Assessment Using Netiq Vivinet Assessor - Avaya Communication Server 1000 Installation And Commissioning Manual

Planning
the AP view, you can predict the APs that are likely to be the primary choice of voice devices
to use given their location. You can also predict where the handoff to another AP (and which
AP) can occur for a moving user.
Perform resiliency planning through the AP reachability view. This view presents a color-
coded visualization of the number of reachable APs from each point in the network. Locations
where the tool detects one AP, locations where the tool detects two APs, locations where the
tool detects three APs, and so on, are marked in distinct colors. With this visualization, you
can see where the network is vulnerable to a single point of failure. It is preferable to have at
least two APs that are capable of offering coverage to every point in the building.
You can also use the AP reachability view to perform location service planning. A minimum of
three APs must be reachable for triangulation to be effective. Therefore, use the AP reachability
feature to verify a consistent 3+ AP coverage across the building.
Location capabilities have a number of client dependencies, so verifying triangulation coverage
is more complex than it appears. There are two main location-solution types:
• those that use the client to collect information about the APs in the network (client-
based location)
• those that use the APs to collect information about the client (network-based location)
Both location-solution types use a form of triangulation to compute the location of the device.
Depending on the power level of the AP, it can sometimes hear devices that it cannot transmit
to. These factors combined create the following two scenarios:
• It is difficult to calibrate network-based solutions by using a laptop running the site survey,
because APs can sometimes hear clients that cannot hear the AP. If AP transmission
power levels are not at a maximum, they can hear clients over a greater distance than
their own transmissions can travel. This scenario can cause the site survey application
to underestimate the number of APs that can participate in triangulation.
• Client-based solutions cannot triangulate APs that are not detectable because their power
is lower. But the site survey application can accurately reflect the number of APs that can
be used for triangulation.

Assessment using NetIQ Vivinet Assessor

The Network Health Check is probably the most critical step toward ensuring a smooth rollout
for any VoIP deployment. This statement applies even more so to VoWLAN, because a WLAN
is a more challenging QoS environment than modern wired networks.
The NetIQ Vivinet Assessor 3.0 or later is the tool of choice for network health checking.
(Previously NetIQ Chariot, now an Ixia product, was recommended for network health
checking.) This product uses a laptop (for WLAN testing for WLAN mobility) as a voice-traffic
generation and analysis tool. You can configure several nodes in various parts of the network,
to simulate calls to and from those areas. Each node simulates call volumes through traffic
generation so that you can stress-test access links, backbones, and WAN links as necessary.
58 Avaya WLAN IP Telephony Installation and Commissioning November 2010