Cisco Cisco 5520 Wireless Controller Libro bianco
Cisco vs Aruba Wireless Controllers
16
DR150602D
Copyright © Miercom 2015
18 June 2015
Wi-Fi is a shared medium. When APs select an overlapping channel, the APs and clients have to
share the airtime on that overlapping channel. This means that when one AP is transmitting data
to the client, the other APs on the same channel will have to pause their traffic communication
and wait till the first AP has finished the transmission. This goes in a round-robin fashion with
each AP getting an airtime to send data to the respective clients. More the overlapping, more the
waiting period for the APs. As the overlapping channel gets more crowded, the APs tend to have
higher retries for a successful data transmission.
With heavy overlapping of channels as seen in Aruba’s 40-MHz channel selection below, the
overall performance of the network tends to reduce as the co-channel interference and the
number of retransmissions goes up.
share the airtime on that overlapping channel. This means that when one AP is transmitting data
to the client, the other APs on the same channel will have to pause their traffic communication
and wait till the first AP has finished the transmission. This goes in a round-robin fashion with
each AP getting an airtime to send data to the respective clients. More the overlapping, more the
waiting period for the APs. As the overlapping channel gets more crowded, the APs tend to have
higher retries for a successful data transmission.
With heavy overlapping of channels as seen in Aruba’s 40-MHz channel selection below, the
overall performance of the network tends to reduce as the co-channel interference and the
number of retransmissions goes up.
40-MHz Channel Selection Visual Representation
40-MHZ CHANNEL WIDTH SELECTION TEST
VENDOR
NUMBER OF OVERLAPPING APS
CHANNELS OVERLAP PERCENTAGE
CISCO
2
40%
ARUBA
5
100%
CISCO RRM 40-MHz
ARUBA ARM 40-MHz
Source: Miercom June 2015
Source: Miercom June 2015