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Using the Bridging Option

Ubee DVW326 Advanced Wireless Voice Gateway Subscriber User Guide

•

March 2014

82

9.6

Using the Bridging Option

Use the

Bridging

option to configure the DVW326 to act as a wireless network bridge and

establish wireless links with other wireless access points. To establish a bridge, you need

to know the MAC address of the peer device. The peer device must be in wireless

bridging mode as well. The DVW326 can establish up to four wireless links with other

wireless access points. When wireless devices are in wireless bridging mode, they form a

wireless distribution system that allows computers in one LAN to connect to the

computers in the other LAN.

Caution

Avoid bridge loops when you enable bridging devices. Bridge loops cause broadcast traffic to

circle the network endlessly. This can degrade throughput and disrupt communications.

CWmin

CWmax

AIFSN

TXOP (b) Limit (usec)

TXOP (a/g) Limit (usec)

Discard Oldest First

Sets the time for the following fields:



CWmin

– Contention window minimum



CWmax

– Contention window maximum



AIFS

– Arbitration inter-frame space



TXOP

– Transmit opportunity



Discard Oldest First

– Removes oldest frame when set to

On.

EDCA STA Parameters

Allows you to prioritize wireless network traffic for receiving

terminals. Access categories are:



AC_BE

– Best Effort, medium throughput and delay. Most

traditional IP data is sent to this queue.



AC_BK

– Background, high throughput. Bulk data that

requires maximum throughput and is not time-sensitive is

sent to this queue (for example, FTP data).



AC_VI

– Video



AC_VO

– Voice

WMM TXOP Parameters

Allows you to prioritize wireless network traffic for wireless

multimedia transmit opportunities. Access categories are:



AC_BE

– Best Effort, medium throughput and delay. Most

traditional IP data is sent to this queue.



AC_BK

– Background, high throughput. Bulk data that

requires maximum throughput and is not time-sensitive is

sent to this queue (for example, FTP data).



AC_VI

– Video



AC_VO

– Voice

Short Retry Limit

Short Fallbk Limit

Long Retry Limit

Long Fallbk Limit

Max Rate in 500kbps

Defines how many times the MAC retries to send different types

of packets. If the number of retries reach their limit, the frame is

discarded.

Apply

Saves all changes.

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Steps

To configure the modem as a bridge:

1.

Click

Wireless

from the main menu.

2. Click

Bridging

from the left side menu. Field descriptions are listed below the screen

example.

9.7

Deploying and Troubleshooting the Wireless Network

Use the information in this section to help you understand, deploy, and troubleshoot your

wireless environments:



Understanding Received Signal Strength on page 83



Estimating Wireless Cable Modem to Wireless Client Distances on page 84



Selecting a Wireless Channel on page 87

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

Label

Description

Wireless Bridging

Enables or disables bridging.

Remote Bridges

Defines the MAC addresses of other wireless access points that

you want to establish a bridge to and from. These access points

must also have bridging enabled.

Apply

Saves all changes.

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Deploying and Troubleshooting the Wireless Network

Ubee DVW326 Advanced Wireless Voice Gateway Subscriber User Guide

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84

To determine the received signal strength, refer to

Using the Access Control Option on

page 78

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 access point (the

DVW326) 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 DVW326 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 14

if needed.

2.

Place the wireless client at around one meter (three feet) away from the DVW326.

3.

Obtain the

RSSI

value for the connected client. Refer to

Using the Access Control

Option on page 78

. 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

0.24dB / 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

Glass Window (not tinted)

2dB to 3dB

Double Pane Coated Glass

13dB

Bullet Proof Glass

10dB

Steel / Fire Exit Door

13dB to 19dB

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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.

Check the wireless signal strength and speed of the computer connected wirelessly to

the DVW326. Instructions for checking speeds are provided for both a Windows and a

Mac computer in the table below. If the wireless computer is not connected, refer to

Connecting a Wireless Device on page 13

.

Human Body

3dB

Trees (Note 2)

0.15dB / 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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1.8.1

Understanding the 2.4GHz Band

The DVW326 operates in the 2.4GHZ frequency band. The table below provides a

information about the 2.4GHz band.

Checking Wireless Signal Strength and Speed

Windows PC

Apple Mac

1.

Click the Wireless networking icon in the

system tray to display a list of available

wireless networks.

1.

Hold down the Option key and click on

the wireless icon (Airport) on the right

side of the top menu bar.

2. Click “Open Network and Sharing Center,”

then click “Wireless Network Connection.”

2. Information about the current wireless

connection appears below the SSID. If

you continue to hold the Option key and

hover over any network, information

about the connection is visible.

3. Review the speed and signal strength in

the Status window.

Band

2.4GHz

Channels

In the USA, channels 1-11 are used. There are 3 non-overlapping channels

(1, 6, and 11). Auto channel should be selected to ensure that the channel

with the least interference is used.

Standards

802.11b,g,n