Page 45 - Asterisk™: The Future of Telephony

The obvious conclusion is that you should get the most powerful CPU your budget will
allow. However, don’t be too quick to buy the most expensive CPU out there. You’ll
need to keep the requirements of your system in mind; after all, a Formula 1 Ferrari is
ill-suited to the rigors of rush-hour traffic. Slower CPUs will often run cooler and, thus,
you might be able to build a lower-powered, fanless Asterisk system for a small office,
which could work well in a dusty environment, perhaps.

In order to attempt to provide a frame of reference from which we can contemplate our
platform decision, we have chosen to define three sizes of Asterisk systems: small,
medium, and large.

Small systems
Small systems (up to 10 phones) are not immune to the performance requirements of
Asterisk, but the typical load that will be placed on a smaller system will generally fall
within the capabilities of a modern processor.
If you are building a small system from older components you have lying around, be
aware that the resulting system cannot be expected to perform at the same level as a
more powerful machine, and will run into performance degradation under a much
lighter load. Hobby systems can be run successfully on very low-powered hardware,
although this is by no means recommended for anyone who is not a whiz at Linux
performance tuning. §
If you are setting up an Asterisk system for the purposes of learning, you will be able
to build a fully featured platform using a relatively low-powered CPU. The authors of
this book run several Asterisk lab systems with 433 MHz to 700 MHz Celeron pro-
cessors, but the workload of these systems is minimal (never more than two concurrent
calls).

AstLinux and Asterisk on OpenWRT
If you are really comfortable working with Linux on embedded platforms, you will want
to join the AstLinux mailing list and run Kristian Kielhofner’s creation, AstLinux, or
get yourself a Linksys WRT54GL and install Brian Capouch’s version of Asterisk for
that platform.
These projects strip Asterisk down to its essentials, and allow incredibly powerful PBX
applications to be deployed on very inexpensive hardware.

‡ If you want to be completely up to the minute on which CPUs are leading the performance race, surf on over
to Tom’s Hardware (http://www.tomshardware.com) or AnandTech (http://www.anandtech.com), where you
will find a wealth of information about both current and out-of-date CPUs, motherboards, and chipsets.
§ Greg Boehnlein once compiled and ran Asterisk on a 133 MHz Pentium system, but that was mostly as an
experiment. Performance problems are far more likely, and properly configuring such a system requires an
expert knowledge of Linux. We do not recommend running Asterisk on anything less than a 500 MHz system
(for a production system, 2 GHz might be a sensible minimum). Still, we think the fact that Asterisk is so
flexible is remarkable.

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