HP Survivable Branch Communication zl Module powered by Microsoft Lync Planning and Design Guide 2011-02

2-23
Design Considerations
Planning Audio Quality
Table 2-17 shows how 802.1p values are mapped to queues on HP switches.
Traffic in the queue with the highest number is forwarded first.
Table 2-17. 802.1p Mapping to Queues
In summary, to ensure QoS in the LAN, complete three tasks:
■ Verify that the network infrastructure honors 802.1p settings. (By default,
HP switches do; refer to your switch’s documentation for specifics.)
■ Ensure that the VoIP traffic is classified with the correct priority.
■ When possible, place the VoIP traffic in a separate VLAN from data traffic,
which protects the VoIP traffic from broadcasts.
For the latter two tasks, you need to consider the devices that participate in
the Lync solution. The sections below explain more.
Microsoft Lync-Certified IP Phones. IP phones that run Microsoft Lync
2010 Phone Edition support Link Layer Discovery Protocol-Media Endpoint
Discovery (LLDP-MED) and Power over Ethernet (PoE). (IP phones are
sometimes called hard phones.) When the switch to which the phone connects
also supports LLDP-MED, this protocol automatically assigns the phone’s port
to the correct voice virtual LAN (VLAN), negotiates the correct PoE power
level (if PoE is used), registers the phone’s location, and so forth.
802.1p CoS Switch with
Eight Total
Queues
Switch
with Four
Total
Queues
Switch
with Three
Total
Queues
Switch with Two
Total Queues
1 1 1 1 1
2
2 1 11
0
3 2 21
3
4 2 21
4
5 3 32
5 6 3 3 2
6 7 4 3 2
7
8 4 32