3Com WXR100 3CRWXR10095A WMM QoS on the WX Switch, WMM Priority Mappings, Service Forwarding Type

336CHAPTER 16: CONFIGURING QUALITY OF SERVICE

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.

Table 27 WMM Priority Mappings

							MAP
Service							Forwarding
Type	IP Precedence	IP ToS	DSCP	802.1p	CoS		Queue
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

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.)