Asterisk Performance Testing
Over the last couple of months we have been stress testing Asterisk V1.4 to understand its performance. We started using V1.4.4 and advanced to V1.4.11 as new releases were made available. We have been stress testing Asterisk configured as a SIP Back to Back User Agent (B2BUA) installed on a server with two, dual core, Xeon 5140 CPUs running at 2.33 GHz.
The performance results look very good. When there is no transcoding, Asterisk can handle approximately 1500 simultaneous calls. When using a $3000 server to host Asterisk, this works out to be $2 per port which is a very low investment. When calls are transcoded from the G.711 codec to G.729, the maximum number of simultaneous calls is approximately 400. The economics are quite different when transcoding is required since there is a $10 per port patent royalty for using the G.711 to G.729 transcoding algorithm. The per port cost for using Asterisk with G.711 to G.729 transcoding is $17.50 per port. (Note, the $10 per port patent royalty is the amount charged if you purchase a transcoding license from Digium. OEM vendors could negotiate a lower royalty fee directly from the patent holders, but this is not practical for end users.)
More importantly, we have seen a big improvement is stability between V1.4.4 and V1.4.11. We have found that V1.4.11 has been very stable in prolonged, high volume stress tests. We expect that V1.4.11 will be the foundation of Asterisk Business Edition Rev C which should be released later this year. We see Asterisk Business Edition Rev C to be a quantum leap forward compared to earlier versions of Asterisk Business Edition.
We will publish all the details of our test plan, a summary of the test results and all the raw data on the TransNexus web site (TransNexus.com) in the coming weeks.
If you have any comments or experience sizing server hardware for Asterisk in carrier operations please post your information here.