HP Vm200 User Manual

							Wireless configuration
Radio configuration
5-11
Operating mode
Select the operating mode. Available options are: 
Access point and WDS bridge: Standard operating mode provides support for all 
wireless functions.
Access point only: Only provides AP functionality, WDS links cannot be created.
WDS bridge: Only provides WDS functionality. Wireless client stations cannot connect.
Monitor: Puts the radio in promiscuous mode (no transmissions). Both AP and WDS 
bridge functionality are disabled. Use this option for continuous scanning for rogue APs 
across all channels in all wireless modes. See the results of the scans on the 
Wireless > 
Rogue AP detection page.
 This mode also enables 802.11 traffic to be traced when using 
the 
Tools > Network trace command. 
Wireless mode
Select the mode that best supports the wireless client stations at your location.
Supported wireless modes are determined by the regulatory domain (country). Available 
options may include one or more of the following.
802.11n (5 GHz): (Pure 802.11n) Supports up to 300 Mbps in the 802.11n 5 GHz 
frequency band.
802.11n/a: (Compatibility mode) Supports up to 270 Mbps for 802.11n and 54 Mbps for 
802.11a in the 5 GHz frequency band.
802.11n (2.4 GHz): (Pure 802.11n) Supports up to 144.4 Mbps in the 802.11n 2.4 GHz 
frequency band.
802.11n/g: (Compatibility mode) Supports up to 130 Mbps for 802.11n and 54 Mbps for 
802.11g in the 2.4 GHz frequency band. Only use this setting when support for 802.11g is 
necessary.
802.11n/b/g: (Compatibility mode) Supports up to 130 Mbps for 802.11n, 54 Mbps for 
802.11g, and 11 Mbps for 802.11b in the 2.4 GHz frequency band. Only use this setting 
when support for 802.11b is necessary.
802.11b: Supports up to 11 Mbps in the 2.4 GHz frequency band.
802.11b/g: Supports up to 11 and 54 Mbps in the 2.4 GHz frequency band.
802.11g: Supports up to 54 Mbps in the 2.4 GHz frequency band.
802.11a: Supports up to 54 Mbps in the 5 GHz frequency band. 
						

							Wireless configuration
Radio configuration
5-12
NoteIn 802.11n (2.4 GHz) and 802.11n (5 GHz) modes, the V-M200 does not permit non-
802.11n clients to associate. Also in this mode, the V-M200 does not use protection 
mechanisms (RTS/CTS or CTS-to-self) to enable legacy APs to operate on the same 
frequency. This can potentially cause problems with legacy (802.11a/b/g) APs operating on 
the same channel, but provides the best throughput for the V-M200 and its 802.11n clients. 
In 802.11n/a, 802.11n/g, and 802.11n/b/g modes, the V-M200 permits both 802.11n and 
legacy clients (802.11a/b/g) to associate. The V-M200 uses protection mechanisms (RTS/CTS 
or CTS-to-self) when sending 802.11n data to prevent disruption to legacy (802.11a/b/g) 
clients associated on the same channel.
For more information, refer to 802.11n best practices on page 5-7.
Channel width
(Only applicable when Wireless mode includes some type of 802.11n support.)
(Only configurable when Wireless mode is set to 802.11n (5 GHz) or 802.11n/a. For all 
other 802.11n modes, Channel width is set to 20 MHz and cannot be changed.)
Select the Channel width that will be used for 802.11n users.
20 MHz: Sets channel width to 20 MHz.
Auto 20/40 MHz: Under most conditions this can double throughput by bonding 
adjacent channels to form a 40 MHz channel. This option reduces the number of 
unoccupied channels available to neighboring APs. 
NoteAlthough some 802.11n clients only support 20 MHz channels, they can still associate with a 
V-M200 configured for Auto 20/40 MHz.
Channel 
Select channel and frequency for wireless services. The channels that are available are 
determined by the regulations that apply in your country. 
Use the Automatic option to have the V-M200 select the best available channel. 
If setting the channel manually, for optimal performance when operating in 2.4 GHz modes, 
select a channel that is different from other wireless APs that operate in neighboring cells by 
at least by five channel numbers (25 MHz). For example, if another AP is operating on 
channel 1, set the V-M200 to channel 6 or higher. Select Wireless > Rogue AP detection, 
and then select Configure Access Point List to view a list of APs currently operating in 
your area.
When operating in 802.11a or 802.11n (5 GHz) modes, interference between APs is not a 
consideration as all channels are non-overlapping. 
						

							Wireless configuration
Detecting rogue APs
5-13
When Wireless mode is 802.11n (5 GHz) or 802.11n/a and Channel width is Auto 20/40 
MHz, the channel numbers in the Channel list include either a “(1)” or “(-1)” to their right. 
A “(1)” indicates that the 40 MHz channel is formed from the indicated channel plus the next 
channel. A “-1” indicates that the 40 MHz channel is formed from the indicated channel plus 
the previous channel.
With a 40 MHz Channel width in the 5 GHz band, channel selection and usage is as follows for 
the first four channels:  
NoteThe channel selected is the primary channel and the channel above or below it becomes the 
secondary channel. The AP beacon is transmitted only on the primary channel and all legacy 
client traffic is carried on the primary channel. 
Detecting rogue APs
You can use the Rogue AP detection feature to scan for other APs operating nearby and flag 
them as either authorized APs or rogue APs. This is useful for monitoring the installation of 
wireless access points in your company’s work areas to ensure that new APs (which could be 
a security risk if improperly configured) are not deployed without your knowledge. 
This feature can also be used to determine the operating frequencies of nearby APs for site 
planning purposes.
NoteScanning is temporarily disabled when a trace is active (Tools > Network trace page).
To obtain the best possible wireless performance (such as needed for voice applications), 
scanning should be disabled. To disable, clear the Repeat scan checkbox under Scan 
interval.
Scanning modes
The way in which the V-M200 performs scanning depends on the configuration of the wireless 
radio (Wireless > Radio page). The following scanning modes are possible:
Monitor mode: When the radio has its Operating mode set to Monitor, scanning 
occurs continuously. The scan switches to a new channel every 200 ms, sequentially 
covering all supported wireless modes and channels. Use this method to quickly obtain 
an overview of all APs in your area for site planning, or for initial configuration of the 
authorized access points list.
Channel selectedChannels used
36(1) 36+40
40(-1) 40+36
44(1) 44+48
48(-1) 48+44 
						

							Wireless configuration
Detecting rogue APs
5-14
Automatic channel: When the radio has its Channel set to Automatic, scanning is 
performed for all the channels in the currently selected Wireless mode when the V-M200 
starts up.
Background scanning: For any other radio configuration, scanning is controlled by the 
settings on the Rogue AP detection page. To enable scanning, select the Repeat scan 
checkbox and set the Scan interval. Scanning is performed for all the channels in the 
currently selected radio Wireless mode. One channel is scanned during each scan 
interval. By default, the scan interval is set to 600 seconds. This is done to minimize the 
impact on radio throughput.
Use this method to continuously view APs operating in your area while minimizing the 
effect on throughput.
Viewing scan results
To view the results of the latest scan, open the Wireless > Rogue AP detection page. For 
example:
To update scanning results, click the refresh button in your browser.
NoteRogue access points are not listed until you define at least one authorized access point as 
described under Creating a list of authorized access points on page 5-15. 
						

							Wireless configuration
Detecting rogue APs
5-15
Scanning for rogue APs
When the V-M200 discovers an AP during a scan it compares the MAC address of the AP 
against the list of authorized APs (which you must define). If the scanned AP does not appear 
in the list of authorized APs, it is displayed in the Rogue access points table.
If the V-M200 is in background scanning mode, it will scan all channels in the currently 
selected radio operating mode approximately once every two hours (assuming the default 
scan interval of 600 seconds). This provides for continuous background monitoring for rogue 
APs.
Creating a list of authorized access points
The easiest way to create this list is automatically. However, this requires that the authorized 
APs are already operating and have been found by a scan. If not, then the list can be defined 
manually.
To create the list
1.Under the Authorized access points table, click Configure Access Point List. 
2.Under Add access points, do the following for each access point you want to authorize:
If the access points you want to add appear in the All access points table:
1.Select the option Select from list of scanned access points.
2.Select the access point in the All access points table that you want to authorize.
3.Select Add. The MAC address for this access point is added to the Authorized 
access points table. 
						

							Wireless configuration
Viewing wireless information
5-16
To add access points that do not appear in the All access points table:
1.Select the option Manually configure. 
2.Specify the MAC address of the access point that you want to authorize. The 
MAC address must be in the following format: 12 hexadecimal numbers 
separated by colons, with the values “a” to “f” in lowercase. For example: 
00:03:520:a0:f01.
3.Select Add. The MAC address is added to the Authorized access points table.
3.Select Save to return to the Rogue AP detection page. The Authorized access points table 
will show all the new APs that you added, and they will no longer appear in the Rogue 
access points table.
Viewing wireless information
The V-M200 provides several pages where you can view information related to wireless 
operation.
Viewing all connected wireless clients
Select Wireless > Client connections. 
MAC address
The MAC address of the client station.
IP Address
The IP address assigned to the client station.
VLAN
The Ethernet VLAN assigned to the client station.
SSID
The SSID with which the client station is associated.
Authorized
Ye s : Client station has the right to transmit/receive traffic.  
						

							Wireless configuration
Viewing wireless information
5-17
No: Client station can only transmit/receive 802.1X packets. 
Filtered: Client traffic is blocked by the MAC filtering feature.
Authentication
Indicates how the client station was authenticated.
Association time
Indicates how long the client station has been associated with the V-M200.
Signal
Indicates the strength of the radio signal received from the client station. Signal strength is 
expressed in decibel milliwatt (dBm). The higher the number the stronger the signal.
Noise
Indicates how much background noise exists in the signal path between the client station and 
the V-M200. Noise is expressed in decibel milliwatt (dBm). The lower (more negative) the 
value, the weaker the noise.
SNR
Indicates the relative strength of client station radio signals versus the radio interference 
(noise) in the radio signal path.
In most environments, SNR is a good indicator for the quality of the radio link between the 
client station and the V-M200. A higher SNR value means a better quality radio link. 
						

							Wireless configuration
Viewing wireless information
5-18
Viewing wireless statistics for the radio
Select Status > Wireless. 
						

							Wireless configuration
Viewing wireless information
5-19
Wireless port
UP: Port is operating normally
DOWN: Port is not operating
Frequency
The current operating frequency.
Protocol
Identifies the wireless protocol used by the V-M200 to communicate with wireless users.
Mode
Current mode of operation.
Tx power
Current transmission power.
Tx packets
The total number of packets transmitted.
Rx packets
The total number of packets received.
Tx dropped
The number of packets that could not be transmitted. This can occur when the wireless 
configuration is being changed.
Rx dropped
The number of received packets that were dropped due to lack of resources on the V-M200. 
This should not occur under normal circumstances. A possible cause could be if many client 
stations are continuously transmitting small packets at a high data rate.
Tx errors
The total number of packets that could not be sent due to the following error: Rx retry limit 
exceeded.
Tx multicast octets
The number of octets transmitted successfully as part of successfully transmitted multicast 
MSDUs. These octets include MAC Header and Frame Body of all associated fragments.
Tx unicast octets
The number of octets transmitted successfully as part of successfully transmitted unicast 
MSDUs. These octets include MAC Header and Frame Body of all associated fragments.
Tx fragments
The number of MPDUs of type Data or Management delivered successfully; i.e., directed 
MPDUs transmitted and being ACKed, as well as non-directed MPDUs transmitted. 
						

							Wireless configuration
Viewing wireless information
5-20
Tx multicast frames
The number of MSDUs, of which the destination address is a multicast MAC address 
(including broadcast MAC address), transmitted successfully.
Tx unicast frames
The number of MSDUs, of which the destination address is a unicast MAC address, 
transmitted successfully. This implies having received an acknowledgment to all associated 
MPDUs.
Rx multicast octets
The number of octets received successfully as part of multicast (including broadcast) 
MSDUs. These octets include MAC Header and Frame Body of all associated fragments.
Rx unicast octets
The number of octets received successfully as part of unicast MSDUs. These octets include 
MAC Header and Frame Body of all associated fragments.
Rx fragments
The number of MPDUs of type Data or Management received successfully.
Rx multicast frames
The number of MSDUs, with a multicast MAC address (including the broadcast MAC 
address), as the Destination Address, received successfully.
Rx unicast frames
The number of MSDUs, with a unicast MAC address as the Destination Address received 
successfully.
Tx discards wrong SA
The number of transmit requests that were discarded because the source address is not equal 
to the MAC address.
Tx discards
The number of transmit requests that were discarded to free up buffer space on the V-M200. 
This can be caused by packets being queued too long in one of the transmit queues, or 
because too many retries and defers occurred, or otherwise not being able to transmit (for 
example, when scanning).
Tx retry limit exceeded 
The number of times an MSDU is not transmitted successfully because the retry limit is 
reached, due to no acknowledgment or no CTS received.
Tx multiple retry frames
The number of MSDUs successfully transmitted after more than one retransmission (on the 
total of all associated fragments). May be due to collisions, noise, or interference. Excessive 
retries can indicate that too many computers are using the wireless network or that 
something is interfering with transmissions.