3Com WX2200 3CRWX220095A Switch User Manual

WMM QoS on the WX Switch
MSS performs classification on ingress to determine a packet’s CoS value.
This CoS value is used to mark the packet at the egress interface.
The classification and marking performed by the switch depend on
whether the ingress interface has an 802.1p or DSCP value other than 0,
and whether the egress interface is tagged or is an IP tunnel.
The mappings between DSCP and CoS values are configurable. (See
“Changing CoS Mappings” on page 344.) 802.1p and CoS values map
directly and are not configurable. DSCP 0 of the DSCP-to-CoS map is
reserved. 802.1p determines CoS for packets with DSCP 0. CoS 0 of the
CoS-to-DSCP map is also reserved. CoS 0 packets are marked with DSCP 0.
Table 27 shows how WMM priority information is mapped across the
network. When WMM is enabled, 3Com switches and MAPs perform
these mappings automatically.
You can use static CoS to assign the same CoS value to all packets for a
specific SSID. The static CoS value is assigned on the MAP, in both traffic
directions (from the client to the WX and from the WX to the client). (For
information, see “Configuring Static CoS” on page 343.)
Table 27 WMM Priority Mappings
Type IP Precedence IP ToS DSCP 802.1p CoS
0 0 0 0 0 0 Background
3 3 0x60 24 3 3
1 1 0x20 8 1 1 Best Effort
2 2 0x40 16 2 2
4 4 0x80 32 4 4 Video
5 5 0xa0 40 5 5
6 6 0xc0 48 6 6 Voice
7 7 0xe0 56 7 7