[Devel] rand function in config file

[Hendrik Scholz]

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Hi Klaus!

Klaus Darilion wrote:
> I once thought of having a mechanism which checks the input queue of the
> sockets. If it reaches a certain level, some messages get rejected, e.g.:
...
> reject REGISTER

Sampling messages during a timeframe and blocking messages after a
certain threshold was exceeded could be a very bad idea.
Rejected devices will retransmit or retry registering after a fixed
time. If your clients are either all the same or all use the same timer
you'll end up with yet another load peak after the retry timer fires.

For the SER ratelimit module we have RED (random early detection).
In a nutshell it samples the number of messages and for the next
timeframe drops every n-th message in order to get the total number
allowed through below the threshold.

We are also looking into hacking ratelimit up or rewriting it
to fit more needs.
We also looked into writing a 'random' function to be able to
write custom Retry-After headers and even out the load peaks.

There is an ongoing 'ratelimit revamp' thread on serdev@

Just my $.02,
 Hendrik

- --
Hendrik Scholz - <hscholz at raisdorf.net> - http://www.wormulon.net/
drag me, drop me - treat me like an object
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