Traffic Management for Next Generation Transport Networks

Video services are believed to be prevalent in the next generation transport networks. The popularity of these bandwidth-intensive services, such as Internet Protocol Television (IPTV), online gaming, and Videoon- Demand (VoD), are currently driving the network service providers to upgrade their network capacities.

However, in order to provide more advanced video services than simply porting the traditional television services to the network, the service provider needs to do more than just augment the network capacity. Advanced traffic management capability is one of the relevant abilities required by the next generation transport network to provide Quality-of-Service (QoS) guaranteed video services.

Augmenting network capacity and upgrading network nodes indicate long deployment period, replacement of equipment and thus significant cost to the network service providers. This challenge may slacken the steps of some network operators towards providing IPTV services. In this dissertation, the topology-based hierarchical scheduling scheme is proposed to tackle the problem addressed.

The scheme simplifies the deployment process by placing an intelligent switch with centralized traffic management functions at the edge of the network, scheduling traffic on behalf of the other nodes. The topology-based hierarchical scheduling scheme is able to provide outstanding flow isolation due to its centralized scheduling ability, which is essential for providing IPTV services.

In order to reduce the required bandwidth, multicast is favored for providing IPTV services. Currently, transport networks lack sufficient multicast abilities. With the increase of the network capacity, it is challenging to build a multicast-enabled switch for the transport network, because, from the traffic management’s perspective, the multicast scheduling algorithm and the switch architecture should be able to scale in switch size and link speed.

The Multi-Level Round-Robin Multicast Scheduling (MLRRMS) algorithm is proposed for the Input Queuing (IQ) multicast architecture in this dissertation. The algorithm is demonstrated a low implementation and computing complexity, and high performances in terms of delay and throughput. This contribution makes it possible to provide QoS control in a very high-speed switch, such as 100 Gbit/s Ethernet switch.

In addition to the multicast scheduling algorithm, the switch fabric, which is the core of the switching system, should also be able to scale and deliver excellent QoS performances. One challenge is to solve the Out-Of-Sequence (OOS) problem of the multicast cells in the three-stage Clos-network, a type of multistage switch fabrics with a larger scalability than single-stage switch fabrics.

In this dissertation, two cell dispatching schemes are proposed for the Space-Memory-Memory (SMM) Clos architecture, which are the Multicast Flow-based DSRR (MF-DSRR) and the Multicast Flow-based Round-Robin (MFRR). Both schemes are capable of reducing the OOS problem, and thus decrease the reassembly delay and buffer size.

This improvement is of great significance for the multicast switching service, which is foreseen to be extensively used in the next generation transport network. To sum up, this dissertation discusses the traffic management for the next generation transport network, and proposes novel scheduling algorithms to solve some of the challenges currently encountered by both the academia and the industry.

The covered topics in this dissertation are related to the two projects: High quality IP network for IPTV and VoIP (HIPT) and The Road to 100 Gigabit Ethernet (100GE), which are detailed in the dissertation.