Specifications

advantages of WLAN virtualization. For a more detailed look at this subject a link to a white
paper on WLAN virtualization follow the link below.
With Vport there is a “parent” BSS that is common to all clients for a given channel and ESS.
Just to be clear the clients never associate to the parent BSS when Vport is configured. The
parent BSS is used when load balancing is enabled which will be discussed later in this
guide.
http://www.merunetworks.com/pdf/whitepapers/
WP_increasing_reliability_of_virtualized_WLAN_0510_v2.pdf
Design Considerations AP300 VPort – Slow Clients
There are special considerations where Vport is used in the presence of slower clients. With
Vport each station gets their own beacon stream. Slower clients, in particular, 11b clients
beacon streams can take up an inordinate amount of airtime due to the slow data rate at
which they are transmitted.
Beyond the airtime utilization consideration there is the concept of an interference region (IR),
or the area that is consumed by a single transmission, thus preventing other clients from
successfully transmitting. With slower data rates the IR is considerably larger. With that in
mind there are a number of suggested guidelines when Vport and slower clients are in play.
The following illustration depicts relative airtime used by frames using different data rates.
Relative airtime utilization is represented by the horizontal bars to the right of each data rate.
The longer the bar, the greater the airtime utilization.
This next diagram shows how lower data rates can reach clients at greater distance from the
AP (and vice versa). The circles with the thinner line represent the distance that lower data
rate traffic can reach. The thicker lines represent higher data rate traffic.
BPG_11n_v1.0 | Page 11
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization