Creating robust, scalable, highly available components to provide feature rich VoIP capabilities
A growing class of applications, including VoIP, IM and Presence are
enabled by the Session Initiation Protocol (SIP). To support the rich
functionality required by these applications, resource consumption at a
SIP server varies widely based on request type, state maintained and
routing actions. In addition each call setup utilizes network resources
and is affected by latency, bandwidth and other QoS parameters. We are
trying to determine the cost contributions of each of these blocks on
the performance of SIP components to create a scalable and highly
available topography of SIP servers.
The first part of our work has experimentally evaluated the resource
consumption of functionality blocks such as parsing, state maintenance
and memory processing within a representative SIP server, OpenSER, for
different use case scenarios and thus proposed key insights into
mechanisms to increase SIP server scalability.
The second part of our work has focused on studying the impact that
authentication services have on the performance and scalability of SIP proxies.
In particular, we are interested in distributed SIP infrastructures where
database and network latencies are the main factors affecting performance. Our
goal is to make SIP authentication more efficient and secure without requiring
additional resources. In this way, more messages and applications will be able
to use authentication, eliminating known vulnerabilities.
Using a modified version of OpenSER in a distribute topology, we demonstrated
that the traditional approach of simply launching a large number of parallel
processes to reduce the impact of network latency not only incurs in
substantial overhead and increases dropped calls, but can actually decrease call
throughput. Using our proposed technique, batch requests, in combination with
parallel processes, we significantly reduce the cost and increase the
throughput of authentication for large-scale networks supporting SIP
applications.
Current work is evaluating a new SIP authentication algorithm that promises
better performance, scalability and security than Digest authentication. The
new algorithm is based on the concept of hash chains and temporary
authentication vectors to reduce the number of requests to the database. The
new algorithm also allows mutual authentication, a well-known limitation of
Digest authentication.
Vijay A. Balasubramaniyan, Arup Acharya, Mustaque Ahamad, Mudhakar Srivatsa, Italo Dacosta and Charles P. Wright. SERvartuka: Dynamic Distribution of State to Improve SIP Server Scalability. Accepted at the 28th International Conference on Distributed Computing Systems (ICDCS 2008), Beijing, China, June 2008. pdf
Italo Dacosta, Vijay Balasubramaniyan, Mustaque Ahamad and Patrick Traynor, Improving Authentication Performance of Distributed SIP Proxies, Conference on Principles, Systems and Applications of IP Telecommunications (IPTComm), Atlanta, USA, July 2009.pdf
Vijay A. Balasubramaniyan, Arup Acharya, Mustaque Ahamad, and Charles P. Wright. A method and apparatus for autonomically regulating ratio of stateful to stateless transaction processing for increasing scalability in a network of SIP servers. Filed in April 2007.