Hello,
On 10/27/11 5:30 PM, Asgaroth wrote:
Hi Daniel,
[...]
Since with 3.2 seemed that it was lost capability to go inactive after
a certain number of failures (ds_probing_threshold), there is a new
state 'trying' that can be used for it. Means that you can set a
destination in trying state couple of times and then it becomes
inactive. In 3.1 it was using a confusing mechanism based on probing mode.
Can you explain this trying state and "lost capability to go inactive
after certain number of failures" a little more please and how it
relates to the new trying->inactive states. I would like to understand
how these states relate so that I can test better.
I was not using the feature in the past, but from the source code I
could see that there was a way not to go directly in probing mode (which
in the past meant not to select the gateway anymore), but just count
failure until a threshold is reached and then set probing.
So if threshold was 3 and there were (in 3.1.x-):
ds_mark_dst(p) => state still active (no probing, gateway still selected)
ds_mark_dst(p) => state still active (no probing, gateway still selected)
ds_mark_dst(p) => state goes to probing (inactive, gateway not selected)
Now (3.3.x+), since probing can be always on, even for active
destinations (to detect when they go down), you can get previous like
behavior with trying state:
ds_mark_dst(t) => state trying (gateway still selected)
ds_mark_dst(t) => state trying (gateway still selected)
ds_mark_dst(t) => state goes to inactive (gateway not selected)
Default failure counter threshold is 1, so goes to inactive as soon as
you set trying, but you can change it via ds_probing_threshold parameter.
So right now there are states: active, inactive, trying and disabled,
plus modes: probing, not-probing. A destination can be selected only
if it is active or trying. It will not be selected in inactive and
disabled. Probing mode specifies whether keepalives should be sent to
destinations, can be done per address or globally with the module
parameter ds_probing_mode. If a keepalive is not replied, the address
is marked as trying first and later will become inactive if keeps
being non-responsive.
OK, so if I understand this above paragraph correctly, if I have
ds_probing_mode = 0, then I need to set mode manually to probing for a
gateway that has failed "ds_probing_threshold" times? If a server times
out and I set state/mode to "ip", then I assume probing will commence.
In this case the server will not responde to probe requests (as it has
crashed), does this mean then that the state will change to "trying"
because there was no probe response recieved from destination?
Probing is no longer a gw selection state, but a mode switch to send
keepalives or not to a gateway. So if you want these keepalives and
ds_probing_mode=0, you have to set 'p' in any of the states you want
keepalives. A matter of the reply code from keepalives, the state in
probing mode is changed to active if it is 200ok or a reply code
configured in module parameter, or to trying if it is a failure (which
may end up in inactive when failure threshold is met). ds_probing_mode
controls as well if a keepalive reply will maintain the probing mode or not.
Cheers,
Daniel
--
Daniel-Constantin Mierla -- http://www.asipto.com
Kamailio Advanced Training, Dec 5-8, Berlin: http://asipto.com/u/kat
http://linkedin.com/in/miconda -- http://twitter.com/miconda
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