thank you Ovidiu, the debug it really helps.
please help me out with these questions though:

modparam("ratelimit", "timer_interval", 30)

modparam("ratelimit", "pipe", "0:TAILDROP:50")

does this mean "allow up to 50 calls/sec" or "allow up to 50 calls/30sec"

or is the logic similar to:

every 30 seconds get a count of messages, if algorithm's threshold is set to 50calls/sec, then after the timer elapses (30 secs) if there are more than 50 * 30 calls/transactions during the past 30 secs then drop the next call?

with these settings should be "no more than 50 calls every second"
modparam("ratelimit", "timer_interval", 1)
modparam("ratelimit", "pipe", "0:TAILDROP:50")

I really appreciate your assitance here.
txs a lot in advance
fborot

From: fborot@hotmail.com
To: users@lists.kamailio.org
Subject: rate limit module
Date: Fri, 2 Dec 2011 14:56:28 -0500

Hello,

I am trying to use the rate limit module using Kamailio 1.5.2. I feel that I got it but I would
like some pointers and recommendations.

These are my settings: (this is a lab of course), I used 1 on the timer_interval because I am
generating the calls manually and wanted to see it in action quickly:

# ---- ratelimit -------
modparam("ratelimit", "timer_interval", 1)
modparam("ratelimit", "reply_code", 506)
modparam("ratelimit", "reply_reason", "Rejecting due to high load")
modparam("ratelimit", "queue", "0:INVITE")
modparam("ratelimit", "pipe", "0:TAILDROP:1")

then in the route section:

        if (method=="INVITE") {
                xlog("L_INFO","mylog: RL found INVITE.\n");
                if (!rl_check()) {
                        xlog("L_INFO","mylog: RL dropped message.\n");
                        rl_drop();
                        exit;
                };
                xlog("L_INFO","mylog: RL found INVITE but did not drop it.\n");
        };

The TAILDROP algorithm seems to work better than the RED, based on what I expected of course (with 1 sec timer interval and 1 calls/sec on the pipe).
Making manual calls one right after the other almost always triggered the protecting when there was another call on the same second.

But these lines (1.6.3. pipe) on the doc got me kind of confused:

" When specifying a limit, the unit depends on the algorithm used and
doesn't need to be specified also (eg, for TAILDROP or RED, limit means packets/sec, whereas with the FEEDBACK
algorithm, it means [CPU] load factor).

For these 2 lines below, does this mean that the interval =10 will be overridden by the 100 calls/sec on the TAILDROP algorithm?

modparam("ratelimit", "timer_interval", 10)
modparam("ratelimit", "pipe", "0:TAILDROP:100")

I made a quick test and with timer_interval = 10 and TAILDROP:1, it looks like the protection kicks in almost every 10 secs: (Dec 2 19:44:07 and Dec 2 19:43:57),

tail -f proxy.log | grep RL
Dec 2 19:43:53 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:43:53 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:53 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:43:53 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:53 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:43:53 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:53 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:43:53 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:54 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:43:54 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:55 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:43:55 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:56 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:43:56 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:56 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:43:56 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:56 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:43:56 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:57 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:43:57 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:57 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:43:57 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL dropped message.
Dec 2 19:43:58 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:43:58 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:59 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:43:59 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:43:59 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:43:59 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:44:01 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:44:01 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:44:02 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:44:02 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:44:02 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:44:02 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:44:04 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:44:04 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:44:06 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:44:06 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.
Dec 2 19:44:06 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:44:06 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:44:07 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE.
Dec 2 19:44:07 AW-ATL-PROXY-01 ./kamailio[17449]: mylog: RL found INVITE but did not drop it.
Dec 2 19:44:07 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:44:07 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL dropped message.
Dec 2 19:44:10 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE.
Dec 2 19:44:10 AW-ATL-PROXY-01 ./kamailio[17450]: mylog: RL found INVITE but did not drop it.