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6.4

Deploying and Troubleshooting the Wireless Network

This section provides the following information to help you understand, deploy, and

troubleshoot your wireless environments:



Understanding Received Signal Strength on page 68



Estimating Wireless Cable Modem to Wireless Client Distances on page 68



Selecting a Wireless Channel on page 70

MAC Addresses

Defines the MAC addresses. Note: You may cut and paste

MAC addresses from the connected clients list at the bottom

of the screen.

Apply

Saves changes when clicked.

Connected Clients

Lists wireless clients currently connected listed by MAC

address.



MAC Address

– Displays the MAC addresses entered in

the MAC Addresses field (see above).



Age(s)

– Displays the duration since the wireless client’s

polled values were sent to the device. The values include

all information shown on this screen. The lower the

number, the more current its data.



RSSI(dBm)

– Displays the received signal strength from

the device to the wireless cable modem. This value is

commonly used to assist in troubleshooting wireless

performance issues. A signal strength between 0dBm

and -65dBm is considered optimal. Levels of -66dBm and

lower (for example, -70, -80, etc.) have a downward

impact on wireless data throughput. Refer to

Deploying

and Troubleshooting the Wireless Network on page 67

for

more information.



IP Address

– Displays the IP address assigned to this

wireless client.



Host Name

– Displays the host name of the wireless

client.



Mode

– Indicates the applicable 802.11a/b/g/n standard

used by the connected client device.



Speed (kbps)

– Displays the maximum theoretical link

speed negotiated

between the wireless gateway and the

client, not including the overhead associated with

encryption, and so on.

For example, actual speeds with

WEP encryption enabled a

re typically less than half of the

negotiated link speed. TKIP encryption can also affect

performance. AES is the most efficient and secure with

the highest throughput possible. You can disable WMM if

throughput on some client adaptors is adversely affected.

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Description

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Understanding Received Signal Strength

Received signal strength (RSSI) is measured from connected wireless client devices to

the wireless cable modem. This value can significantly impact wireless

speeds/performance. It is determined by:



Materials (for example, open air, concrete, trees)



Distance between wireless clients and the wireless cable modem



Wireless capabilities of the client devices

To determine the received signal strength, refer to

Using the Access Control Option on

page 65

and review the

RSSI

value. A receive signal strength indicator between 0 to -64

dBm is considered optimal. Levels of -67dBm and lower (for example, -70, -80, etc.) have

a downward impact on wireless data throughput.

Estimating Wireless Cable Modem to Wireless Client Distances

The information in this section helps you to determine how far a wireless cable modem

can be placed from wireless client devices. Environmental variances include the

capabilities of wireless clients and the types of material through which the wireless signal

must pass. When the wireless cable modem and wireless clients reach the distance

threshold between each other, network performance degrades.

Steps

To determine wireless cable modem placement:

1.

Connect a wireless client to the wireless cable modem. Refer to

Connecting Devices to

the Network on page 12

if needed.

2.

Place the wireless client at around one meter (three feet) away from the wireless cable

modem.

3.

Obtain the

RSSI

value for the connected client. Refer to

Using the Access Control

Option on page 65

. This value is used in the formula further below.

4.

Use the following table to determine what materials the wireless signal must travel

through to reach the desired wireless coverage distance.

Attenuation Considerations at 2.4GHz

Material

Attenuation

Connector/Cable

3.5dB

Free Space

.24dB / foot

Interior Drywall

3dB to 4dB

Cubicle Wall

2dB to 5dB

Wood Door (Hollow/Solid)

3dB to 4dB

Brick, Concrete Wall (Note 1)

6dB to 18db

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5.

Use the attenuation value from the materials table above in the following formula:

Formula:

(Transmit Power,

use -30dBm

)

–

(Receiver Sensitivity,

use RSSI value

)

=

Allowable Free Space Loss

Allowable Free Space Loss

÷

Materials Attenuation Value

=

Optimal Distance in Feet Between the Cable Modem and a Wireless Client

Example:

(-30dBm)

-

(-67dBm)

=

37dBm (allowable free space loss for a 54Mbps

connection)

37dBm

÷

.24db/foot (for open space)

=

154.16 feet

6.

Once you know the optimal feet distance between individual wireless clients and the

wireless cable modem, you may resolve and prevent some performance issues.

7.

To check the wireless signal strength and speed, use the following steps for a

Windows computer connected wirelessly to the wireless cable modem. If the wireless

computer is not connected, refer to

Connecting a Wireless Device on page 13

.

a.

Double-click the Wireless networking icon in the system tray.

Glass Window (not tinted)

2dB to 3dB

Double Pane Coated Glass

13dB

Bullet Proof Glass

10dB

Steel / Fire Exit Door

13dB to 19dB

Human Body

3dB

Trees (Note 2)

.15dB / foot

Note 1

: Different types of concrete materials are

used in different parts of the world and the thickness

and coating differ depending on whether it is used in

floors, interior walls, or exterior walls.

Note 2

: The attenuation caused by trees

varies significantly depending upon the shape

and thickness of the foliage.

Attenuation Considerations at 2.4GHz

Material

Attenuation

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b. Review the speed and signal strength in the Status window.

Selecting a Wireless Channel

You may need to change the wireless channel on which the wireless cable modem

operates when you are in computing, test, and other environments where several wireless

access points may be operating in the 2.4Ghz range.

In some cases, you may want to segment your wireless traffic where a group of devices

operates on one channel and another group operates on another channel, and so on. This

is done by configuring the channel on each wireless access point individually (if you have

multiples). If you have control over only one wireless device in an environment where

there may be several, you can change the wireless channel on your device to one that is

not heavily used.

Note

To change the wireless broadcast channel, refer to

Using the Wireless Radio Option on

page 57

.

The following diagram displays the channels available in the Americas. Each available

channel is 22Mhz wide. Since channels overlap, it is best to choose channels that have

the least overlap (typically 1, 6, and 11 in the Americas, and 1, 5, 9, and 13 in Europe).

Overlapping channels can cause wireless network performance issues.

Source: Wikipedia.org, and IEEE article IEEE 802.11n-2009

Ubee DVW3201B Advanced Wireless Voice Gateway Subscriber User Guide

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7

Understanding the Firewall Menu

This chapter provides instructions to configure the DVW3201B firewall to control what

types of traffic are allowed on your network. The firewall can block certain Web-oriented

cookies, java scripts, and pop-up windows. It is highly recommended the Firewall is left

enabled at all times to protect against denial of service (DoS) attacks. Refer to

Using the

Basic Option on page 77

to block Internet access to specific sites.

Note

: Firewall menu options are not available when the device is in Bridge mode.

Topics

See the following topics:



Using the Content Filter Option on page 71



Using the Event Log Option on page 73



Using the Remote Log Option on page 74

Steps

To access the firewall menu:

1.

Access the Web interface. Refer to

Accessing the Web Interface on page 17

.

2. Click the

Firewall

link from the top of the screen.

7.1

Using the Content Filter Option

The

Content Filter

option allows you to block certain Web-oriented cookies, java scripts,

and pop-up windows.

Steps

To filter Web content:

1.

Click the

Firewall

link from the top of the screen.

2. Click

Content Filter

from the left side of the screen. The

Content Filter

fields are