Linksys Cloud Manager 2.0 – Access Point Capacity Planning Guide

Estimating Wireless Network Capacity

Even though there’s no software limit to how many WiFi clients an access point can connect to, there is a real limit that is determined by a few factors:

 
1.  How much bandwidth is allocated to each user for the application you want to support i.e., web browsing, VoIP, and video?  This will determine the total bandwidth needed and the max number of clients per access point.

2.  The total WiFi bandwidth available per access point is specified by the radio and antenna design.  For example, AC1750 means there’s a theoretical data rate of 1750 Mbps total WiFi bandwidth available, 1300 Mbps on 5 GHz, and 450 Mbps on 2.4 GHz.  Realistically, the estimated throughput available is
50% minus an additional 30% to account for WiFi overhead.

3.  For high-density areas with many clients, consider deploying additional access points with overlapping coverage to increase your capacity.  Consider using
20-40 MHz channels for 5 GHz, 20 MHz channels for 2.4 GHz and set wireless channels manually to ensure the least amount of wireless interference with other access points.  We highly recommend not using 80 MHz channels for 5 GHz and 40 MHz channels for 2.4 GHz unless you have complete control over the wireless environment.

Estimating Total Aggregate WiFi Bandwidth

To estimate the bandwidth needed, first determine which applications you need to support.  Choose the application with the highest bandwidth requirement as the worst-case scenario per client.

 
ApplicationThroughput
Web Browsing500 Kbps
Audio, VoIP128-320 Kbps
SD Video3 Mbps
HD Video5 Mbps
4K Video25 Mbps

Application Throughput x Number of Users = Aggregate WiFi Throughput

HD Video (5 Mbps) x 300 Users = 1500 Mbps


Estimating Total Access Points Needed

How many access points are needed is determined by the capacity and the coverage needed.  Using the Linksys LAPAC1750C as an example, we can determine:

 
1.  1300 Mbps on 5 GHz take 50% and minus an additional 30% for WiFi overhead = (1300 Mbps / 2) x 0.70 = 455 Mbps
2.  450 Mbps on 2.4 GHz take 50% and minus an additional 30% for WiFi overhead = (450 Mbps / 2) x 0.70 = 157.5 Mbps

Using HD video (5 Mbps) as a guide, you can determine the max number of clients that can be supported per radio per access point.
 
1.  455 Mbps / 5 Mbps (HD video) = 91 Users per access point on the 5 GHz radio
2.  157.5 Mbps / 5 Mbps (HD video) = 31 Users per access point on the 2.4 GHz radio

Make sure you consider any other traffic on other Wireless SSIDs that could contribute to the total WiFi bandwidth on an access point.  This will determine the minimum number of access points needed to satisfy the application throughput requirements.

For WiFi signal coverage requirements, add more access points beyond the above minimum needed according to an onsite wireless survey.


Enforcing Client Bandwidth Requirements

To prevent client overloading, there are three ways to enforce bandwidth policies:

 
1.  Restrict Total WiFi Bandwidth in a Wireless SSID
2.  Restrict Bandwidth per Client in a Wireless SSID
3.  Set Max Number of Concurrent Clients in a Wireless SSID

Restrict Bandwidth in a Wireless SSID

Setting this feature will help prevent a Wireless SSID or a Wireless Client from exceeding expected bandwidth requirements, ensuring other devices on the network have ample bandwidth access to the internet.  It can be found under Wi-Fi SSIDs > Settings > Bandwidth Limit.

 
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Consult your Application Throughput requirements to determine the best bandwidth setting per client.  Then place a Bandwidth Limit for the entire Wireless SSID according to how much speed you want to partition from your internet provider.  We recommend setting this to 80% or less of your entire internet connection speed to prevent reduced traffic speed and congestion.

Set Max Number of Clients in a Wireless SSID

Setting this feature will limit the number of clients that can connect to the 2.4 GHz radio and to the 5 GHz radio to prevent access point overloading.  The number set here will apply to both radios separately.  For example, setting the number to 30 will allow 30 clients to connect under the SSID on the 2.4 GHz radio and another 30 clients on the 5 GHz radio for a total of 60 clients.  It can be found under Wi-Fi SSIDs > Settings > Advanced.

Consult your Application Throughput requirements to determine the optimal number of clients for this setting.  This will help prevent new connections beyond the max number set and will force new clients to connect to another access point with fewer clients.


Other Helpful Settings

For the best performance, we also recommend enabling the following features:

 
1.  Wireless Client Isolation – This feature will prevent wireless clients from communicating with each other at the same SSID/access point.  It can be found under Wi-Fi SSIDs > Settings > Advanced.
 
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2.  DHCP/NAT Mode + Isolate Wireless Clients from Wired LAN – This feature will prevent Wireless Clients from communicating with other clients on the Wired LAN, including clients from other access points.  This creates a Double NAT scenario with your existing Router and could cause issues with online games or VPN clients.  Please disable this feature if it causes any issues with your applications.  It can be found under Wi-Fi SSIDs > Settings > Addressing.

3.  VLAN Tagging per SSID – Using this feature requires advanced VLAN configuration on a VLAN-aware Managed Switch and a VLAN-aware Router but offers more complete Layer 2 security and network segmentation.  This is highly recommended, but it requires an IT administrator or Consultant with advanced network design experience.  It can be found under Wi-Fi SSIDs > Settings > Addressing.

4.  802.11k Radio Resource Management – This feature will help clients roam to other access points quickly by providing extra channel and signal strength information to the client.  It can be found under Wi-Fi SSIDs > Settings > Advanced.

5.  802.11r Fast Roaming – This feature will help clients authenticate more quickly to other access points in the same network.  It can be found under Wi-Fi SSIDs > Settings > Advanced.

6.  Sticky Client Auto Disconnect – This feature will help disconnect clients that have low signal or high re-transmissions in order to force the client to connect to an access point with better signal strength.  This should only be used with two or more access points with overlapping coverage. 
Please disable this feature if you have issues with clients not connecting reliably.  
It can be found under Wi-Fi SSIDs > Settings > Advanced.

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