11b protection mechanisms and provides maximum throughput for 802.11g clients. However, it prevents 802.11b clients from associating to the access point.
•(Optional) Enter default to set the data rates to factory default settings (not supported on 802.11b radios).
On the 802.11g radio, the default option sets rates 1, 2, 5.5, and 11 to basic, and stes rates 6, 9, 12, 18, 24, 36, 48, and 54 to enabled. These rate settings allow both 802.11b and 802.11g client devices to associate to the wireless device 802.11g radio.
|
| |
speed (continued)
|
On the 5-GHz radio, the default option sets rates 6.0, 12.0, and 24.0 to basic, and stes rates 9.0, 18.0, 36.0, 48.0, and 54.0 to enabled.
On the 802.11g/n 2.4-GHz radio, the default option sets rates 1.0, 2.0, 5.5, and 11.0 to enabled.
On the 802.11g/n 5-GHz radio, the default option sets rates to 6.0, 12.0, and 24.0 to enabled.
The modulation coding scheme (MCS) index range for both 802.11g/n radios is 0 to 15.
|
Step 4
|
end
|
Returns to privileged EXEC mode.
|
Step 5
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Use the no form of the speed command to remove one or more data rates from the configuration. This example shows how to remove data rates basic-2.0 and basic-5.5 from the configuration:
ap1200# configure terminal
ap1200(config)# interface dot11radio 0
ap1200(config-if)# no speed basic-2.0 basic-5.5
Configuring MCS Rates
Modulation coding scheme (MCS) is a specification of PHY parameters consisting of modulation order (binary phase shift keying [BPSK], quaternary phase shift keying [QPSK], 16-quadrature amplitude modulation [16-QAM], 64-QAM) and forward error correction (FEC) code rate (1/2, 2/3, 3/4, 5/6). MCS is used in the wireless device 802.11n radios, which define 32 symmetrical settings (8 per spatial stream):
•MCS 0-7
•MCS 8-15
•MCS 16-23
•MCS 24-31
The wireless device supports MCS 0-15. High-throughput clients support at least MCS 0-7.
MCS is an important setting because it provides for potentially greater throughput. High-throughput data rates are a function of MCS, bandwidth, and guard interval. The 802.11a, b, and g radios use 20-MHz channel widths. Table 10-2 shows potential data rated based on MCS, guard interval, and channel width.
Table 10-2 Data Rates Based on MCS Settings, Guard Interval, and Channel Width
MCS Index
|
Guard Interval = 800 ns
|
Guard Interval = 400 ns
|
| |
20-MHz Channel Width Data Rate (Mb/s)
|
40-MHz Channel Width Data Rate (Mb/s)
|
20-MHz Channel Width Data Rate (Mb/s)
|
40-MHz Channel Width Data Rate (Mb/s)
|
0
|
6.5
|
13.5
|
7 2/9
|
15
|
1
|
13
|
27
|
14 4/9
|
30
|
2
|
19.5
|
40.5
|
21 2/3
|
45
|
3
|
26
|
54
|
28 8/9
|
60
|
4
|
39
|
81
|
43 1/3
|
90
|
5
|
52
|
109
|
57 5/9
|
120
|
6
|
58.5
|
121.5
|
65
|
135
|
7
|
65
|
135
|
72 2/9
|
152.5
|
8
|
13
|
27
|
14 4/9
|
30
|
9
|
26
|
54
|
28 8/9
|
60
|
10
|
39
|
81
|
43 1/3
|
90
|
11
|
52
|
108
|
57 7/9
|
120
|
12
|
78
|
162
|
86 2/3
|
180
|
13
|
104
|
216
|
115 5/9
|
240
|
14
|
117
|
243
|
130
|
270
|
15
|
130
|
270
|
144 4/9
|
300
|
The legacy rates are:as follows:
5 GHz: 6, 9, 12, 18, 24, 36, 48, and 54 Mb/s
2.4 GHz: 1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36, 48, and 54 Mb/s
|
MCS rates are configured using the speed command. The following example shows a speed setting for an 802.11g/n 2.4-GHz radio:
speed basic-1.0 2.0 5.5 11.0 6.0 9.0 12.0 18.0 24.0 36.0 48.0 54.0 m0. m1. m2. m3. m4.
m8. m9. m10. m11. m12. m13. m14. m15.
Configuring Radio Transmit Power
Radio transmit power is based on the type of radio or radios installed in your access point and the regulatory domain in which it operates.
To set the transmit power on access point radios, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface.
The 2.4-GHz and the 802.11g/n 2.4-GHz radios are radio 0.
|
Step 3
|
power local
These options are available for the 2.4-GHz 802.11n radio (in dBm):
{8 | 9| 11 | 14 | 15 | 17 | maximum}
|
Sets the transmit power for the radio so that the power level is allowed in your regulatory domain.
|
Step 4
|
end
|
Returns to privileged EXEC mode.
|
Step 5
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Use the no form of the power local command to return the power setting to maximum, the default setting.
Limiting the Power Level for Associated Client Devices
You can also limit the power level on client devices that associate to the wireless device. When a client device associates to the wireless device, the wireless device sends the maximum power level setting to the client.
Note Cisco AVVID documentation uses the term Dynamic Power Control (DPC) to refer to limiting the power level on associated client devices.
To specify a maximum allowed power setting on all client devices that associate to the wireless device, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface. The 2.4-GHz and 802.11g/n 2.4-GHz radios are radio 0.
|
Step 3
|
power client
These options are available for 802.11n 2.4-GHz clients (in dBm):
{local | 8 | 9 | 11 | 14 | 15 | 17 | maximum}
|
Sets the maximum power level allowed on client devices that associate to the wireless device.
Setting the power level to local sets the client power level to that of the access point.
Setting the power level to maximum sets the client power to the allowed maximum.
Note The settings allowed in your regulatory domain might differ from the settings listed here.
|
Step 4
|
end
|
Returns to privileged EXEC mode.
|
Step 5
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Use the no form of the power client command to disable the maximum power level for associated clients.
Note Aironet extensions must be enabled to limit the power level on associated client devices. Aironet extensions are enabled by default.
Configuring Radio Channel Settings
The default channel setting for the wireless device radios is least congested. At startup, the wireless device scans for and selects the least-congested channel. For the most consistent performance after a site survey, however, we recommend that you assign a static channel setting for each access point. The channel settings on the wireless device correspond to the frequencies available in your regulatory domain. See the access point's hardware installation guide for the frequencies allowed in your domain.
Each 2.4-GHz channel covers 22 MHz. Because the bands for channels 1, 6, and 11 do not overlap, you can set up multiple access points in the same vicinity without causing interference. The 802.11b and 802.11g 2.4-GHz radios use the same channels and frequencies.
The 5-GHz radio operates on 8 channels from 5180 to 5320 MHz, up to 27 channels from 5170 to 5850 MHz depending on regulatory domain. Each channel covers 20 MHz, and the bands for the channels overlap slightly. For best performance, use channels that are not adjacent (use channels 44 and 46, for example) for radios that are close to each other.
Note The presence of too many access points in the same vicinity can create radio congestion that can reduce throughput. A careful site survey can determine the best placement of access points for maximum radio coverage and throughput.
802.11n Channel Widths
The 802.11n standard allows both 20-MHz and 40-Mhz channel widths consisting of two contiguous non-overlapping channels (for example, 2.4-GHz channels 1 and 6)
One of the 20-MHz channels is called the control channel. Legacy clients and 20-MHz high-throughput clients use the control channel. Only beacons can be sent on this channel. The second 20-MHz channel is called the extension channel. The 40-MHz stations may use this channel and the control channel simultaneously.
A 40-MHz channel is specified as a channel and extension, such as 1,1. In this example, the control channel is channel 1 and the extension channel is above it.
To set the wireless device channel width, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0 }
|
Enters interface configuration mode for the radio interface. The 802.11g/n 2.4-GHz radio is radio 0.
|
Step 3
|
channel
{frequency | least-congested | width [20 | 40-above | 40-below] | dfs}
|
Sets the default channel for the wireless device radio.To search for the least-congested channel on startup, enter least-congested.
Use the width option to specify a bandwidth to use. This option is available for the Cisco 800 series ISR wireless devices and consists of three available settings: 20, 40-above, and 40-below:
•Choosing 20 sets the channel width to 20 MHz.
•Choosing 40-above sets the channel width to 40 MHz with the extension channel above the control channel.
•Choosing 40-below sets the channel width to 40 MHz with the extension channel below the control channel.
Note The channel command is disabled for 5-GHz radios that comply with European Union regulations on dynamic frequency selection (DFS). See the "Enabling and Disabling World Mode" section for more information.
|
Step 4
|
end
|
Returns to privileged EXEC mode.
|
Step 5
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Enabling and Disabling World Mode
You can configure the wireless device to support 802.11d world mode, Cisco legacy world mode, or world mode roaming. When you enable world mode, the wireless device adds channel carrier set information to its beacon. Client devices with world mode enabled receive the carrier set information and adjust their settings automatically. For example, a client device used primarily in Japan could rely on world mode to adjust its channel and power settings automatically when it travels to Italy and joins a network there. Cisco client devices detect whether the wireless device is using 802.11d or Cisco legacy world mode and automatically use the world mode that matches the mode used by the wireless device.
You can also configure world mode to be always on. In this configuration, the access point essentially roams between countries and changes its settings as required.
World mode is disabled by default.
To enable world mode, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface.
|
Step 3
|
world-mode
{dot11d country_code code
{both | indoor | outdoor}
| world-mode roaming | legacy}
|
Enables world mode.
•Enter the dot11d option to enable 802.11d world mode.
–When you enter the dot11d option, you must enter a 2-character ISO country code (for example, the ISO country code for the United States is US). You can find a list of ISO country codes at the ISO website.
–After the country code, you must enter indoor, outdoor, or both to indicate the placement of the wireless device.
•Enter the legacy option to enable Cisco legacy world mode.
•Enter the world-mode roaming option to place the access point in a continuous world mode configuration.
Note Aironet extensions must be enabled for legacy world mode operation, but Aironet extensions are not required for 802.11d world mode. Aironet extensions are enabled by default.
|
Step 4
|
end
|
Returns to privileged EXEC mode.
|
Step 5
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Use the no form of the world-mode command to disable world mode.
Disabling and Enabling Short Radio Preambles
The radio preamble (sometimes called a header) is a section of data at the head of a packet that contains information that the wireless device and client devices need when sending and receiving packets. You can set the radio preamble to long or short:
•Short—A short preamble improves throughput performance.
•Long—A long preamble ensures compatibility between the wireless device and all early models of Cisco Aironet Wireless LAN Adapters. If these client devices do not associate to the wireless devices, you should use short preambles.
You cannot configure short or long radio preambles on the 5-GHz radio.
To disable short radio preambles, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0 }
|
Enters interface configuration mode for the 2.4-GHz radio interface.
|
Step 3
|
no preamble-short
|
Disables short preambles and enable long preambles.
|
Step 4
|
end
|
Returns to privileged EXEC mode.
|
Step 5
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Short preambles are enabled by default. Use the preamble-short command to enable short preambles if they are disabled.
Configuring Transmit and Receive Antennas
You can select the antenna that the wireless device uses to receive and transmit data. There are three options for both the receive antenna and the transmit antenna:
•Gain—Sets the resultant antenna gain in decibels (dB).
•Diversity—This default setting tells the wireless device to use the antenna that receives the best signal. If the wireless device has two fixed (non-removable) antennas, you should use this setting for both receive and transmit.
•Right—If the wireless device has removable antennas and you install a high-gain antenna on the wireless device's right connector, you should use this setting for both receive and transmit. When you look at the wireless device's back panel, the right antenna is on the right.
•Left—If the wireless device has removable antennas and you install a high-gain antenna on the wireless device's left connector, you should use this setting for both receive and transmit. When you look at the wireless device's back panel, the left antenna is on the left.
To select the antennas that the wireless device uses to receive and transmit data, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface. The 802.11g/n 2.4-GHz radio is radio 0.
|
Step 3
|
gain dB
|
Specifies the resultant gain of the antenna attached to the device. Enter a value from -128 to 128 dB. If necessary, you can use a decimal in the value, such as 1.5.
Note The Cisco 860 and Cisco 880 ISRs are shipped with a fixed antenna that cannot be removed. Antenna gain cannot be configured.
|
Step 4
|
antenna receive
{diversity | left | right}
|
Sets the receive antenna to diversity, left, or right.
Note For best performance with two antennas, leave the receive antenna setting at the default setting, diversity. For one antenna, attach the antenna on the right and set the antenna for right.
|
Step 5
|
antenna transmit
{diversity | left | right}
|
Sets the transmit antenna to diversity, left, or right.
Note For best performance with two antennas, leave the receive antenna setting at the default setting, diversity. For one antenna, attach the antenna on the right and set the antenna for right.
|
Step 6
|
end
|
Returns to privileged EXEC mode.
|
Step 7
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Disabling and Enabling Aironet Extensions
By default, the wireless device uses Cisco Aironet 802.11 extensions to detect the capabilities of Cisco Aironet client devices and to support features that require specific interaction between the wireless device and associated client devices. Aironet extensions must be enabled to support these features:
•Load balancing—The wireless device uses Aironet extensions to direct client devices to an access point that provides the best connection to the network on the basis of such factors as number of users, bit error rates, and signal strength.
•Message Integrity Check (MIC)—MIC is an additional WEP security feature that prevents attacks on encrypted packets called bit-flip attacks. The MIC, implemented on the wireless device and all associated client devices, adds a few bytes to each packet to make the packets tamper-proof.
•Cisco Key Integrity Protocol (CKIP)—Cisco's WEP key permutation technique is based on an early algorithm presented by the IEEE 802.11i security task group. The standards-based algorithm, Temporal Key Integrity Protocol (TKIP), does not require Aironet extensions to be enabled.
•World mode (legacy only)—Client devices with legacy world mode enabled receive carrier set information from the wireless device and adjust their settings automatically. Aironet extensions are not required for 802.11d world mode operation.
•Limiting the power level on associated client devices—When a client device associates to the wireless device, the wireless device sends the maximum allowed power level setting to the client.
Disabling Aironet extensions disables the features listed above, but it sometimes improves the ability of non-Cisco client devices to associate to the wireless device.
Aironet extensions are enabled by default. To disable Aironet extensions, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface.
The 802.11g/n 2.4-GHz radio is radio 0.
|
Step 3
|
no dot11 extension aironet
|
Disables Aironet extensions.
|
Step 4
|
end
|
Returns to privileged EXEC mode.
|
Step 5
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Use the dot11 extension aironet command to enable Aironet extensions if they are disabled.
Configuring the Ethernet Encapsulation Transformation Method
When the wireless device receives data packets that are not 802.3 packets, the wireless device must format the packets to 802.3 by using an encapsulation transformation method. These are the two transformation methods:
•802.1H—This method provides optimum performance for Cisco wireless products.
•RFC 1042—Use this setting to ensure interoperability with non-Cisco wireless equipment. RFC1042 does not provide the interoperability advantages of 802.1H but is used by other manufacturers of wireless equipment.
To configure the encapsulation transformation method, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface. The 802.11g/n 2.4-GHz radio is radio 0.
|
Step 3
|
payload-encapsulation
{snap | dot1h}
|
Sets the encapsulation transformation method to RFC 1042 (snap) or 802.1h (dot1h, the default setting).
|
Step 4
|
end
|
Returns to privileged EXEC mode.
|
Step 5
|
copy running-config startup-config
|
(Optional) Saves your entries in the configuration file.
|
Enabling and Disabling Public Secure Packet Forwarding
Public Secure Packet Forwarding (PSPF) prevents client devices that are associated to an access point from inadvertently sharing files or communicating with other client devices that are associated to the access point. PSPF provides Internet access to client devices without providing other capabilities of a LAN. This feature is useful for public wireless networks like those installed in airports or on college campuses.
Note To prevent communication between clients associated to different access points, you must set up protected ports on the switch to which the wireless devices are connected. See the "Configuring Protected Ports" section for instructions on setting up protected ports.
To enable and disable PSPF using command-line interface (CLI) commands on the wireless device, you use bridge groups. You can find a detailed explanation of bridge groups and instructions for implementing them in this document:
•Cisco IOS Bridging and IBM Networking Configuration Guide, Release 12.2. Click this link to browse to the Configuring Transparent Bridging chapter: http://www.cisco.com/en/US/docs/ios/12_2/ibm/configuration/guide/bcftb_ps1835_TSD_Products_Configuration_Guide_Chapter.html
PSPF is disabled by default. To enable PSPF, follow these steps, beginning in privileged EXEC mode:
| |
Command
|
Purpose
|
Step 1
|
configure terminal
|
Enters global configuration mode.
|
Step 2
|
interface dot11radio {0}
|
Enters interface configuration mode for the radio interface. The 802.11g/n 2.4-GHz radio is radio 0.
|
Step 3
|
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