Meru Technical Note - What is Virtual Cell Overflow and how to configure the same ?
What is Virtual Cell Overflow and how to configure the same ?
Scope
KB ARTICLE TYPE: Configuration
RELATED PRODUCTS: NA
RELATED SOFTWARE VERSIONS: All versions
KEYWORDS: vcell/ess overflow
Solution
This feature, called Vcell Overflow, works by pairing a Virtual Cell ESS with a non-Virtual Cell ESS. The overflow ESS automatically inherits the parameters of the Virtual Cell ESS (except the setting for Virtual Cell). The non-Virtual Cell ESS is not used unless the Virtual Cell ESS is maxed-out; when this happens, the Virtual Cell ESS overflows into the other ESS as needed. The two ESS Profiles share same SSID so that clients seamlessly move back and forth. The overflow decision is based on the percentage of airtime spent on beacons crossing a threshold; when the percentage reaches 50%, clients start to overflow
When to Use Virtual Cell Overflow?
This feature is designed for a high density deployment and provides a solution for bottlenecks caused by transmitting beacons. Virtual Cell Overflow is useful in these situations:
• Beacon overhead has become very high due to the legacy b devices.
• A very dense network is consuming a lot of airtime with beacons.
Be aware that Virtual Cell Overflow has these tradeoffs:
• Trade-off between mobility and performance
• Trade-off between density and performance
• Not a solution to get good performance for overflow clients
Configure Virtual Cell Overflow with the Web UI
To set up Virtual Cell Overflow from the Web UI, follow these steps:
1. Create a Virtual Cell ESS.
Be sure that the setting for Virtual Cell is set to On.
2. Create a non-Virtual Cell ESS.
Be sure that the setting for Virtual Cell is set to Off. Make this an Overflow
ESS with the setting Overflow for; select the ESS you created in Step 1. This
overflow ESS automatically inherits the remaining parameters of the Virtual Cell
ESS.
Configure Virtual Cell Overflow with the CLI
In the CLI, a new command, overflowfrom-essprofile, has been added for this
purpose. See the example below.
default(0)# show essid
ESS Profile Name SSID Security Profile
Broadcast Tunnel Interface Type
vcelloverflow vcelloverflow default
on none
ESS Profile(1 entry)
default(0)# configure terminal
default(0)(config)# essid vcelloverflowoss
default(0)(config-essid)# overflowfrom- essprofile vcelloverflow
default(0)(config-essid)# end
