[OpenSIPS-Users] Realtime monitoring of registered end-points

[Ionut Ionita]

*Hello all,

     I’m glad to announce a new feature that allows OpenSIPS to monitor
(via SIP OPTIONS probing) and disable/delete in realtime the registrations
which are not responding.
     The previous approach had two issues when came to so called “zombie”
registrations (registrations which are not valid anymore):
     * resources - such zombie registrations may waste resources in your
OpenSIPS server (memory,  processing time, DB space, useless NAT pinging,
TCP connect attempts);
     * user experience - using the zombie registration to reach un-existing
users translates into useless calls (calls that will simply timeout),
giving delays in the call setup (instead of going straight to VM, you may
burn 5-10 seconds in trying to reach the user);
     The main idea  behind these features is to delete contacts that do not
respond to a certain number of SIP pings. The SIP pinging is provided by the
nathelper module which was enhanced to keep the state of each pinging 
requests
(basically, the module is waiting and checking the reply of each SIP request
sent to the registered users). For registrations detected as “dead” (not 
responding),
the nathelper module interacts directly with the usrloc module in order to
remove the zombie contact.
     For usage perspective, the nathelper module now has two new parameters:
     * ping_threshold - timeout to consider a ping as unanswered;
     * max_pings_lost - the number of unresponded pings after which the 
contact is
removed from usrloc;
     In order to activate this feature, every contact must have the 
sipping_bflag
(to be pinged) and remove_on_timeout_bflag (to be deleted on no-answer) 
activated.
This means these flags must also be configured in the nathelper module. [0]
     For full documentation of the nathelper module including the newly 
added
feature see [1]. Any feedback is highly appreciated.

Regards,
Ionut Ionita

[0]http://www.opensips.org/html/docs/modules/2.2.x/nathelper.html#id248011
[1]http://www.opensips.org/html/docs/modules/2.2.x/nathelper.html
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