Kin-n Ho

An overview of routing optimization for internet traffic engineering

Traffic engineering is an important mechanism for Internet network providers seeking to optimize network performance and traffic delivery. Routing optimization plays a key role in traffic engineering, finding efficient routes so as to achieve the desired network performance. In this survey we review Internet traffic engineering from the perspective of routing optimization. A taxonomy of routing algorithms in the literature is provided, dating from the advent of the TE concept in the late 1990s. We classify the algorithms into multiple dimensions: unicast/multicast, intra-/inter- domain, IP-/MPLS-based and offline/online TE schemes. In addition, we investigate some important traffic engineering issues, including robustness, TE interactions, and interoperability with overlay selfish routing. In addition to a review of existing solutions, we also point out some challenges in TE operation and important issues that are worthy of investigation in future research activities.

Heterogeneous real-time traffic admission control in differentiated services domains

In differentiated services (DiffServ) domains, where services are provisioned on a per-class basis, admission control is an essential control factor in order to ensure that congestion is avoided and that the quality of service (QoS) requirements of individual flows are met. We consider traffic-engineered and provisioned IP differentiated services domains able to support real-time traffic. We present a new measurement-based admission control (MBAC) scheme that uses measurements of aggregate bandwidth only, without keeping the state of any per-flow information. In our scheme there is no assumption made on the nature of the traffic characteristics of the real-time sources, which can be of any heterogeneous nature. Through simulations we show that the admission control scheme is robust with respect to traffic heterogeneity and measurement errors. We also show that our approach compares favorably against other admission control schemes found in the literature.

Adaptive multi-topology IGP based traffic engineering with near-optimal network performance

In this paper we present an intelligent multi-topology IGP (MT-IGP) based intra-domain traffic engineering (TE) scheme that is able to handle unexpected traffic fluctuations with near-optimal network performance. First of all, the network is dimensioned through offline link weight optimization using Multi-Topology IGPs for achieving maximum path diversity across multiple routing topologies. Based on this optimized MT-IGP configuration, an adaptive traffic engineering algorithm performs dynamic traffic splitting adjustment for balancing the load across multiple routing topologies in reaction to the monitored traffic dynamics. Such an approach is able to efficiently minimize the occurrence of network congestion without the necessity of frequently changing IGP link weights that may cause transient forwarding loops and routing instability. Our experiments based on real network topologies and traffic matrices show that our approach has a high chance of achieving near-optimal network performance with only a small number of routing topologies.

On egress router selection for inter-domain traffic with bandwidth guarantees

As the Internet has grown in size and diversity of applications, the next generation is designed to accommodate flows that span over multiple domains with quality of service guarantees, and in particular bandwidth. In that context, a problem emerges when destinations for inter-domain traffic may be reachable through multiple egress routers. Selecting different egress routers for traffic flows can have diverse effects on network resource utilization. In this paper, we address a critical provisioning issue of how to select an egress router that satisfies the customer end-to-end bandwidth requirement while minimizing the total bandwidth consumption in the network.

Improving survivability through traffic engineering in MPLS networks

The volume of higher priority Internet applications is increasing as the Internet continues to evolve. Customers require quality of service (QoS) guarantees with not only guaranteed bandwidth and delay but also with high availability. Our objective is for each estimated traffic flow to find a primary path with improved availability and minimum failure impact while satisfying bandwidth constraints and also minimizing network resource consumption. We devise a heuristic algorithm with four different cost functions to achieve our objective. Our approach can enhance availability of primary paths, reduce the effect of failure and also reduce the total resource consumption for both primary and backup paths.

Multi-objective Egress Router Selection Policies for Inter-domain Traffic with Bandwidth Guarantees

The next generation Internet is designed to accommodate flows that span across multiple domains with quality of service guarantees, in particular bandwidth. In this context, destinations for inter-domain traffic may be reachable through multiple egress routers within a domain. In this paper, we formulate a bandwidth guaranteed egress router selection problem. The objective is to, for each aggregated inter-domain traffic flow, select an egress router that satisfies the end-to-end bandwidth requirement while optimizing the network resource utilization by which we consider three objective functions: minimizing the total bandwidth consumption, improving intra-domain and inter-domain load balancing in the network. We propose a heuristic algorithm with five egress router selection policies to solve this problem. The evaluation of these egress router selection policies through simulation benefits ISPs by choosing the one that fits their target objectives.

Inter-autonomous system provisioning for end-to-end bandwidth guarantees

This paper addresses the issue of provisioning end-to-end bandwidth guarantees across multiple Autonomous Systems (ASes). We first review a cascaded model for negotiating and establishing service level agreements for end-to-end bandwidth guarantees between ASes. We then present a network dimensioning system that uses traffic engineering mechanisms for the provisioning of end-to-end bandwidth guarantees. The network dimensioning system solves two problems: (1) the economic problem of how to determine the optimum amount of bandwidth that needs to be purchased from adjacent downstream ASes at a minimum total cost; (2) given the available bandwidth resources within and beyond the AS as a result of (1), the engineering problem of how to assign bandwidth guaranteed routes to the predicted traffic while optimizing the network resource utilization. We formulate both as integer-programming problems and prove them to be NP-hard. An efficient genetic algorithm and an efficient greedy-penalty heuristic are, respectively, used to solve the two problems and we show that these perform significantly better than simple heuristic and random approaches.

Green MPLS Traffic Engineering

Conserving energy consumption in the Internet has attracted much attention in recent years. During the non-peak time in daily network operations, it is possible to put a subset of routers to sleep mode for energy conservation purposes without network performance deterioration. This paper proposes a practical green traffic engineering scheme called Greedy Green MPLS Traffic Engineering Scheme (GGMTES) to save energy in multi-protocol label switching (MPLS) networks. During the non-peak time, GGMTES arranges some routers into sleep mode to save energy and re-routes all traffic for load balancing with minimum re-configuration overhead. Our simulation results show that GGMTS can save up to 15% more energy than an existing approach without network performance deterioration.

Fast Network Failure Recovery Using Multiple BGP Routing Planes

We present an efficient multi-plane based fast network failure recovery scheme which can be realized using the recently proposed multi-path enabled BGP platforms. We mainly focus on the recovery scheme that takes into account BGP routing disruption avoidance at network boundaries, which can be caused by intra-AS failures due to the hot potato routing effect. On top of this scheme, an intelligent IP crank-back operation is also introduced for further enhancement of network protection capability against failures. Our simulations based on both real operational network topologies and synthetically generated ones suggest that, through our proposed optimized backup egress point selection algorithm, as few as two routing planes are able to achieve high degree of path diversity for fast recovery in any single link failure scenario.

Peer-to-Peer Batching Policy for Video-on-Demand System

In this paper, an enhanced peer-to-peer batching policy (EPPB) is developed for providing true video-on-demand (VoD) services in multicast environment. It is accomplished by exploring the multicast delivery coupled with peer-to-peer (P2P) transmission strategy for video streaming such that gets benefit from both transmission schemes to efficiently deliver video data to the clients. The results show that this enhanced version performs better than the original version in terms of total bandwidth requirement up to 30%