Soip Over Satellite Testing - TIM Experience

In the present Mobile Telecommunications scenario, the transmission of SS7 signalling on traditional TDM circuits is evolving to a SS7 over IP network (SoIP) solution, due to the continuous efficiency research in optimizing transmission and to the continuous goal of cost reduction. Some operators are using SoIP network in a national environment, while international SoIP networks are going to be deployed in a few years. Since transmissions over satellite may represent a fast way to deploy an international Backbone, TIM performed a trial in cooperation with TILAB, using Cisco Signalling Gateways and EUTELSAT satellite network. This paper describes the most significant results obtained by this experience, with respect to two critical aspects of satellite connection: the Transmission Delay and the Bandwidth Availability. Satellite delay put in evidence some practical limitations for the current Cisco release (called MB9), if compared with the traditional terrestrial Backbone; a special up-graded release (MB9-SAT) resolved them, but dynamic allocation of bandwidth asked for a detailed investigation on configuration criteria, in order to avoid system congestion. Both releases have been tested also with a delay-line simulator, to examine their performances on traffic management with delay varying between 0 and 700 ms. These activities drove us to outline an operative reference model, useful to understand network behavior under different conditions and to configure its fundamental parameters. Glossary BETH: Signalling on Ethernet traffic Band BIN: Traffic Band injected into IP Network BIN, max: Maximum threshold of BIN before congestion BS: Total Satellite Band BSS7: Signalling traffic Band ∆B: Increase of Signalling traffic band CWND: Congestion Window DAMA: Dynamic Assignment Multiple Access DPC: Destination Point Code EUTELSAT: Satellite Communications company GTT: Global Title Translation IETF: Internet Engineering Task Force IP: Internet Protocol M2PA: MTP2 user Peer-to-peer Adaptation layer MSU : Message Signalling Unit MTP2: Message Transfer Part 2 MTP3: Message Transfer Part 3 NA: SCTP Associations’ Number OSI: Open System Interconnection PAMA: Permanent Assignment Multiple Access RTT: Round Trip Time SIGTRAN : Signalling Transport SCCP: Signlling Connection Control Part SCTP: Stream Control Transmission Protocol SG: Signaling Gateway SoIP : Signalling SS7 over Internet Protocol SS7: Signalling System n.7 TACK / TALL: ACKnowledge / ALLocation Time TCP: Transport Control Protocol TDM: Time Division Multiplexing TDMA: Time Division Multiple Access TILAB: Telecom Italia LABoratories TIM: Telecom Italia Mobile S.p.A. TT: Traffic Terminal VLAN: Virtual Local Area Network WAN: Wide Area Network