General Guidelines - Nortel 2360 Configuration Manual

General guidelines

Nortel recommends that you follow these guidelines for any wireless VoIP implementation:
• Ensure end-to-end priority forwarding by making sure none of the devices that will forward voice traffic resets IP
ToS or Diffserv values to 0. Some devices, such as some types of Layer 2 switches with basic Layer 3 awareness,
reset the IP ToS or Diffserv value of untrusted packets to 0.
WSS Software uses IP ToS values to prioritize voice traffic. For example, when an AP receives traffic
from its WSS, the AP classifies the traffic based on the IP ToS value in the IP header of the tunnel that is
carrying the traffic. By default, the WSS marks egress traffic for priority forwarding only if WMM is
enabled and only if the ingress traffic was marked for priority forwarding. If another forwarding device in
the network resets a voice packet's priority by changing the IP ToS or Diffserv value to 0, the WSS does
not reclassify the packet, and the packet does not receive priority forwarding on the AP.
• For WMM-capable devices, leave WMM enabled.
• For SVP devices, change the QoS mode to svp. You also need to disable IGMP snooping, and configure an ACL
that marks egress traffic from the voice VLAN with CoS value 7. (See
phones" (page 437)
For other types of non-WMM devices, you do not need to change the QoS mode, but you must configure
an ACL to mark the traffic's CoS value. This section shows examples for configuring VoIP for devices
that use TeleSym, and for Avaya devices.
Table 5 shows how WMM priority information is mapped across the network. When WMM is enabled in WSS
Software, WSSs and APs perform these mappings automatically.
Service
IP Precedence IP ToS
Type
0 0
3 3
1 1
2 2
4 4
5 5
6 6
7 7
You must map the ACL to the outbound traffic direction on an AP port, Distributed AP, or user VLAN. An ACL can set
a packet's CoS only in these cases.
You can enable legacy VoIP support on a VLAN, port group, port list, virtual port list, Distributed AP, or user wildcard.
You do not need to disable WMM support.
for complete configuration guidelines.)
Table 5: WMM priority mappings
0
0x60
0x20
0x40
0x80
0xa0
0xc0
0xe0
Nortel WLAN—Security Switch 2300 Series Configuration Guide
Configuring and managing security ACLs 435
"Enabling SVP optimization for SpectraLink
DSCP 802.1p CoS
0 0 0
24 3 3
8 1 1
16 2 2
32 4 4
40 5 5
48 6 6
56 7 7
AP
Forwarding
Queue
Background
Best Effort
Video
Voice