Resilience and Quality of Service Assurance Methods in Ethernet and UTRAN Networks
János Farkas · 2011
The use of packet switched technologies such as Ethernet or IP in telecommunications networks requires the application of quality assurance solutions in order to meet the telecom grade requirements. Ethernet is attractive to network providers due to the high bandwidth provided at low cost, therefore, Ethernet is evolving from the enterprise to the carrier. Nevertheless, as a LAN technology, Ethernet did not offer the features that are very important in the new carrier grade application areas, e.g. fast failure handling and sophisticated management. One of the most important carrier grade requirements is resilience as it is the basis to provide Quality of Service (QoS) guarantees to the customers. Carriers have got used to the failover performance and robustness of the SONET/SDH networks, hence they expect similar performance from a packet network too. However, the control protocols of Ethernet networks did not provide a controllable bounded failover time or they were not applicable in arbitrary network topologies. Therefore, I proposed a scalable resilient architecture in order to meet the carrier grade requirements in Ethernet networks comprised of IEEE 802.1Q-2005 standard bridges. I evaluated the performance and the robustness of the architecture by means of measurements in a prototype implementation. A recent development in Ethernet networks is the introduction of link state control as specified by the IEEE 802.1aq Shortest Path Bridging (SPB) standard, which aims to improve resilience among its goals. However, the introduction of link state control in Ethernet networks raises some issues among which loop prevention is the most crucial one. Therefore, I proposed loop prevention solutions that can be implemented as extensions to a standard link state protocol, e.g. IS-IS. I proved that the proposed algorithms prevent the occurrence of loops; furthermore, I evaluated their performance by means of simulations. Internet Protocol is also widely used for transport. Radio Access Networks, e.g. UTRAN networks are often based on IP. Nevertheless, to meet the stringent QoS requirements of the real time traffic, specific solutions are needed, e.g. Connection Admission Control (CAC). I proposed analytical CAC algorithms that take into account the characteristics of UTRAN and allow the utilisation of network resources; furthermore, I evaluated the CAC algorithms by means of simulations.