Bridge GUI Guide: Network Configuration
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3.8 QoS Implementation
The Bridge supports Quality of Service (QoS) expediting for
wireless traffic according to the WMM® (Wi-Fi Multimedia)
subset of the IEEE standard 802.11e,
QoS for Wireless LAN
,
and for Ethernet traffic according to the IEEE standard 802.1p,
Traffic Class Expediting
.
The Bridge marks traffic that contains 802.1p user-priority tags
with the associated QoS priority level. The default mapping of
priority tags to priority queues conforms to IEEE standard
802.1D, MAC Bridges, Annex G, but is user configurable (see
below). Traffic received without user-priority tags is marked for
Medium
(or
Best Effort
) QoS handling.
Ethernet QoS
On Ethernet, QoS tags are conveyed as part of the VLAN tags
that can be included in packet headers. If the Bridge is
configured to use VLANs, it will apply the user-priority values in
the VLAN tags of the traffic it receives according to the
mapping specified on
Configure
->
Ethernet Settings
.
The Bridge can send 802.1p user-priority tags over Ethernet
only when
VLAN Mode
is
Enabled
(Section 3.9) and only over
ports with a VLAN
Switching Mode
of
Trunk
since these are the only conditions under which the Bridge
sends VLAN-tagged packets.
When VLANs are disabled, the Bridge drops regular VLAN
traffic but accepts specialized
priority-tagged packets
in order
to support Ethernet QoS exclusive of a VLAN implementation.
Priority-tagged packets are those which include a VLAN tag
with a VLAN ID of zero (or null-value VLAN ID). The Bridge
sorts this traffic into QoS priority queues according to the user-
priority information contained in the VLAN tag. The Bridge
cannot send priority-tagged packets.
The Bridge’s per-port QoS override function (Section 3.7.7)
overrides any priority tagging information in the traffic on that
port, marking all traffic on the port for sorting into the specified
QoS priority queue.
Wireless QoS
When enabled on the BSS, WMM Quality of Service is in effect
for bridge links, the connections formed between Bridge radio
BSSs with
Wireless Bridge
Enabled
NOTE:
To deter-
mine/configure
WMM QoS capability
for a given device, con-
sult its documentation.
QoS is negotiated individually for devices connecting to a
WMM-enabled BSS configured to provide wireless access
(Section 3.3.4). If the connecting device supports and is
enabled for WMM QoS, the Bridge prioritizes traffic for the
device according to its priority tags. Traffic from devices that do
not send priority tags is marked for
Medium
(or
Best Effort
) QoS
handling.