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3.8

Wireless

DDW3612 Subscriber User Guide

•

July, 2010

47

NPHY Rate

Set the Physical Layer (NPHY) rate. These rates are only

applicable when the

802.11n mode

is configured as

Automatic

.

802.11n Protection

If you select

Auto

, the DDW3611 will use Request to

Send/Clear to Send (RTS/CTS) to improve the performance in

802.11 mixed environments. If you select

Off

, the 802.11

performance will be maximized under most conditions, while the

other 802.11 modes (802.11b, etc.) will be secondary.

Multicast Rate

Specify the rate at which multicast packets are transmitted and

received on your wireless network.

Apply

Click to submit changes.

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DDW3612 Subscriber User Guide

•

July, 2010

3.8.5

Wireless - Bridging

The

Bridging

option allows you to configure the DDW3612 Wireless Cable Modem

Gateway 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, which must also be in wireless bridging mode. The DDW3612

Wireless Cable Modem Gateway can establish up to four wireless links with other

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

form a WDS (Wireless Distribution System) allowing the computers in one LAN to

connect to the computers in the other LAN.

Note:

Be careful to avoid bridge loops when you enable bridging devices. Bridge

loops cause broadcast traffic to circle the network endlessly, resulting in possible

throughput degradation and disruption of communications.

Note:

This feature is available when logged into the device using the MSO user

login. Refer to

page 4

for more information. Also, Firewall menu options are not

available when the device is in Bridge mode. Firewall options are available only

when the device is in NAT, NATRoute, or Route modes.

1.

Access the web interface. Refer to

page 7

, if needed.

2. Click the

Wireless

link from the top of the screen.

3. Click

Bridging

from the left side of the screen. The

Bridging

fields are explained

following this screen example.

Label

Description

Wireless Bridging

Select Enabled to enable bridging. Select Disabled to disable

bridging.

Remote Bridges

Enter the MAC address(es) of other wireless access points that

you want to establish a bridge to and from. Keep in mind that

these access points must also have bridging enabled.

Apply

Click to save all changes.

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Wireless

DDW3612 Subscriber User Guide

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July, 2010

49

3.8.6

Wireless - Wifi Multimedia

The

Wifi Multimedia

option allows you to configure QoS (Quality of Service) to ensure

the quality of service in wireless networks.

Wifi Multimedia

controls WLAN

transmission priority on packets to be transmitted over the wireless network. WMM

QoS prioritizes wireless traffic according to the delivery requirements of the individual

user and applications. Refer to

page 50

for more information on

Wifi Multimedia

.

Note:

This feature is available when logged into the device using the MSO user

login. Refer to

page 4

for more information.

1.

Access the web interface. Refer to

page 7

, if needed.

2. Click the

Wireless

link from the top of the screen.

3. Click

Wifi Multimedia

from the left side of the screen. The

Wifi Multimedia

fields

are explained following this screen example.

Label

Description

WMM Support

Select On or Off to turn on or off WMM support.

No Acknowledgement

Select On or Off to turn on or off the acknowledgement of data

frames. In QoS mode, frames to send can have two values:

QosAck and QosNoAck. Frames with QosNoAck are not

acknowledged, thus avoiding the retransmission of highly time-

critical data.

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DDW3612 Subscriber User Guide

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3.8.7

Additional Information - WiFi MultiMedia (WMM)

WMM QoS is a part of the IEEE 802.11e QoS enhancement to certified WiFi wireless

networks.

On wireless access points without WMM QoS, all traffic streams are given

the same access priority to the wireless network. If the introduction of another traffic

stream creates a data transmission demand that exceeds the current network

capacity, then the new traffic stream reduces the throughput of the other traffic

streams. A WMM QoS capability in a network may assign access categories (ACs) to

various streams of packets. The assigned AC of a stream of packets may depend on

the packets' priority, for example, as assigned by an application, and may be referred

Power Save Support

Select On or Off to turn on or off power savings. WMM Power

Save increases the efficiency and flexibility of data transmission.

Specifically, the wireless client device can "doze" between

packets to save power, while the wireless access point buffers

downlink frames. The application chooses the time to wake up

and receive data packets to maximize power conservation

without sacrificing Quality of Service.

EDCA-AP Parameters

Enhanced Distributed Channel Access - Access Point. In this

area of the screen, four Access Categories (ACs) are listed to

prioritize wireless network traffic. Refer to the next row below.

AC-BE

AC-BK

AC-VI

AC-VO

The Wi-Fi Multimedia feature prioritizes traffic according to four

access categories (ACs):

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

CWmin/CWmax/AIFSN

For each AC, set the following fields:

CWmin/CWmax

AIFS—Interframe Space

Back off Counter

TXOP (b) Limit

(usec)/TXOP (a/g) Limit

(usec)/Discard Oldest

First

Enter a TXOP limit. Each AC is assigned a Transmit Opportunity

(TXOP). A TXOP is a bounded time interval during which a

station can send as many frames as possible (as long as the

duration of the transmissions does not extend beyond the

maximum duration of the TXOP). If a frame is too large to be

transmitted in a single TXOP, it should be fragmented into

smaller frames. The use of TXOP reduces the problem of low

rate stations gaining an inordinate amount of channel time in the

legacy 802.11 DCF MAC. A TXOP time interval of 0 means it is

limited to a single MSDU or MMPDU.

EDCA STA Parameters

These settings are used for receiving terminals.

CWmin/CWmax/AIFSN

TXOP (b) Limit

(usec)/TXOP (a/g) Limit

(usec)

Refer to the rows above for definitions of these fields.

Apply

Click to save all changes.

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DDW3612 Subscriber User Guide

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July, 2010

51

to as a user priority (UP). An AC may include a common set of enhanced distributed

channel access (EDCA) parameters that may be used by QoS to contend for a

channel in order to transmit packets with certain priorities.

Different ACs may be associated with different power saving parameters. One such

power saving parameter may be, for example, the delivery mechanism used by an

access point (AP) to deliver packets to a station (STA) that is operating in a reduced

power mode. For example, one delivery mechanism may be the “legacy” power save

mechanism of the IEEE 802.11 standard: “ANSI/IEEE Std. 802.11, Information

technology—Telecommunications and information exchange between systems—Local

and metropolitan area networks—Specific requirements—Part 11: Wireless LAN

Medium Access Control (MAC) and Physical Layer (PHY) Specifications” (published

1999; reaffirmed June 2003). Another delivery mechanism may be the automatic

power save delivery (APSD) mechanism, e.g., unscheduled APSD (UAPSD) or

scheduled APSD (S-APSD), as defined in 802.11e. A QoS station (QSTA) may define

all or some of the ACs as trigger-enabled and/or delivery-enabled. A trigger- and

delivery-enabled AC may use UAPSD as the default delivery mechanism, whereas an

AC that is neither trigger- nor delivery-enabled may use the “legacy” power save

delivery mechanism.