Scalable and energy-efficient packet switches based on multi-granular forwarding operations

Abstract

Telecommunication networks are evolving due to rapid growth of internet traffic and the necessity to satisfy the new requirements of emerging packet services. Upgrading of network devices so as they can allow scalable and full line rate traffic aggregation and eliminate any internal performance bottlenecks is crucial. In packet switching devices, since data plane functionalities need to be executed for each incoming packet and power per given bandwidth is strongly related to the amount of processing on this data, packet processing at ultra-high rate is becoming the major challenge. The main trend to address such power consumption and scalability issues is to bypass packet switches by switching traffic at lower layers. This results in the packet optical transport network approach, where packet switching provides flexible end-to-end connectivity based on tunnel encapsulation while wavelength switching, exploiting optical bypass, allows reducing electrical switch size at transit nodes. There are also opportunities consisting in simplifying packet switch functionalities or designing completely different packet switch architectures. In this paper a new Ethernet aggregation and switching solution with potentialities to simplify and scale Ethernet switch forwarding functionality is proposed. This solution, based on a burst-basis transmission compliant with the Ethernet Standard, is able to maintain flexibility and any to any connectivity deriving from the connectionless nature of Ethernet. At the same time, it provides Ethernet technology with efficient aggregation capabilities allowing to reduce processing of transit traffic. This is allowed thanks to an Ethernet burst structure conceived as a variable number of consecutive frames of the same connection preceded by a proprietary burst control frame carrying information necessary for burst data frames classification. As a result, burst control frames experience the conventional Ethernet switch packet processing while data frames are mapped on the corresponding queue/output port according to the result of control frames classification. The proposed solution also provides the possibility to recognize data frames of the same burst through a proprietary inter-frame gap inserted among them; that allows to dynamically adapt burst size to the available bandwidth at transit nodes in order to limit frame delay and jitter and to support intermediate grooming. These features make it a very competitive approach in the context of packet optical transport being able to support dynamic multi-granular switching. The proposed solution has been validated by estimating its efficiency in terms of energy consumption with respect to a commercial packet switch. The impact of burst transmission on packet delay and jitter across ring and mesh networks has been also evaluated through different sets of simulations.