Protecting the multimedia core network from traffic congestion and denial of service (DOS) attacks is a great challenge for service providers. Indeed, peaks of traffic can be received either from the users or from interconnections and produce congestions in the core network, hampering the service for end users.
Bilateral agreements related to interconnection between operators mention the maximum number of sessions, and traffic rate in term of call attempts per second (CAPS). In case of excess traffic, an operator can block it to protect its own core network.
Capping the number of received SIP requests per second blocks either malicious users attempting to overload the network or regulates users’ registration storms following an access network failure.
However, blocking random messages also leads to disturb calls previously established and accepted. Indeed, a call involves at least seven SIP requests and answers, and it is important to accept all of them for the call to succeed.
In the SBC software release 6.2, Cirpack has added a new mechanism to limit the incoming and outgoing call attempts per second while preserving the calls previously accepted. When an interconnection threshold is reached, only new calls are rejected to protect the core network.
This feature helps the service provider to protect its network from congestion and to implement the interconnection agreements, while ensuring the best quality of experience for end users.
* Available in SBC release 6.2