NETWORK INFRASTRUCTURE Network Topologies : no two networks are the same. The following are tips for configuring a Wi-Fi collaboration gateway to meet specific goals. • Virtual Local Area Networks (VLAN) : Placing Wi-Fi collaboration gateways on dedicated VLANs allows guest users and in-house users to collaborate seamlessly, while enabling network administrators to invoke firewall routing rules to control how much access guests from outside of the organization have to the enterprise network. Routing rules can isolate in-house users on the enterprise LAN and guest users on the gateway VLAN (Figure 5). • Air Gap : For sites that must maintain the highest level of network separation, an air-gapped solution could be the best option. By using two Wi-Fi collaboration gateways, one on the internal enterprise network and one on the dedicated guest network, there is no direct data connection point between the two networks. When in-house users need to collaborate with guest users, they would join the guest network. Firewalls in both the enterprise internal network and the guest network allow administrators to invoke routing rules to control how much access guests from outside of the organization have to both networks (Figure 6). REAL-WORLD WI-FI SIGNAL PROPAGATION Many things can impact the coverage of RF signals: absorption, scattering, reflection, diffraction, and refraction. This distorts the signal and creates multi- path signal propagation, which can impact performance. The 2.4 GHz Wi-Fi band uses 11 overlapping channels, each with 20 MHz bandwidth. Only three of those channels are non-overlapping, as shown in Figure 7 (this applies to channel assignments in North America; it is different in other regions of the world). Wi-Fi collaboration gateways placed more than 656 ft (200 m) apart are considered sparsely deployed and channel selection for the units is not critical since their signals do not reach the other units. Units placed closer together than this are considered densely deployed and the channels for each unit should be set
superimposed on the site floorplan, and recommend wireless access point placement. Key elements of an RF site survey are: • Accurately scaled floorplan of the facility (electronic format to upload into site survey apps). • In-person walkthrough (to note any floor plan discrepancies and/or large metallic furnishings that might interfere with signals). • Assess current infrastructure (i.e., WAP locations, network closets, wired network access points, current network architecture, network switch capabilities). • Determine area(s) requiring wireless AV coverage and assign tentative access points (i.e., meeting rooms, offices, classrooms/lecture halls, auditoriums). • Use a site survey app to map the RF environment (place test access points and walk the facility using the app to gather data on data rates, signal strength, active connections, etc.). • Refine access point locations based on readings obtained. • Record results.
so that adjacent devices are not on the same channel. A common 2.4 GHz setup is shown in Figure 7 using the three non-overlapping channels 1, 6, and 11. The 5 GHz Wi-Fi band uses 24 non-overlapping 20 MHz wide channels, and the 6 GHz band uses 59 non-overlapping 20 MHz wide channels. More non‑overlapping channels provide less chance for interference, making these bands a better choice for
dense deployments. The 5 GHz and 6 GHz bands add another tradeoff because they allow 20 MHz channels to be merged to create channels with bandwidths of 40, 80, or 160 MHz. Wider bandwidths allow higher data rates and lower latency, making them attractive for AV applications. However, merging channels means fewer non-overlapping channels, as the table in Figure 7 shows. Fewer
FIGURE 5 . Network topology with dedicated Wi-Fi collaboration gateway VLAN. Source: Extron
FIGURE 4 . Wi-Fi WLAN site survey apps provide precise analysis of network connection parameters (e.g., SSID, encryption, channel, signal level heat maps).
FIGURE 6 . Network topology with two air gapped Wi-Fi collaboration gateways. Source: Extron
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