Nortel Networks 2300 manual Disabling or Reenabling WMM, WMM Priority Mappings

308Wi-Fi Multimedia

3WSS A examines the 802.1p and IP ToS information in the packet. If the interface on which the switch will forward the packet is part of a tagged VLAN, the WSS switch maps the IP ToS value of the tunnel header to the 802.1p priority field of the data packet. The packet is now marked as high priority at Layer 2 as well as Layer 3.

4The packet emerges from the network cloud between the WSS switches with the same priority information.

5WSS B receives the packet, examines the 802.1p and IP ToS information in the packet, and encapsulates the data packet in a tunnel packet for sending to the AP. The switch sets the IP ToS value in the tunnel header based on the data packet’s IP ToS value, or based on the 802.1p value if IP ToS is set to 0 in the data packet itself.

If the packet matches a permit ACL mapped to the outbound traffic direction on the AP port, Distributed AP, or user VLAN, and the ACL sets the CoS value, the tunnel header’s IP ToS value is set based on the CoS value in the ACL instead.

WSS B sends the encapsulated data packet to AP B.

6AP B receives the packet and maps the IP ToS value in the tunnel header to the Voice forwarding queue on the AP. The Voice queue has statistically more access to the air than the other queues, so the user’s voice traffic receives priority treatment.

Table 20 shows how WMM priority information is mapped across the network. When WMM is enabled in WSS Software, Nortel switches and APs perform these mappings automatically.

Table 20: WMM Priority Mappings

Service	IP					AP
		IP ToS	DSCP	802.1p	CoS Forwarding
Type	Precedence
						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

Disabling or Reenabling WMM

WMM is enabled by default on all radio profiles. To disable the feature on a radio profile, use the following command:

set radio-profile name wmm {enable disable}

When WMM is disabled, AP forwarding prioritization is optimized for SVP instead of WMM, and the AP does not tag packets it sends to the WSS. Otherwise, the classification and tagging described in “How WMM Works in WSS Software” on page 305 remain in effect.

320657-A