You may already be familiar with Kamailio’s Disptacher module, if you’re not, you can learn all about it in my Kamailio Bytes – Dispatcher Module post.
One question that’s not as obvious as it perhaps should be is the different states shown with kamcmd dispatcher.list command;
So what do the flags for state mean?
The first letter in the flag means is the current state, Active (A), Inactive (I) or Disabled (D).
The second letter in the flag means monitor status, Probing (P) meaning actively checked with SIP Options pings, or Not Set (X) denoting the device isn’t actively checked with SIP Options pings.
AP – Actively Probing – SIP OPTIONS are getting a response, routing to this destination is possible, and it’s “Up” for all intents and purposes.
IP – Inactively Probing – Destination is not meeting the threshold of SIP OPTIONS request responses it needs to be considered active. The destination is either down or not responding to all SIP OPTIONS pings. Often this is due to needing X number of positive responses before considering the destination as “Up”.
DX – Disabled & Not Probing – This device is disabled, no SIP OPTIONS are sent.
AX – Active & Not Probing– No SIP OPTIONS are sent to check state, but is is effectively “Up” even though the remote end may not be reachable.