3com WX1200 3CRWX120695A Manuel D’Utilisation

You also can use ACLs to override marking for specific packets. Configure 
ACEs that use the dscp option to match on ingress DSCP value, and use 
the cos option to mark CoS. A CoS value assigned by an ACE overrides 
the internal CoS value. (For information, see “Using ACLs to Change 
CoS” on page 399.)

MAPs use forwarding queues to prioritize traffic for wireless clients. 

For a packet received by the MAP from a client, the MAP classifies the 
packet based on the service type in the 802.11 header and maps the 
service type value to an internal CoS value. The MAP then marks the 
DSCP value in the IP tunnel header to the WX switch based on the 
internal CoS value.

For a packet received from a WX switch and addressed to a client, the 
MAP classifies the packet by mapping the DSCP value in the IP tunnel 
header to an internal CoS value. The MAP then assigns the packet to a 
forwarding queue based on the internal CoS value. The MAP also marks 
the service type in the 802.11 header based on the internal CoS value.

A MAP uses the DSCP-to-CoS and CoS-to-DSCP mappings of the WX 
switch that is managing it. If you change mappings on a WX switch, the 
change also applies to the MAP. Likewise, if a MAP changes to another 
WX switch (for example, after a MAP restart), the MAP uses the 
mappings in effect on the new WX.

If the use-client-dscp option is enabled for a service profile, WMM QoS 
is ignored, and the QoS level is classified based on the DSCP value. 
802.11 data packets without WMM are classified as QoS level 0 unless 
static CoS is enabled or the use-client-dscp option is enabled.

Table 28 lists the default mappings between a MAP’s internal CoS values 
and its forwarding queues. 

Table 28   Default CoS-to-MAP-Forwarding-Queue Mappings

1 or 2

Background

0 or 3

Best Effort

4 or 5

Video

6 or 7

Voice