Doug Montgomery

Performance evaluation of two layered mobility management using mobile IP and session initiation protocol

In this paper we present results, which have obtained by extensive simulations for mobile IP and session initiation protocol from the perspective of VoIP service in wireless Internet access. After illustrating the problem in these two protocols for diverse cases of mobility management, we propose an integrated model, to reduce the handover latency and packet loss during handover. This combination of network and application layer mobility management model reduces disruption time during handovers and provides fast handoff for ongoing conversations. Simulation results presented in this paper are based on the ns2 mobility software. However, since the current version of ns2 does not include SIP model for VoIP service, we add a suite of new features and procedures that are specific to this paper. The simulations results show that our proposed mechanisms achieve better performance than other protocols.

Study of BGP Peering Session Attacks and Their Impacts on Routing Performance

We present a detailed study of the potential impact of border gateway protocol peering session attacks and the resulting exploitation of route flap damping (RFD) that cause network-wide routing disruptions. We consider canonical grid as well as down-sampled realistic autonomous system (AS) topologies and address the impact of various typical service provider routing policies. Our modeling focuses on three dimensions of routing performance sensitivity: 1) protocol aware attacks (e.g., tuned to RFD); 2) route selection policy; and 3) attack-region topology. Analytical results provide insights into the nature of the problem and potential impact of the attacks. Detailed packet-level simulation results complement the analytical models and provide many additional insights into specific protocol interactions and timing issues. Finally, we quantify the potential effect of the BGP graceful restart mechanism as a partial mitigation of the BGP vulnerability to peering session attacks

A Comparative Analysis of BGP Anomaly Detection and Robustness Algorithms

We present an evaluation methodology for comparison of existing and proposed new algorithms for Border Gateway Protocol (BGP) anomaly detection and robustness. A variety of algorithms and alert tools have been proposed and/or prototyped recently. They differ in the anomaly situations which they attempt to alert or mitigate, and also in the type(s) of data they use. Some are based on registry data from Regional Internet Registries (RIRs) and Internet Routing Registries (IRRs) - an example is the Nemecis tool. Others such as the Prefix Hijack Alert System (PHAS) and the Pretty Good BGP (PGBGP) are driven by BGP trace data. The trace data is obtained from Reseaux Internet Protocol Europeens - Routing Information Service (RIPE-RIS), Routeviews, or a BGP speaker where the algorithm operates. We propose a new algorithm that combines the use of both registry and trace data, and also makes some key improvements over existing algorithms. We have built an evaluation platform called TERRAIN (Testing and Evaluation of Routing Robustness in Assurable Inter-domain Networking) on which these algorithms can be tested and empirically compared based on real and/or synthetic anomalies in BGP messages. We will present a variety of results providing interesting insights into the comparative utility and performance of the various BGP robustness algorithms.

Dynamic Agent Advertisement of Mobile IP to Provide Connectivity between Ad Hoc Networks and Internet

Although the Ad Hoc On-Demand Routing Protocol (AODV) is well designed for the ad hoc network, it does not deal with Internet connectivity. While some of solutions are proposed for integrating the ad hoc networks with global Internet, there are some limitations and drawbacks. In this paper, we propose the dynamic agent advertisement to reduce the control packets overhead and the power consumption due to a redundant packet processing. We use ns2 to compare the proposed approach with the existing solutions in terms of the overhead and throughput for packet transmission.

Standardization for ubiquitous networking in IPV6-based NGN

As many new types of devices will be connected to networks in the future, we expect that IPv6 will play a key role in object-to-object communications and also militate against address exhaustion of IPv4. Therefore, it is very important to provide ubiquitous networking capabilities using IPv6. This paper presents several issues for standardization in the support ubiquitous networking capabilities in IPv6- based next generation networks (NGN). These issues are relevant to the future activities of ITU-Ts Study Group (SG) 13. We also discuss some basic concepts and present our vision related to this topic. In addition, we clearly identify the importance and key advantages of IPv6 in the ubiquitous networking environment. For developing the relevant standards to further enhance the current NGN, we propose new study items which include object identification, functional architecture, services, and strategies. We also provide additional considerations for standardization.

Mobility agent with sip registrar for VoIP services

The Session Initiation Protocol (SIP) is likely to play a key role in the convergence of Internet and the conventional cellular networks. Several issues related to mobility management in SIP enabled networks remain to be resolved. While other work has compared and contrasted mobility management in SIP and Mobile IP (MIP), in this paper we investigate possible integration techniques that combine the mobility management capabilities of both protocols. After illustrating some of the issues with each protocol when used in isolation in various mobile VoIP scenarios, we propose an integrated model (MIP+SIP), that reduces the disruption time during handovers. Our combination of network and application layer mobility management models reduces the global signaling load and provides fast handoff for ongoing conversations. Simulation results show that our proposed mechanisms achieve better performance than isolated SIP and MIP mobility management. Simulation results presented in this paper are based on the ns2 mobility package[6], which we extended with new capabilities to model SIP components (i.e., user agents, redirect servers, proxy servers, registrars) and SIP-based VoIP traffic.

Testing SIP call flows using XML protocol templates

A Session Initiation Protocol (SIP) Call Flow is a causal sequence of messages that is exchanged between interacting SIP entities. We present a novel test system for SIP based on the notion of XML Protocol Templates, of SIP call flows. These templates can be pattern matched against incoming messages and augmented with general purpose code to implement specific protocol responses. This architecture allows test systems to be easily scripted, modified and composed. We describe these techniques in the construction of a SIP web-based interoperability tester (SIP-WIT) and comment on their potential more general use for scripting SIP services.

Emergency telecommunication support for IP telephony

As universal high speed internet access becomes a reality, phone calls are increasingly being made over the Internet rather than the conventional PSTN. The danger to this trend is the un-availability of priority mechanisms for communication between emergency response personnel during times of disaster. We define a proposed architecture to enable ETS support for SIP-based VOIP systems.

Instrumenting Open vSwitch with Monitoring Capabilities: Designs and Challenges

Recent advances in Software-Defined Networking (SDN) have enabled flexible and programmable network measurement. A promising trend is to conduct network traffic measurement on widely deployed Open vSwitches (OVS) in data centers. However, little attention has been paid to the design options for conducting traffic measurement on the OVS. In this study, we set to explore different design choices and investigate the corresponding trade-offs among resource consumption, measurement accuracy, implementation complexity, and impact on switching speed. For this purpose, we empirically design and implement four different measurement schemes in OVS, by either closely integrating forwarding and measurement functions into a pipeline, or decoupling them into parallel operations. Through extensive experiments and comparisons, we quantitatively show the various trade-offs that the different schemes strike to balance, and demonstrate the feasibility of instrumenting OVS with monitoring capabilities. These results provide valuable insights into which design will best serve various measurement and monitoring needs.

vPROM: VSwitch enhanced programmable measurement in SDN

While being critical to the network management, the current state of the art in network measurement is inadequate, providing surprisingly little visibility into detailed network behaviors and often requiring high level of manual intervention to operate. Such a practice becomes increasingly ineffective as the networks grow both in size and complexity. In this paper, we propose vPROM, a vSwitch enhanced SDN programmable measurement framework that automates the measurement process, minimizes the measurement resource usage, and addresses several significant technical challenges faced by early works. vPROM leverages the SDN programmability and extends the Pyretic runtime system and OpenFlow network interface to achieve the measurement automation. The required measurement resources are minimized by only acquiring the necessary statistics, made possible with instrumented Open vSwitches1 with user defined monitoring capability. By decoupling monitoring from routing, vPROM reduces the interference between the measurement applications and other applications, and eliminates the frequent involvement of the controller. A vPROM prototype is implemented with DDoS and port-scan detection applications. The performance of vPROM is evaluated and the comparison results with other existing programmable measurement approaches are also presented.