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QoS on the WSS Switch
The WSS 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. (For infor-
mation about using ACLs to change CoS, see “Using ACLs to Change CoS” on page 374.)
• If the WSS is forwarding a packet to an AP, WSS Software encapsulates the packet in an IP 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 WSS never changes the data packet’s IP ToS value.
• If the WSS is forwarding a packet through a tunnel to another WSS switch, WSS Software uses the same process
used for traffic to an AP. Generally, an WSS switch uses a tunnel to send user data to another WSS switch when the
user’s VLAN is configured on the other switch but not on the local switch.
• If the WSS is forwarding a packet on a wired interface that has an 802.1Q VLAN tag, the switch sets the packet’s
802.1p value based on the incoming QoS value.
• If the WSS 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.
