Wi-Fi Multimedia; How Wmm Works In Mss - D-Link DWS-1008 User Manual

DWS-1008 User's Manual
MSS supports Wi-Fi Multimedia (WMM). WMM provides wireless Quality of Service for
time-sensitive applications such as voice and video. WMM is a pre-standard version of IEEE
802.11e, provided by the Wi-Fi Alliance to enable vendors to provide interoperable multimedia
support before ratification of the standard.
WMM maps priority information between wired and wireless packets, so that high priority
traffic receives end-to-end high priority treatment through the network. WMM is enabled by
default and does not require any configuration. You can disable the feature on individual radio
profiles.
Note: MSS also can support non-WMM VoIP devices. However, to provide priority service to
non-WMM VoIP traffic, you must configure an ACL to set the CoS (Case of Service) for the
traffic. The AP maps this CoS value to a forwarding queue.

How WMM Works in MSS

DWS-1008 switches support WMM by tagging QoS information in packets. MSS classifies QoS
information in a packet received by the switch. MSS then tags the packet's QoS information
before forwarding the packet. Depending on the destination, MSS can set QoS information
by setting a packet's 802.1p value or by setting the IP ToS value in the IP tunnel header, if the
traffic is tunneled. MSS does not change the IP ToS value in the data packets themselves.
QoS on the DWS-1008 Switch
The switch obtains an inbound packet's QoS value from the packet's Layer 2 802.1p or Layer
3 IP ToS value. Depending on the destination, the switch maps the QoS information to other
parts of the packet before forwarding it. If a packet has both 802.1p and IP ToS information,
the switch sets QoS for the packet based on the IP ToS value.
However, if an ACL is mapped to the outbound traffic direction on the AP port, Distributed
AP, or user VLAN, the switch sets QoS based on the CoS value in the ACL, regardless of the
802.1p and IP ToS values in the packet.
If the switch is forwarding a packet to an AP, MSS encapsulates the packet in an IP
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tunnel, and marks the IP ToS value in the tunnel header based on the incoming QoS
value. This occurs for directly connected APs and for Distributed APs. The switch never
changes the data packet's IP ToS value.
If the DWS-1008 is forwarding a packet through a tunnel to another switch, MSS uses
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the same process used for traffic to an AP. Generally, a switch uses a tunnel to send
user data to another DWS-1008 switch when the user's VLAN is configured on the
other switch but not on the local switch.
If the switch is forwarding a packet on a wired interface that has an 802.1Q VLAN tag,
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the switch sets the packet's 802.1p value based on the incoming QoS value.
• If the switch is forwarding a packet to a non-tagged wired interface, and the traffic is not
tunneled, the switch does not set the data packet's 802.1p value.
D-Link Systems, Inc.

Wi-Fi Multimedia

Wi-Fi Multimedia
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