Overview of WMM (Wi-Fi Multimedia)
Multimedia
applications in a Wi-Fi network require Quality of
Service (QoS) functionality. QoS
enables Wi-Fi access points to prioritize traffic and
optimizes the way shared network resources are allocated among different
applications. Without QoS, all applications running
on different devices have equal opportunity to transmit data frames. That works
well for data traffic from applications such as web browsers, file transfers,
or email, but it is inadequate for multimedia applications. Voice over Internet
Protocol (VoIP), video streaming, and interactive
gaming are highly sensitive to latency increases and throughput reductions, and
require QoS.
To
meet this need, the Wi-Fi Alliance started
interoperability certification for WMM (Wi-Fi Multimedia)
as a profile of the upcoming IEEE 802.11e QoS
extensions for 802.11 networks. WMM defines
four access categories (voice, video, best effort, and background) that are
used to prioritize traffic so that these applications have access to the
necessary network resources. Additionally, WMM-enabled Wi-Fi
networks concurrently support legacy devices that lack WMM functionality. The
WMM best effort access category and legacy devices transmit with the same
priority.
Overview of MBM (Multimedia
Bandwidth Management)
Unlike the dial-up
connectivity that has bandwidth limit, in today’s application like peer-to-peer
file sharing, online game or VoIP services can easily
consume the network bandwidth. In order to prevent the saturation of the
network, ZyXEL has introduced MBM (Multimedia Bandwidth Management) that allows
the users to facilitate dynamic bandwidth control with easy deployment.
In addition to that, the delay, jitter or packet loss
when playing the online game with many players may hurt user’s experience.
Degraded network QoS will influence online game
player’s willingness to continue playing the game as they are less tolerant to
any network delay while a few second delays in the FTP transmission will not
have any significant negative impact on user’s feeling. The packets from the
online game service are normally very delay sensitive compared to packets on
FTP or Peer-to-Peer transmission that can tolerate a few seconds of delay. To
secure the network QoS, vendors have developed many
tools or soft wares; ZyXEL has launched the ATC (Automatic Traffic Classifier)
that will automatically classify the outgoing traffic (WAN) into three data
stream types--High, Middle, and Low class (Best Effort).
ATC (Automatic Traffic Classifier)
Let’s take a closer look at what
is ATC. ATC by definition will group the traffic into three data streams. Real
time packets such as VoIP or online service will be
granted a high priority that will be categorized in the high queue and
forwarded first. Non-real time packets normally are from applications such as
FTP or Bit Torrent applications will be granted a lower priority that will be
put in the middle or best-effort queue and forwarded after the real-time
traffic.
Scenario: In the ABC Company’s Lobby, employee using internal VoIP and guests surffing internet
There are
more and more companies provide their guests to surf internet in the lobby area
when they visit company and waiting for someone. If this company implement the Wi-Fi SIP phone for their internal
communication. How can they set up the wireless environment to let the guest
surf internet meanwhile ensure the internal Wi-Fi phone
quality.
In this scenario,
we’ll use one NWA-3100
to achieve this goal. The configuration in our device is quite easy. Just
follow the steps below.
Notes: Here
we assume both the Wi-Fi SIP phones and guests’
client laptops support Wi-Fi Multimedia(WMM).
Step 1
1.
Login
NWA-3100 Web Configurator.
2.
Click
WIRELESS on the left frame of page.
3.
And
then click SSID on the top of this
page.
4.
Select
the profile “Index 3” and then click the Edit
button.
Step 2
1.
Input
the SSID profile name: Inter-VoIP
2.
Input
this profile’s SSID: VoIP
3.
Select
WMM_VOICE from the OoS drop-down list.
4.
Click
the Apply button
Step 3
1.
Select
the SSID profile index 4 same as Step 1’s screen to edit it.
2.
Input
the SSID profile name: forGuest
3.
Input
this profile’s SSID: Guest
4.
Select
WMM_VOICE from the OoS drop-down list.
5.
Click
the Apply button
Step 4: Backup to to SSID
page, you’ll see the configuration like this.
Step 5: On the Wireless page
1.
Select
the MBSSID from the drop-down list
on Operation Mode.
2.
Select
the SSID profile index 3 and index 4
3.
Click
the Apply button
Now you have
done all the setting on NWA-3100.
Step 6: Wi-Fi Phone setting
For the Wi-Fi phone, you need to configure to let the Wi-Fi phone associate with the SSID = “VoIP”.
This can make the voice has the high priority then the data transmitted on
another SSID ( i.e. Guest)
Step 7: Guests’ Laptop Setting
The last
thing to is let the vistors’ laptop connect to
wireless network by using SSID = “Guest” !
Scenario 2: IF my Wi-Fi phone does not support Wi-Fi Multimedia(WMM), how can I
configure to allocate the bandwidth with the high priority (QoS)
for voice transmit?
Although your Wi-Fi
devices do not support WMM, our NWA-3100 provide another feature
to achieve the quality of service(QoS) – Automatic
Traffic Classfier(ATC).