  VoIP is becoming a low-priced and efficient replacement for PSTN in
communication industries. With a widely growing adoption rate, SIP is an
application layer signaling protocol, standardized by the IETF, for creating,
modifying, and terminating VoIP sessions. Generally speaking, SIP routes a call
request to its destination by using SIP proxies. With the increasing use of
SIP, traditional configurations pose certain drawbacks, such as ineffective
routing, un-optimized management of proxy resources (including CPU and memory),
and overload conditions. This paper presents OpenSIP to upgrade the SIP network
framework with emerging technologies, such as SDN and NFV. SDN provides for
management that decouples the data and control planes along with a
software-based centralized control that results in effective routing and
resource management. Moreover, NFV assists SDN by virtualizing various network
devices and functions. However, current SDN elements limit the inspected fields
to layer 2-4 headers, whereas SIP routing information resides in the layer-7
header. A benefit of OpenSIP is that it enforces policies on SIP networking
that are agnostic to higher layers with the aid of a Deep Packet Inspection
(DPI) engine. Among the benefits of OpenSIP is programmability, cost reduction,
unified management, routing, as well as efficient load balancing. The present
study implements OpenSIP on a real testbed which includes Open vSwitch and the
Floodlight controller. The results show that the proposed architecture has a
low overhead and satisfactory performance and, in addition, can take advantage
of a flexible scale-out design during application deployment.
