Thomas Heide Clausen

• cand.polyt, PhD
• Professor at École Polytechnique

In this paper, we investigate broadcasting in Mobile Adhoc NETworks (MANETs). We de ne broadcasting as being the process of delivering one packet, originated at one node, to (ideally) all other nodes in the MANET.

In this paper, we evaluate the performance of two MANET routing protocols under varying traffic, density and mobility conditions. We observe, that a rather large fraction of the traffic being carried on the Internet today carries TCP. Thus, Internet traffic has inheritly different characteristics than that of CBR traffic, which is the commonly used...

Recent trends in Wireless Sensor Networks (WSNs) have suggested converging to such being IPv6-based. to this effect, the Internet Engineering Task Force has chartered a Working Group to develop a routing protocol specification, enabling IPv6-based multi-hop Wireless Sensor Networks. This routing protocol, denoted RPL, has been under development for...

Network load-balancers generally either do not takeapplication state into account, or do so at the cost of a central-ized monitoring system. This paper introduces a load-balancerrunning exclusively within the IP forwarding plane, i.e. in anapplication protocol agnostic fashion – yet which still providesapplication-awareness and makes real-time, dec...

Leveraging the performance opportunities offered by programmable hardware, stateless load-balancing architectures allowing line-rate processing are appealing. Moreover, it has been demonstrated that significantly fairer load-balancing can be achieved by an architecture that considers the actual load of application instances when dispatching connect...

In military and tactical missions, operational needs can require different domains and nations in a coalition to federate, to facilitate sharing of resource between domains. On the other hand, data and services need to be protected against unauthorized access. The zero trust paradigm provides principles for securing data and services, based on fine...

Deep neural network (DNN) inference on streaming data requires computing resources to satisfy inference throughput requirements. However, latency and privacy sensitive deep learning applications cannot afford to offload computation to remote clouds because of the implied transmission cost and lack of trust in third-party cloud providers. Among solu...

Optimization in Wireless Networks

In order to dynamically manage and update networking policies in cloud data centers, Virtual Network Functions (VNFs) use, and therefore actively collect, networking state information -and in the process, incur additional control signaling and management overhead, especially in larger data centers. In the meantime, VNFs in production prefer distrib...

Cloud environments require dynamic and adaptive networking policies. It is preferred to use heuristics over advanced learning algorithms in Virtual Network Functions (VNFs) in production becuase of high-performance constraints. This paper proposes Aquarius to passively yet efficiently gather observations and enable the use of machine learning to co...

This paper presents the network load balancing problem, a challenging real-world task for multi-agent reinforcement learning (MARL) methods. Conventional heuristic solutions like Weighted-Cost Multi-Path (WCMP) and Local Shortest Queue (LSQ) are less flexible to the changing workload distributions and arrival rates, with a poor balance among multip...

Cloud environments require dynamic and adaptive networking policies. It is preferred to use heuristics over advanced learning algorithms in Virtual Network Functions (VNFs) in production becuase of high-performance constraints. This paper proposes Aquarius to passively yet efficiently gather observations and enable the use of machine learning to co...

We present a two‐phase methodology to address the problem of optimally deploying indoor wireless local area networks. In the first phase, we use Helmholtz's equation to simulate electromagnetic fields in a typical environment such as an office floor. The linear system which results from the discretization of this partial differential equation is so...

The purpose of network load balancers is to optimize quality of service to the users of a set of servers - basically, to improve response times and to reducing computing resources - by properly distributing workloads. This paper proposes a distributed, application-agnostic, Hybrid Load Balancer (HLB) that - without explicit monitoring or signaling...

Network load balancers are central components in data centers, that distributes workloads across multiple servers and thereby contribute to offering scalable services. However, when load balancers operate in dynamic environments with limited monitoring of application server loads, they rely on heuristic algorithms that require manual configurations...

Network load balancers are central components in data centers, that distributes workloads across multiple servers and thereby contribute to offering scalable services. However, when load balancers operate in dynamic environments with limited monitoring of application server loads, they rely on heuristic algorithms that require manual configurations...

Load-Balancers play an important role in data centers as they distribute network flows across application servers and guarantee per-connection consistency. It is hard however to make fair load balancing decisions so that all resources are efficiently occupied yet not overloaded. Tracking connection states allows to infer server load states and make...

Network load balancers are important components in data centers to provide scalable services. Workload distribution algorithms are based on heuristics, e.g., Equal-Cost Multi-Path (ECMP), Weighted-Cost Multi-Path (WCMP) or naive machine learning (ML) algorithms, e.g., ridge regression. Advanced ML-based approaches help achieve performance gain in d...

Load-Balancers play an important role in data centers as they distribute network flows across application servers and guarantee per-connection consistency. It is hard however to make fair load balancing decisions so that all resources are efficiently occupied yet not overloaded. Tracking connection states allows load balancers to infer server load...

We present a two-phase methodology to address the problem of optimally deploying indoor wireless local area networks. In the first phase, we use Helmholtz's equation to simulate electromagnetic fields in a typical environment such as an office floor. The linear system which results from the discretization of this partial differential equation is so...

Cloud architectures achieve scaling through two main functions: (i) load-balancers, which dispatch queries among replicated virtualized application instances, and (ii) autoscalers, which automatically adjust the number of replicated instances to accommodate variations in load patterns. These functions are often provided through centralized load mon...

This addresses the problem of high-quality packet pacing for constant-rate packet consumption systems, with strict buffering limitations. A mostly-software pacing architecture is developed, which has minimal hardware requirements, satisfied by commodity servers - rendering the proposed solution easily deployable in existing (data-centre) infrastruc...

BIER (Bit-Indexed Explicit Replication) alleviates the operational complexities of multicast protocols (associated to the multicast tree and the incurred state in intermediate routers), by allowing for source-driven, per-packet destination selection, efficient encoding thereof in packet headers, and stateless forwarding along shortest-path multicas...

With the development of large-scale data centers, Virtual Machine (VM) migration is a key component for resource optimization, cost reduction, and maintenance. From a network perspective, traditional VM migration mechanisms rely on the hypervisor running at the destination host advertising the new location of the VM once migration is complete. Howe...

Beyond the transport of uncompressed video over IP networks, defined in standards such as ST2022-6, the ability to build software-based Video Processing Functions (VPF) on commodity hardware and using general purpose Operating Systems is the next logical step in the evolution of the media industry towards an "all-IP" world. In that context, underst...

In data centers, subject to workloads with heterogeneous (and sometimes short) lifetimes, workload migration is a way of attaining a more efficient utilization of the underlying physical machines. To not introduce performance degradation, such workload migration must take into account not only machine resources, and per-task resource requirements,...

Inter-network multicast protocols, which build and maintain multicast trees, incur both explicit protocol signalling, and maintenance of state in intermediate routers in the network. B.I.E.R. (Bit-Indexed Explicit Replication) is a technique which can provide a multicast service yet removes such complexities: intermediate routers are unencumbered b...

Network load-balancers generally either do not take application state into account, or do so at the cost of a centralized monitoring system. This paper introduces a load-balancer running exclusively within the IP forwarding plane, i.e. in an application protocol agnostic fashion – yet which still provides application-awareness and makes real-time,...

This paper studies the routing protocol “Lightweight On-demand Ad hoc Distance-vector Routing Protocol – Next Generation (LOADng)”, designed to enable efficient, scalable and secure routing in low power and lossy networks. As a reactive protocol, it does not maintain a routing table for all destinations in the network, but initiates a route discove...

This document analyzes common security threats to the Optimized Link State Routing Protocol version 2 (OLSRv2) and describes their potential impacts on Mobile Ad Hoc Network (MANET) operations. It also analyzes which of these security vulnerabilities can be mitigated when using the mandatory-to-implement security mechanisms for OLSRv2 and how the v...

LoRa is a long-range, low-power, low-bitrate, wireless telecommunications system, promoted as an infrastructure solution for the Internet of Things: end-devices use LoRa across a single wireless hop to communicate to gateway(s), connected to the Internet and which act as transparent bridges and relay messages between these end-devices and a central...

This document replaces RFC 6779; it contains revisions and extensions to the original document. It defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it describes objects for configuring parameters of the Neighborhood Discovery Protocol (NHDP) process on a r...

This document analyzes security threats to Simplified Multicast Forwarding (SMF), including vulnerabilities of duplicate packet detection and relay set selection mechanisms. This document is not intended to propose solutions to the threats described. In addition, this document updates RFC 7186 regarding threats to the relay set selection mechanisms...

This specification describes an extension to the Optimized Link State Routing Protocol version 2 (OLSRv2) to support multiple routing topologies, while retaining interoperability with OLSRv2 routers that do not implement this extension. This specification updates RFCs 7188 and 7631 by modifying and extending TLV registries and descriptions.

This paper introduces extensions and applications of depth-first forwarding (DFF)—a data forwarding mechanism for use in unreliable networks such as sensor networks and Mobile Ad hoc NETworks with limited computational power and storage, low-capacity channels, device mobility, etc. Routing protocols for these networks try to balance conflicting req...

The link quality mechanism of the Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP) enables "ignoring" some 1-hop neighbors if the measured link quality from that 1-hop neighbor is below an acceptable threshold while still retaining the corresponding link information as acquired from the HELLO message exchange. This allows immedi...

This document reorganizes the naming of already-allocated TLV (type-length-value) types and type extensions in the "Mobile Ad hoc NETwork (MANET) Parameters" registries defined by RFC 5444 to use names appropriately. It has no consequences in terms of any protocol implementation. This document also updates the Expert Review guidelines in RFC 5444,...

This specification describes an extension to the Optimized Link State Routing Protocol version 2 (OLSRv2) to support multiple routing topologies, while retaining interoperability with OLSRv2 routers that do not implement this extension. This specification updates RFCs 7188 and 7631 by modifying and extending TLV registries and descriptions.

The “Light-weight On-demand Ad-hoc Distance-vector Routing Protocol – Next Generation” (LOADng) is a simple, yet efficient and flexible routing protocol, specifically designed for use in lossy networks with constrained devices. A reactive protocol, LOADng – as a basic mode of operation – offers discovery and maintenance of hop-by-hop routes and imp...

This paper analyses the impact of jitter when applied to route discovery in reactive (on-demand) routing protocols. In multi-hop non-synchronized wireless networks, jitter—a small, random variation in the timing of message emission—is commonly employed, as a means to avoid collisions of simultaneous transmissions by adjacent routers over the same c...

The Optimized Link State Routing Protocol version 2 (OLSRv2) includes the ability to assign metrics to links and to use those metrics to allow routing by other than minimum hop count routes. This document provides a historic record of the rationale for, and design considerations behind, how link metrics were included in OLSRv2.

This document analyzes common security threats of the Neighborhood Discovery Protocol (NHDP) and describes their potential impacts on Mobile Ad Hoc Network (MANET) routing protocols using NHDP. This document is not intended to propose solutions to the threats described.

This specification describes extensions to definitions of TLVs used by the Optimized Link State Routing Protocol version 2 (OLSRv2) and the MANET Neighborhood Discovery Protocol (NHDP) to increase their abilities to accommodate protocol extensions. This document updates RFC 7181 (OLSRv2) and RFC 6130 (NHDP).

This specification describes version 2 of the Optimized Link State Routing Protocol (OLSRv2) for Mobile Ad Hoc Networks (MANETs).

This document revises, extends, and replaces RFC 6622. It describes general and flexible TLVs for representing cryptographic Integrity Check Values (ICVs) and timestamps, using the generalized Mobile Ad Hoc Network (MANET) packet/message format defined in RFC 5444. It defines two Packet TLVs, two Message TLVs, and two Address Block TLVs for affixin...

This document specifies integrity and replay protection for the Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP) and the Optimized Link State Routing Protocol version 2 (OLSRv2). This protection is achieved by using an HMAC-SHA-256 Integrity Check Value (ICV) TLV and a Timestamp TLV based on Portable Operating System Interface (...

This document defines the Management Information Base (MIB) module for configuring and managing the Optimized Link State Routing Protocol version 2 (OLSRv2). The OLSRv2-MIB module is structured into configuration information, state information, performance information, and notifications. This additional state and performance information is useful f...

This specification updates the Optimized Link State Routing Protocol version 2 (OLSRv2) with an optimization to improve the selection of routing multipoint relays. The optimization retains full interoperability between implementations of OLSRv2 with and without this optimization.

paper proposes an extension to reactive routing protocol, for efficient construction of a collection tree for data acquisition in sensor networks. The Lightweight On-Demand Ad hoc Distance Vector Routing Protocol-Next Generation (LOADng) is a reactive distance vector protocol which is intended for use in mobile ad hoc networks and low-power and los...

Data delivery across a multi-hop low-power and lossy networks (LLNs) is a challenging task: devices participating in such a network have strictly limited computational power and storage, and the communication channels are of low capacity, time-varying and with high loss rates. Consequently, routing protocols finding paths through such a network mus...

This paper explores the cooperation between the new standards for "Low Power and Lossy Networks'' (LLNs): IETF RFC 6971, denoted ``Depth-First Forwarding in Unreliable Networks'' (DFF) and the ITU-T standardised routing protocol "LOADng''. DFF is a data-forwarding mechanism for increasing reliability of data delivery in networks with dynamic topolo...

Routing protocol is a critical component of Low-power and Lossy Networks for Smart Grid. The protocols are used for data forwarding, which includes data acquisition, information dissemination, etc. This paper evaluates two main routing protocols used for Low-power and Lossy Networks: RPL and LOADng, to understand their strengths and limitations. Ob...

“The Trickle Algorithm” is conceived as an adaptive mechanism for allowing efficient and reliable information sharing among nodes, communicating across a lossy and shared medium. Its basic principle is, for each node, to monitor transmissions from its neighbours, compare what it receives with its current state, and schedule future transmissions acc...

Jittering (a small, random variation in timing of control message emission) is widely used in protocols for wireless communication, in order to avoid simultaneous packet transmissions over the same channel by adjacent nodes in the network. Used for both regularly scheduled packets, for event-triggered packets, and for scheduled resets in the networ...

Jitter is a small, random variation of timing before message emission that is widely used in non-synchronized wireless communication. It is employed to avoid collisions caused by simultaneous transmissions by adjacent nodes over the same channel. In reactive (on-demand) routing protocols, such as AODV and LOADng, it is recommended to use jitter dur...

A derivative of AODV, denoted LOADng, is proposed for use in very constrained environment, sacrificing a number of features from AODV for the benefit of smaller control messages and simpler processing logic. Among these sacrifices is intermediate route replies. This paper presents an alternative to intermediate router replies, denoted Smart Route R...

After more than a decade of research and standardization, Mobile Ad Hoc NETworks (MANET) are finding their place in real-world deployments, such as in community, tactical and vehicular networks. Becoming so present in "textit{the real world}" also means that MANETs, and the protocols operating them, are affronted with a more hostile environment, wh...

The Ad hoc On-demand Distance-Vector routing protocol (AODV) was published in 2003 by the IETF, as experimental RFC 3561. This routing protocol was one of four routing protocols, developed by the IETF for use in mobile ad hoc networks (MANETs) -- with the other being DSR, TBRPF and OLSR. As operational experiences with these protocols accumulated,...

This paper proposes an extension to the "LLN On-demand Ad hoc Distance-vector Routing Protocol - Next Generation" (LOADng), for efficient construction of a collection tree for data acquisition in sensor networks. The extension uses the mechanisms from LOADng, imposes minimal overhead and complexity, and enables a deployment to efficiently support b...

This document describes general and flexible TLVs for representing cryptographic Integrity Check Values (ICVs) (i.e., digital signatures or Message Authentication Codes (MACs)) as well as timestamps, using the generalized Mobile Ad Hoc Network (MANET) packet/message format defined in RFC 5444. It defines two Packet TLVs, two Message TLVs, and two A...

Recent trends in Wireless Sensor Networks (WSNs) have suggested converging to such being IPv6-based. To this effect, the Internet Engineering Task Force has chartered a Working Group to develop a routing protocol specification, enabling IPv6-based multi-hop Wireless Sensor Networks. This routing protocol, denoted “IPv6 Routing Protocol for Low Powe...

This paper proposes a simple mechanism for enabling basic delay tolerant networking with off-the-shelf MANET routing protocols -- with the objective being to enable trading off slightly longer data delivery delays against resilience to a temporary lack of connectivity between a router and the ultimate destination of an IP data gram. As part of test...

This document describes the LLN Ad hoc On-Demand (LOAD) distance vector routing protocol - Next Generation, a reactive routing protocol intended for use in Low power Lossy Networks (LLN). The protocol is derived from AODV and extended for use in LLNs.

If deployments of Mobile Ad Hoc Networks (MANETs) are to become common outside of purely experimental settings, protocols operating such MANETs must be able to preserve network integrity, even when faced with careless or malicious participants. A first step towards protecting a MANET is to analyze the vulnerabilities of the routing protocol(s), man...

This memorandum proposes a simple mechanism for enabling basic delay tolerant networking with off-the-shelf MANET routing protocols - with the objective being to enable trading off slightly longer data delivery delays against resilience to a temporary lack of connectivity between a router and the ultimate destination of an IP datagram. As part of t...

Routing protocols for sensor networks are often designed with explicit assumptions, serving to simplify design and reduce the necessary energy, processing and communications requirements. Different protocols make different assumptions - and this paper considers those made by the designers of RPL - an IPv6 routing protocol for such networks, develop...

With RPL - the “IPv6 Routing Protocol for Low-power Lossy Networks” - emerging as a Proposed Standard “Request For Comment” (RFC) in the Internet Engineering Task Force (IETF) after a ~2-year development cycle, this paper presents a critical evaluation of the resulting protocol and its applicability and limits. The paper presents a selection of obs...

This document describes a 1-hop and symmetric 2-hop neighborhood discovery protocol (NHDP) for mobile ad hoc networks (MANETs).

The Trickle algorithm allows nodes in a lossy shared medium (e.g., low-power and lossy networks) to exchange information in a highly robust, energy efficient, simple, and scalable manner. Dynamically adjusting transmission windows allows Trickle to spread new information on the scale of link-layer transmission times while sending only a few message...

This memorandum presents a selection of observations and experiences acquired when producing a prototype implementation of RPL as well as an evaluation of the applicability of this protocol for various specific ``real-world'' deployments.

Heterogeneous networks combining both wired and wireless components - fixed routers as well as mobile routers - emerge as wireless mesh networks are being deployed. Such heterogeneity is bound to become more and more present in the near future as mobile ad hoc networking becomes a reality. While it is possible to cope with heterogeneity by employin...

This chapter explores techniques that enable efficient link state routing on compound networks. These techniques rely on the selection and maintenance of a subset of links in the network (i.e. an overlay) along which the different operations of link-state routing can be performed more efficiently. This chapter provides a formal analysis of such tec...

This paper addresses the issues of automatic address and prefix configuration of MANET routers. Specifically, the paper analyzes the differences between “classic IP networks” and MANETs, emphasizing the interface, link, topology, and addressing assumptions present in “classic IP networks”. The paper presents a model for how this can be matched to t...

The IEEE WAVE protocol suite is providing communications services to applications in vehicular networks, by way of promising support for two protocol stacks: the Wave Short Message Protocol (WSMP) and IPv6. While WSMP is developed within the IEEE 1609 family of standards, the authors of this paper assert, that considerations for IPv6 operation for...

Recent trends have suggested convergence to Wireless Sensor Networks (WSNs) becoming IPv6-based. To this effect, the Internet Engineering Task Force has chartered a Working Group to develop a routing protocol specification, enabling IPv6-based multi-hop WSNs. The current effort of this working group is development of a unicast routing protocol deno...

Public community Mobile Ad Hoc NETworks (MANETs), such as the "Funkfeuer" or "Freifunk" networks, scale up to several hundreds of routers, connecting users with each other, and with the Internet. As MANETs are typically operated over wireless channels (e.g. WiFi), access to these networks is granted to anyone in the radio range of another router in...

Recent trends in Wireless Sensor Networks (WSNs) have suggested converging to such being IPv6-based. to this effect, the Internet Engineering Task Force has chartered a Working Group to develop a routing protocol specification, enabling IPv6-based multi-hop Wireless Sensor Networks. This routing protocol, denoted RPL, has been under development for...

Mobile Ad hoc NETworks (MANETs) are leaving the confines of research laboratories, to find place in real-world deployments. Outside specialized domains (military, vehicular, etc.), city-wide communitynetworks are emerging, connecting regular Internet users with each other, and with the Internet, via MANETs. Growing to encompass more than a handful...

Mobile Ad hoc NETworks (MANETs) are leaving the confines of research laboratories, to find place in real-world deployments. Outside specialized domains (military, vehicular, etc.), city-wide communitynetworks are emerging, connecting regular Internet users with each other, and with the Internet, via MANETs. Growing to encompass more than a handful...

This memorandum presents security mechanisms for router and link admittance control in OLSRv2. Digitally signing OLSRv2 control messages allows recipient routers to -- individually -- choose to admit or exclude the originating router for when populating link-state databases, calculating MPR sets etc. By additionally embedding signatures for each ad...

Mobile Ad Hoc NETworks (MANETs) are generally thought of as infrastructureless and largely ``un-managed'' network deployments, capable of accommodating highly dynamic network topologies. Yet, while the network infrastructure may be ``un-managed'', monitoring the network performance and setting configuration parameters once deployed, remains importa...

Mobile Ad hoc NETworks (MANETs) are leaving the confines of research laboratories, to find place in real-world deployments. Outside specialized domains (military, vehicular, etc.), city-wide community-networks are emerging, connecting regular Internet users with each other, and with the Internet, via MANETs. Growing to encompass more than a handful...

This document compares two protocols, MHVB and NHDP. While both protocols are intended for wireless multi-hop ad hoc networks, they differ fundamentally, both in operation and in purpose: MHVB is a location-based, general-purpose transport protocol for network wide information dissemination, whereas NHDP is a protocol enabling a router to acquire i...