Enhancing Resilience for High Availability IP-based Signaling Transport

Abstract:
With network operators migrating from circuitswitched networks to IP networks, the need for a concept to provide operator grade trunk signaling over IP arises. A solution to enable signaling transport over IP is defined by the IETF SIGTRAN framework that allows for interworking with the Signaling System No. 7 (SS7). SIGTRAN is based on the Stream Control Transmission Protocol (SCTP) that also has a built-in redundancy mechanism, which allows switching to an alternative destination address (failover). Existing work showed that a failover performance comparable to SS7 can be achieved by aggressively setting the SCTP protocol parameters. However, this brings about possible stability issues because these parameter settings seriously impair the protocol mechanisms responsible for reacting to delay variations and congestion situations. We propose a set of network redundancy mechanisms that resolve most network failures transparently to SCTP. In order to eliminate possible stability issues, we use the default SCTP protocol parameters. Simulation results confirm that the proposed architecture can noticeably improve the robustness to concurrent network failures and achieve a similar delay behavior without jeopardizing the protocol stability.