Cisco Cisco Catalyst 6000 Multilayer Switch Feature Card MSFC2 White Paper

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Bringing It All Together

Consider a high-density WLAN deployment in two rooms that together are 26,000 square feet, Figure 15. Room A

has seating for 1,450 and room B has seating for 1,500. Both rooms are separated by a double air-gaped

temporary wall, which provides good RF attenuation. The design goal is to provide coverage for the participants,

assuming a 25 percent duty cycle. The focus is on 2.4 GHz coverage, since this is the critical resource for most all

PDAs and several tablet models. 5 GHz exhibits similar advantages in the denser room and room B had far more

happy 5 GHz users simply because propagation distances were less overall between AP and clients.

Figure 15. Two-Room High-Density WLAN

Room A has a total of six APs deployed. Two APs have directional antennas used from the sides, two APs with

internal antennas are positioned at the front, one internal antenna AP is positioned at the rear of the room, and

one internal AP is floor mounted to fill in for a shadow behind a pillar in the room. Power levels are set to 11 dBm

and result in good coverage levels for the room. Minimum data rates are set to 9 Mbps. BandSelect and Cisco

ClientLink are enabled.

Room B has a total of 12 APs deployed. Eight are positioned under the seating in the room. Two APs are at the

rear and two APs are in the front of the room. Power levels were reduced to 5 dBm. Minimum data rates were held

at 12 Mbps, BandSelect and Cisco ClientLink were enabled.

These deployments resulted in significantly different user experiences in each room:

●

Room A did not have an even balance of clients on all six of the APs, with a pronounced number staying on

the AP that was near the entrance to the room indicating that they never roamed. Performance was

moderate, but there were no user complaints.

●

Room B had a much more balanced load distributed across all the APs in the room and performance was

significantly better, as indicated by the throughput observed in the room and on the network supplying it.

Reviewing the duty cycle in the two rooms from the same period, there was a significant difference in the RF

conditions between room A and B. Over a 10 minute period, the duty cycle for channels 6,11 in Room A averaged

near 100%, and channel 1 exhibited spikes of 100%, as shown in Figure 16.