Network accounting, forensics, security, and performance monitoring applications often need to examine detailed traces from subsets of flows ("subpopulations"), where the application desires flexibility in specifying the subpopulation (e.g., to detect a portscan, the application must observe many packets between a source and a destination with one packet to each port). However, the dynamism and volume of network traffic on many high-speed links necessitates traffic sampling, which adversely affects subpopulation monitoring: because many subpopulations of interest to operators are low-volume flows, conventional sampling schemes (e.g., uniform random sampling) miss much of the subpopulation's traffic. Today's routers and network devices provide scant support for monitoring specific traffic subpopulations.

Overlay routing operating in a selfish manner is known to cause undesired instability when it interacts with native layer routing. We observe similar selfish behavior with the BitTorrent protocol, where its performance-awareness causes it to constantly alter the routing decisions (peer and piece selection). This causes fluctuations in the load experienced by the underlying native network. By using real BitTorrent traces and a comprehensive simulation with different network characteristics, we show that BitTorrent systems easily disrupt the load balance across inter-domain links. Further, we find that existing native layer traffic management schemes suffer from several downsides and are not conducive to deployment. To resolve this dilemma, we propose two BitTorrent strategies that are effective in resolving the cross-layer conflict.

The traffic exchanged between two overlay nodes in different autonomous systems (AS) is always subjected to a series of inter-domain policies. However, overlay routing often manages to get around these policy restrictions by relaying traffic through multiple legitimate segments, in order to achieve its selfish goals (e.g., better latency paths between end- systems). We focus on the violation of a generalized exit policy, which specifies the exact next hop AS and the egress inter- domain link for a destination address prefix. We characterize the different types of these exit policy violations and investigate their extent in a Planetlab testbed. It is conceivable that the native ASes will eventually realize the negative impact of the exit violations and adopt stringent strategies to enforce the exit policies, thereby causing deterioration in overlay performance. In this context, based on our findings from a previous study[l], we develop a pricing-based strategy that an overlay service provider can use to obtain permits from a near-optimal set of native ASes, in an effort to regain its routing advantage within a fixed budget. Further, we illustrate the use of this approach on our case study overlay network.

Overlay routing is known to cause undesired instability in a network by operating in a selfish manner. The objectives of overlay routing, such as optimizing end-to-end latency, are often in conflict with the objectives of traffic engineering in the native layer, which is concerned about balancing load. In our work, we build on past research that has investigated the recurring non-cooperative interaction between overlay routing and traffic engineering, and develop strategies that improve the routing performance of a particular layer with incomplete information about the other layer. In our strategies, one layer acts as a leader that predicts the follower's reaction and undertakes countermeasures to prevent future deterioration in performance. Specifically, we propose two classes of strategies - friendly or hostile - for each layer. By simulating under different network characteristics, we show that these preemptive strategies achieve near-optimal performance for the leader and increase the overall stability of the network. Furthermore, we observe that the best performance for a particular layer is achieved only when the goals of the other layer are completely violated, thereby motivating a higher level of selfishness.

The Internet is a complex structure arising from the interconnection of numerous autonomous systems (AS), each exercising its own administrative policies to reflect the commercial agreements behind the interconnection. However, routing in service overlay networks is quite capable of violating these policies to its advantage. To prevent these violations, we see an impending drive in the current Internet to detect and filter overlay traffic. In this paper, we first present results from a case study overlay network, constructed on top of Planetlab, that helps us gain insights into the frequency and characteristics of the different inter-domain policy violations. We further investigate the impact of two types of overlay traffic filtering that aim to prevent these routing policy violations: blind filtering and policy- aware filtering. We show that such filtering can be detrimental to the performance of overlay routing. We next consider two approaches that allow the overlay network to realize the full advantage of overlay routing in this context. In the first approach, overlay nodes are added so that good overlay paths do not represent inter-domain policy violations. In the second approach, the overlay acquires transit permits from certain ASes that allow certain policy violations to occur. We develop a single cost-sharing framework that allows the incorporation of both approaches into a single strategy. We formulate and solve an optimization problem that aims to determine how the overlay network should allocate a given budget between paying for additional overlay nodes and paying for transit permits to ASes. We illustrate the use of this approach on our case study overlay network and evaluate its performance under varying network characteristics.

Abstract — Overlay networks have recently gained attention as a viable alternative to overcome functionality limitations of the Internet. We are concerned with scenarios where a dynamic routing protocol is employed in the overlay network to adapt overlay routing tables to changing network conditions. At the same time, the native network over which the overlay is built also runs its own set of dynamic routing protocols. We are interested in investigating the behavior of this mixed routing environment and in particular the characteristics of the interaction between these two routing layers. In this paper, we focus on the specific problem of rerouting around failed links. We first study a Dual Rerouting scenario in which the two routing layers run completely independent of each other. Our goal is to understand the effect of the various settings of routing protocol parameters on the packet loss, number of route flaps, and the optimality of the adopted overlay path. We show that Dual Rerouting provides relatively fast path recovery. But, it tends to be sub-optimal in terms of the number of route flaps and the overlay path cost inflation. This is due to the overlap of functionality between the two layers, unawareness of the other layer’s decisions, and lack of flexibility. We next investigate schemes that increase awareness of the native routing protocol and its parameters at the overlay layer. We consider three such approaches: Probabilistically Suppressed Overlay Rerouting, Deferred Overlay Rerouting and Follow-on Suppressed Overlay

IP over optical is being envisioned as one of the most attractive architectures for the new Internet. There have been various proposals in IETF and other international standards organizations regarding the interaction of IP routers and optical core networks. This paper describes the architectural alternatives for the integration of IP and DWDM networks using Multiprotocol Lambda Switching (MPLambdaS). The paper also addresses the issues of routing, signaling, control and survivability in an all-optical network.

Challenges presented by the exponential growth of the Internet have resulted in the intense demand for broadband services. Providing bandwidth and connectivity on demand has risen to be an important goal for service providers. To realize this, signaling in the optical network seems to be a critical component. Provisioning involves establishing a circuit from one client end system to another, through the optical backbone. With this general notion, this paper discusses in brief the role of signaling in all-optical networks, which employ DWDM for lower layer transport. The architectural choices pertaining to lightpath services are outlined. Signaling procedures for ensuring dynamic end-to-end lightpath setup have also been presented. Path provisioning comprises a string of operations like service and neighbor discovery, route computation, signaling requests, and path setup. This paper tries to summarize the various strategies, designed for each step, for use in the all-optical networks.