Meru Technical Note - How does the keep-alive between the AP and controller work, and what is the port on which the keep-alives are sent?

[nsamuel]

Description

How does the keep-alive between the AP and controller work, and what is the port on which the keep-alives are sent?

Scope

KB Article Type - Design

Related Products - All controller and AP models

Related Software Versions - All S/W versions

Keywords - Keep-alive

Solution

Keep-alives are sent from the controller to all Enabled/Online APs. Here are some key points to know about the keep-alive function:

Keep-alive "request" packets are sent by the controller to each Enabled/Online AP.

The keep-alive "response" is sent from the AP -> controller.

Keep-alives are sent to every AP once per second. This one-second time window also serves as the timeout. That is, if a keep-alive response is sent back by an AP to the controller, but it is received > 1 second after the keep-alive request was sent, that constitutes a "missed" keep-alive.

Keep-alive requests and responses are sent using "COMM", which is a UDP port 5000 packet when using L3 and an Ethernet type 0x4001 when using L2.