System information

To attempt to provide you with a frame of reference from which you can contemplate
your 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 performance will begin to degrade 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.
While both projects require a fair amount of knowledge and effort on your part, they
also share a huge coolness factor, are extremely popular, and are of excellent quality.
Medium systems
Medium-sized systems (from 10 to 50 phones) are where performance considerations
will be the most challenging to resolve. Generally, these systems will be deployed on
one or two servers only, and thus each machine will be required to handle more than
one specific task. As loads increase, the limits of the platform will become increasingly
§ 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 in such conditions, 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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