Technical data

DATA CENTER and CAMPUS NETWORKS DEPLOYMENT GUIDE

Deploying Brocade Networks with Microsoft Lync Server 2010 38 of 52

Figure 11 Network with associated latencies.

Voice calls were made using (1) the soft clients, (2) the Polycom CX700 phones, and (3) High Definition

video calls:

1. From Seattle to all the remote sites

2. From San Francisco to all the remote sites

3. From New York to all the remote sites

4. From Austin to all the remote sites

5. Three conference calls among all the sites using (a) soft clients, (b) all Polycom phones, and

Test Results

The key metric in determining the success of the tests was the Mean Opinion Score (MOS). In most cases the

average MOS score was greater than 4; that is, between good and excellent. As expected, when the packet loss

was increased above 25 percent across the high-latency links, call quality started to diminish, which reduced the

MOS score. However, when packet loss was less than 25 percent, call quality was clear without any type of

noticeable degradation. The Polycom CX600 produced a better voice experience than the soft clients, due to the

hardware offloading.

HD video quality saw the biggest impact when packet loss was greater than 15 percent. When tests were conducted

with 10 percent packet loss and 55 ms latency, the HD video experience was very good, with a MOS score of 3.93.

The boundary for Microsoft Lync Server 2010 was 5 percent packet loss, thus a big improvement was seen for

HD video.

The latency used during the tests did not have an impact on voice calls. Even during the tests between New York and

Austin, which had a total latency of 75 ms, call quality was excellent.