Publications
Technical reports
Norske mobilnett i 2022
In Tilstandsrapport fra Simula Metropolitan Center for Digital Engineering, Center for Resilient Networks and Applications. Oslo, Norway: Simula, 2023.Status: Published
Norske mobilnett i 2022
Denne rapporten er utarbeidet av Center for Resilient Networks and Applications (CRNA), som er en del av Simula Metropolitan Center for Digital Engineering. CRNA driver grunnleggende forskning innen robusthet og sikkerhet i nettverk med mandat og finansiering fra kommunal- og moderniseringsdepartementet. Senteret produserer en årlig rapport om tilstanden i norske mobilnett. Årets rapport er den tiende i rekken.
Afilliation | Communication Systems |
Project(s) | The Center for Resilient Networks and Applications |
Publication Type | Technical reports |
Year of Publication | 2023 |
Secondary Title | Tilstandsrapport fra Simula Metropolitan Center for Digital Engineering, Center for Resilient Networks and Applications |
Date Published | 05/2023 |
Publisher | Simula |
Place Published | Oslo, Norway |
ISBN Number | 978-82-92593-38-7 |
Keywords | Mobile networks, Performance, Stability |
Notes | |
URL | https://www.simulamet.no/sites/default/files/norske_mobilnett2022.pdf |
Research Notes |
Technical reports
Norske mobilnett i 2021 – Tilstandsrapport fra Centre for Resilient Networks and Applications
Oslo/Norway: Simula Metropolitan Center for Digital Engineering, Centre for Resilient Networks and Applications (CRNA), 2022.Status: Published
Norske mobilnett i 2021 – Tilstandsrapport fra Centre for Resilient Networks and Applications
Denne rapporten er utarbeidet av Center for Resilient Networks and Applications (CRNA), som er en del av Simula Metropolitan Center for Digital Engineering. CRNA driver grunn- leggende forskning innen robusthet og sikker- het i nettverk med mandat og finansiering fra Kommunal- og moderniseringsdepartementet. Senteret produserer en årlig rapport om tilstan- den i norske mobilnett. Årets rapport er den niende i rekken.
Afilliation | Communication Systems |
Project(s) | NorNet, The Center for Resilient Networks and Applications, Simula Metropolitan Center for Digital Engineering, Simula Metropolitan Center for Digital Engineering, SMIL: SimulaMet Interoperability Lab |
Publication Type | Technical reports |
Year of Publication | 2022 |
Publisher | Simula Metropolitan Center for Digital Engineering, Centre for Resilient Networks and Applications (CRNA) |
Place Published | Oslo/Norway |
ISBN Number | 82-92593-36-5 |
URL | https://www.simula.no/sites/default/files/norske_mobilnett_i_2021.pdf |
Book Chapter
Using Bluetooth for contact tracing
In Smittestopp − A Case Study on Digital Contact Tracing, 81-98. Vol. 11. Cham: Springer International Publishing, 2022.Status: Published
Using Bluetooth for contact tracing
Afilliation | Communication Systems |
Project(s) | No Simula project |
Publication Type | Book Chapter |
Year of Publication | 2022 |
Book Title | Smittestopp − A Case Study on Digital Contact Tracing |
Volume | 11 |
Chapter | 5 |
Pagination | 81-98 |
Publisher | Springer International Publishing |
Place Published | Cham |
Journal Article
A Multi-Perspective Study of Internet Performance during the COVID-19 Outbreak
Arxiv (2021).Status: Published
A Multi-Perspective Study of Internet Performance during the COVID-19 Outbreak
Afilliation | Communication Systems |
Project(s) | Simula Metropolitan Center for Digital Engineering, GAIA |
Publication Type | Journal Article |
Year of Publication | 2021 |
Journal | Arxiv |
Publisher | Arxiv |
Place Published | Arrxiv.org |
Keywords | COVID, Internet, network |
DOI | 10.48550/arXiv.2101.05030 |
Nationwide rollout reveals efficacy of epidemic control through digital contact tracing
Nature Communications 12 (2021).Status: Published
Nationwide rollout reveals efficacy of epidemic control through digital contact tracing
Afilliation | Communication Systems, Scientific Computing, Machine Learning |
Project(s) | The Center for Resilient Networks and Applications, Department of Data Science and Knowledge Discovery , Department of Computational Physiology |
Publication Type | Journal Article |
Year of Publication | 2021 |
Journal | Nature Communications |
Volume | 12 |
Number | 5918 |
Publisher | Springer Nature |
DOI | 10.1038/s41467-021-26144-8 |
Technical reports
Norske mobilnett i 2017
Simula Research Laboratory, 2018.Status: Published
Norske mobilnett i 2017
Afilliation | Communication Systems |
Project(s) | The Center for Resilient Networks and Applications, Simula Metropolitan Center for Digital Engineering |
Publication Type | Technical reports |
Year of Publication | 2018 |
Date Published | 05/2018 |
Publisher | Simula Research Laboratory |
Proceedings, refereed
Investigating Packet Loss in Mobile Broadband Networks under Mobility
In IFIP Networking, 2016.Status: Published
Investigating Packet Loss in Mobile Broadband Networks under Mobility
Mobile broadband (MBB) connections are often exposed to varying network conditions under mobility scenarios, which can result in packet loss and higher end-to-end delays. Such performance degradation in turn can adversely impact the user experience. In this paper, we study packet loss characteristics of MBB networks under mobility using six measurement nodes that are placed on regional and inter-city trains in Norway for a period of seven months. Our findings show that packet loss is significantly higher for mobility scenarios compared to the stationary. In order to understand the cause of packet loss, we investigate Radio Access Technology (RAT) changes, temporary loss of service, and changes in cells and location area codes (LAC). We surprisingly find that almost all periods with RAT changes involve packet loss. We also observe that 70% of the overall loss happens in periods with RAT changes or temporary loss of service. Further, one third of RAT changes involve connection termination. Our findings highlight the importance of radio access network (RAN) planning and configuration, and provide guidelines to alleviate packet loss in MBB networks.
Afilliation | Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2016 |
Conference Name | IFIP Networking |
Date Published | 05/2016 |
MULTEX: multiple PDN connections in LTE and beyond for enhanced routing and services
In Proceedings of the 5th Workshop on All Things Cellular: Operations, Applications and Challenges, 2016.Status: Published
MULTEX: multiple PDN connections in LTE and beyond for enhanced routing and services
Afilliation | Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2016 |
Conference Name | Proceedings of the 5th Workshop on All Things Cellular: Operations, Applications and Challenges |
Pagination | 13-18 |
Proceedings, refereed
Dissecting Packet Loss in Mobile Broadband Networks from the Edge
In IEEE INFOCOM. IEEE, 2015.Status: Published
Dissecting Packet Loss in Mobile Broadband Networks from the Edge
This paper demonstrates that end-to-end active measurements can give invaluable insights into the nature and characteristics of packet loss in cellular networks. We conduct a large-scale measurement study of packet loss in four UMTS networks. The study is based on active measurements from hundreds of measurement nodes over a period of one year. We find that a significant fraction of loss occurs during pathological and normal Radio Resource Control (RRC) state transitions. The remaining loss exhibits pronounced diurnal patterns and shows a relatively strong correlation between geographically diverse measurement nodes. Our results indicate that the causes of a significant part of the remaining loss lie beyond the radio access network.
Afilliation | , Communication Systems, Communication Systems |
Project(s) | The Center for Resilient Networks and Applications |
Publication Type | Proceedings, refereed |
Year of Publication | 2015 |
Conference Name | IEEE INFOCOM |
Date Published | 04/2015 |
Publisher | IEEE |
Investigating Excessive Delays in Mobile Broadband Networks
In ACM SIGCOMM 2015 Workshop on All Things Cellular: Operations, Applications and Challenges. ACM, 2015.Status: Published
Investigating Excessive Delays in Mobile Broadband Networks
Systematic monitoring of performance characteristics of mobile broadband networks can help users, operators, and regulators understand this increasingly critical infrastructure. We report the results of a measurement study of round trip delays in two mobile networks in Norway using over 200 geographically distributed subscriptions for a period of one month. In general, we find high variation in delay within the same radio access type and RRC state. Across both networks we study, we observe connections with round trip delays of several seconds, often multiple times per hour, that are more frequent when nodes are moving. Correlating these extreme delay events with available metadata, we find they are related to handovers, radio state transitions, and retransmissions at the link and physical layers.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2015 |
Conference Name | ACM SIGCOMM 2015 Workshop on All Things Cellular: Operations, Applications and Challenges |
Publisher | ACM |
Technical reports
Robusthet i norske mobilnett Tilstandsrapport 2014
Oslo: Simula, 2015.Status: Published
Robusthet i norske mobilnett Tilstandsrapport 2014
Afilliation | Communication Systems, Communication Systems |
Project(s) | The Center for Resilient Networks and Applications |
Publication Type | Technical reports |
Year of Publication | 2015 |
Date Published | 04/2015 |
Publisher | Simula |
Place Published | Oslo |
Proceedings, refereed
Measuring and Comparing Internet Path Stability in IPv4 and IPv6
In Proceedings of the 5th IEEE International Conference on the Network of the Future (NoF). Paris/France: IEEE, 2014.Status: Published
Measuring and Comparing Internet Path Stability in IPv4 and IPv6
In just about 4 years, IPv6 will celebrate its 20th anniversary. While the protocol itself is already quite old, its deployment has only recently picked up speed. Not so many Internet service providers offer direct IPv6 connectivity to their customers, yet. Clearly, when IPv6 is available to customers, they expect that IPv6 offers at least the same - or even better - stability of connections in comparison to IPv4. The main goal of this paper is to investigate whether this is true today. In our paper, we present up-to-date measurement results on the stability of IPv4 and IPv6 paths in the real Internet, based on machines that are distributed over a large geographical area, as part of the NorNet Core testbed infrastructure for multi-homed systems. The measurements not only cover high-speed research networks, but also consumer-grade ADSL connections - i.e. the ISP connection types of "normal" end-users - as well as a broad range of different ISPs. The measurements show that IPv6 paths are less stable than corresponding IPv4 paths. We also find that the use of load balancing is more prevalent in IPv6 than in IPv4.
Afilliation | , Communication Systems, Communication Systems |
Project(s) | NorNet, The Center for Resilient Networks and Applications |
Publication Type | Proceedings, refereed |
Year of Publication | 2014 |
Conference Name | Proceedings of the 5th IEEE International Conference on the Network of the Future (NoF) |
Date Published | December |
Publisher | IEEE |
Place Published | Paris/France |
Keywords | Conference |
Measuring the QoS Characteristics of Operational 3G Mobile Broadband Networks
In Proceedings of the 4th International Workshop on Protocols and Applications with Multi-Homing Support (PAMS). Victoria, British Columbia/Canada: IEEE, 2014.Status: Published
Measuring the QoS Characteristics of Operational 3G Mobile Broadband Networks
Today, many smart phones and tablets have multiple interfaces (i.e. WLAN and 3G). These multiple interfaces can be utilized simultaneously by a multi-path transport protocol to provide bandwidth aggregation or reliability. However, in order to design efficient multi-path scheduling and congestion control strategies, it is crucial to understand the behaviour and properties of the underlying paths first. WLAN links have already been studied extensively in the literature. Therefore, in this paper, we focus on Mobile Broadband (MBB) networks that are in use today. We utilized noun{NorNet Edge} nodes that are connected to up to five different 3G ISPs (UMTS and CDMA2000), hence, providing a realistic view on the QoS characteristics that are experienced by end-users of these MBB networks. We present QoS characteristics (e.g. bandwidth, delay and loss) and discuss our observations. Our results shed light on what a multi-path transport endpoint has to expect - and to efficiently cope with - when using today's MBB networks as transport paths.
Afilliation | Communication Systems, , Communication Systems |
Project(s) | The Center for Resilient Networks and Applications |
Publication Type | Proceedings, refereed |
Year of Publication | 2014 |
Conference Name | Proceedings of the 4th International Workshop on Protocols and Applications with Multi-Homing Support (PAMS) |
Date Published | May |
Publisher | IEEE |
Place Published | Victoria, British Columbia/Canada |
Keywords | Workshop |
Measuring the Reliability of Mobile Broadband Networks
In Proceedings of the 14th ACM Internet Measurement Conference (IMC'14). ACM, 2014.Status: Published
Measuring the Reliability of Mobile Broadband Networks
Mobile broadband networks play an increasingly important role in society, and there is a strong need for independent assessments of their robustness and performance. A promising source of such information is active end-to-end measurements. It is, however, a challenging task to go from individual measurements to an assessment of network reliability, which is a complex notion encompassing many stability and performance related metrics. This paper presents a framework for measuring the user-experienced reliability in mobile broadband networks. We argue that reliability must be assessed at several levels, from the availability of the network connection to the stability of application performance. Based on the proposed framework, we conduct a large-scale measurement study of reliability in 5 mobile broadband networks. The study builds on active measurements from hundreds of measurement nodes over a period of 10 months. The results show that the reliability of mobile broadband networks is lower than one could hope: more than 20% of connections from stationary nodes are unavailable more than 10 minutes per day. There is, however, a significant potential for improving robustness if a device can connect simultaneously to several networks. We find that in most cases, our devices can achieve 99.999% ("five nines") connection availability by combining two operators. We further show how both radio conditions and network configuration play important roles in determining reliability, and how external measurements can reveal weaknesses and incidents that are not always captured by the operators' existing monitoring tools.
Afilliation | , Communication Systems, Communication Systems |
Project(s) | The Center for Resilient Networks and Applications |
Publication Type | Proceedings, refereed |
Year of Publication | 2014 |
Conference Name | Proceedings of the 14th ACM Internet Measurement Conference (IMC'14) |
Publisher | ACM |
Journal Article
NorNet Core - A Multi-Homed Research Testbed
Computer Networks Special Issue: Future Internet Testbeds (2014): 75-87.Status: Published
NorNet Core - A Multi-Homed Research Testbed
Over the last decade, the Internet has grown at a tremendous speed in both size and complexity. Nowadays, a large number of important services - for instance e-commerce, healthcare and many others - depend on the availability of the underlying network. Clearly, service interruptions due to network problems may have a severe impact. On the long way towards the Future Internet, the complexity will grow even further. Therefore, new ideas and concepts must be evaluated thoroughly, and particularly in realistic, real-world Internet scenarios, before they can be deployed for production networks. For this purpose, various testbeds - for instance PlanetLab, GpENI or G-Lab - have been established and are intensively used for research. However, all of these testbeds lack the support for so-called multihoming. Multi-homing denotes the connection of a site to multiple Internet service providers, in order to achieve redundancy. Clearly, with the need for network availability, there is a steadily growing demand for multi-homing. The idea of the NorNet Core project is to establish a Future Internet research testbed with multi-homed sites, in order to allow researchers to perform experiments with multi-homed systems. Particular use cases for this testbed include realistic experiments in the areas of multi-path routing, load balancing, multi-path transport protocols, overlay networks and network resilience. In this paper, we introduce the NorNet Core testbed as well as its architecture.
Afilliation | , Communication Systems, Communication Systems, Communication Systems |
Project(s) | NorNet, The Center for Resilient Networks and Applications |
Publication Type | Journal Article |
Year of Publication | 2014 |
Journal | Computer Networks |
Volume | Special Issue: Future Internet Testbeds |
Number | 61 |
Pagination | 75-87 |
Publisher | Elsevier |
DOI | 10.1016/j.bjp.2013.12.035 |
The Nornet Edge Platform for Mobile Broadband Measurements
Computer Networks (2014).Status: Published
The Nornet Edge Platform for Mobile Broadband Measurements
We present Nornet Edge (NNE), a dedicated infrastructure for measurements and experimentation in mobile broadband networks. NNE is unprecedented in size, consisting of more than 400 measurement nodes geographically distributed all over Norway. Each measurement node is a Linux-based embedded computer, and is connected to multiple mobile broadband providers. In addition, NNE includes an extensive backend system for deploying and managing experiments and collecting data. NNE makes it possible to run long-term measurement experiments to assess and compare quality and performance across different network operators on a national scale. Particular focus is put on allowing experiments to run in parallel on multiple network connections, and on collecting rich context information related to the experiments. In this paper we give a detailed presentation of NNE, and describe three different measurement experiments that illustrate how the infrastructure can be used. We also provide a roadmap for further development of NNE.
Afilliation | , Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2014 |
Journal | Computer Networks |
Number | 61 |
Keywords | Conference, Internal Seminar, University of Oslo, Workshop |
DOI | 10.1016/j.bbr.2011.03.031 |
Technical reports
Robusthet i norske mobilnett Tilstandsrapport 2013
Oslo: Simula, 2014.Status: Published
Robusthet i norske mobilnett Tilstandsrapport 2013
Afilliation | Communication Systems, Communication Systems |
Project(s) | The Center for Resilient Networks and Applications |
Publication Type | Technical reports |
Year of Publication | 2014 |
Date Published | 02/2014 |
Publisher | Simula |
Place Published | Oslo |
Proceedings, refereed
Geography Matters: Building an Efficient Transport Network for a Better Video Conferencing Experience
In CoNEXT. ACM, 2013.Status: Published
Geography Matters: Building an Efficient Transport Network for a Better Video Conferencing Experience
Some network applications have requirements that exceed the service levels offered by the best-effort Internet. Several network-layer Quality of Service architectures with ex- tended service levels have been designed, but the massive scale and distributed nature of the Internet have prohibited their wide deployment. It now seems clear that the special needs of demanding applications must be met through other approaches. This paper describes how incrementally- deployed innovative solutions at the network level can con- tribute to an improved service for a particular type of applications, namely high-quality, wide-area video conferencing. We have built a global IP network, aiming to give users a better video conferencing experience primarily through packet loss reduction in transport networks. The key concept in our approach is a well-provisioned network-layer overlay, combined with geography-based “cold potato” BGP routing. Through an extensive set of experiments we show how our design choices impact routing and data plane behavior in the network, and demonstrate that we are able to significantly reduce packet loss compared to wide-area transport through global transit providers.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2013 |
Conference Name | CoNEXT |
Pagination | 369-380 |
Date Published | December |
Publisher | ACM |
ISBN Number | 978-1-4503-2101-3 |
Keywords | Conference |
Increased Robustness With Interface Based Permutation Routing
In IEEE ICC 2013, 2013.Status: Published
Increased Robustness With Interface Based Permutation Routing
A prime objective of fault tolerant routing methods is the availability of multiple routing options at each hop. The methods that are currently implemented in IP networks, such as Equal-Cost Multi-Path (ECMP) and Loop Free Alternates (LFA), share the following four properties: First, they work with a hop-by-hop forwarding strategy optimized for the fault free case. Second, they do not require information associated with network faults included in the packet header. Third, they do not form forwarding loops, even under multiple failures in the network. Finally, they are compatible with standard link state routing protocols. However, ECMP and LFA give very poor fault coverage; in most cases fewer than 50% of primary next-hops are protected when using typical link weight settings. This paper presents a new routing method that combines the concept of permutation routing with interface-specific forwarding. Our method results in a routing strategy that strictly adheres to the four stated design properties. Through experiments we show that we protect more than 97% of the primary next-hops for all tested ISP networks.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2013 |
Conference Name | IEEE ICC 2013 |
Keywords | Conference |
Preempting State Promotions to Improve Application Performance in Mobile Broadband Networks
In 8th ACM Workshop on Mobility in the Evolving Internet Architecture (MobiArch). ACM Sigmobile, 2013.Status: Published
Preempting State Promotions to Improve Application Performance in Mobile Broadband Networks
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2013 |
Conference Name | 8th ACM Workshop on Mobility in the Evolving Internet Architecture (MobiArch) |
Date Published | October |
Publisher | ACM Sigmobile |
Routing With Joker Links for Maximized Robustness
In Proceedings of IFIP Networking 2013 Conference. IEEE, 2013.Status: Published
Routing With Joker Links for Maximized Robustness
IP Fast Reroute methods that are currently deployed in link-state routing protocols with hop-by-hop forwarding, such as Equal-Cost Multi-Path (ECMP) and Loop Free Alternates (LFA), share two common important properties. First, they never form forwarding loops, even when there are multiple independent failures in the network. Second, they do not introduce non- standard packet marking to convey information associated with network faults. However, these Fast Reroute methods give very poor fault coverage; in most cases below 50% of links are protected when using typical link weight settings. This paper presents a new routing method that combines the concept of permutation routings with joker links, called joker-capable permutation routings. Our method results in a routing strategy that shares with ECMP and LFA the stated important properties. Through experiments we show that we protect more than 95% of links for all tested ISP networks. Measurements also show that our method is computationally feasible and performs traffic distribution efficiently under high fluctuations of traffic demands.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2013 |
Conference Name | Proceedings of IFIP Networking 2013 Conference |
Pagination | 1-9 |
Publisher | IEEE |
Keywords | Conference |
Miscellaneous
NorNet Workshop Welcome
2013.Status: Published
NorNet Workshop Welcome
Afilliation | , Communication Systems |
Publication Type | Miscellaneous |
Year of Publication | 2013 |
Keywords | Workshop |
Notes | Workshop Welcome of the 1st NorNet Users Workshop (NNUW-1) |
Journal Article
BGP Churn Evolution: a Perspective From the Core
IEEE/ACM Transactions on Networking 20 (2012): 571-584.Status: Published
BGP Churn Evolution: a Perspective From the Core
The scalability limitations of BGP have been a major concern lately. An important aspect of this issue is the rate of routing updates (churn) that BGP routers must process. This paper presents an analysis of the evolution of churn in four networks at the backbone of the Internet over a period of seven years and eight months, using BGP update traces from the RouteViews project. The churn rate varies widely over time and between networks. Instead of descriptive ``black-box'' statistical analysis, we take an exploratory data analysis approach attempting to understand the reasons behind major observed characteristics of the churn time series. We find that duplicate announcements is a major churn contributor, responsible for most large spikes. Remaining spikes are mostly caused by routing incidents that affect a large number of prefixes simultaneously. More long-term intense periods of churn, on the other hand, are caused by misconfigurations or other special events at or close to the monitored AS. After filtering pathologies and effects that are not related to the long-term evolution of churn, we analyze the remaining ``baseline'' churn and find that it is increasing at a rate that is similar to the growth of the number of Autonomous Systems.
Afilliation | , Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2012 |
Journal | IEEE/ACM Transactions on Networking |
Volume | 20 |
Number | 2 |
Pagination | 571-584 |
Date Published | April |
Permutation Routing for Increased Robustness in IP Networks
Networking 1 (2012): 217-231.Status: Published
Permutation Routing for Increased Robustness in IP Networks
We present Permutation Routing as a method for increased robustness in IP networks with traditional hop-by-hop forwarding. Permutation Routing treats routers involved in traffic forwarding as a sequence of resources, and creates permutations of these resources that give several forwarding options. We introduce Permutation Routing as a concept, and use it to create routings where we seek to maximize single link fault coverage. Analogous to the IETF standardized Loop-Free Alternate (LFA), Permutation Routing can easily be implemented for OSPF or IS-IS networks to augment existing ECMP forwarding with additional loop-free forwarding entries for improved load balancing or fault tolerance. Our evaluations show that Permutation Routing can increase single link fault coverage by up to 28% compared to LFA in inferred network topologies.
Afilliation | , Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2012 |
Journal | Networking |
Volume | 1 |
Number | LNCS 7289 |
Pagination | 217-231 |
Publisher | Springer Berlin Heidelberg |
Proceedings, refereed
Characterizing Delays in Norwegian 3G Networks
In Proceedings PAM 2012. Vol. 7192. Lecture Notes in Computer Science 7192. Springer, 2012.Status: Published
Characterizing Delays in Norwegian 3G Networks
This paper presents a first look at long-term delay measurements from data connections in 3 Norwegian 3G Networks. We have performed active measurements for more than 6 months from 90 voting locations used in a trial with electronic voting during this fall's regional elections. Our monitors are geographically spread across all of Norway, and give an unprecedented view of the performance and stability of the total 3G infrastructure of a country. In this paper, we focus on delay characteristics. We find large differences in delay between different monitors. More interestingly, we observe that the delay characteristics of the different operators are very different, pointing to operator-specific network design and configurations as the most important factor for delays.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2012 |
Conference Name | Proceedings PAM 2012 |
Volume | 7192 |
Publisher | Springer |
On Randomness in ISP-Friendly P2P Applications
In The 26th IEEE International Conference on Advanced Information Networking and Applications, AINA-2012. IEEE, 2012.Status: Published
On Randomness in ISP-Friendly P2P Applications
P2P networking is a popular technology for sharing large files efficiently without using powerful servers. The goal for a P2P file sharing application is to minimize the download time experienced by the peers. However, the efficiency of a P2P network comes at the expense of excessive network utilization. ISPs want to control the network utilization of P2P applications, and in particular it is desirable to minimize the inter-ISP traffic. The often contradicting interests of applications and network owners have led to the search for an ISP-friendly P2P application that reduces inter-ISP traffic while maintaining the high file-sharing efficiency. Existing solutions propose to localize most of the P2P traffic within the ISP, while randomly selecting a few external peers to ensure the global spread of content. However, these proposals disregard the inherent randomness that will naturally exist in P2P systems. In this paper, we analyze the different sources of inherent randomness in ISP-friendly P2P systems, and show that they can have a significant impact on performance, and therefore must be taken into account when designing new solutions.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2012 |
Conference Name | The 26th IEEE International Conference on Advanced Information Networking and Applications, AINA-2012 |
Date Published | March |
Publisher | IEEE |
PreeN: Improving Steady-State Performance of ISP-Friendly P2P Applications
In 13th International conference on Distributed Computing and Networking, ICDCN 2012. Vol. 7129. Lecture Notes in Computer Science 7129. Springer, 2012.Status: Published
PreeN: Improving Steady-State Performance of ISP-Friendly P2P Applications
Much effort has been put into making P2P applications ISP-friendly, i.e. finding a solution that reduces inter-ISP traffic while maintaining the high file-sharing efficiency of existing P2P applications. Related works have analyzed different ISP-friendly P2P solutions by simulations. However, most of these simulation models have two common assumptions; 1) the peer arrival process follows a flash-crowd scenario, 2) the distribution of peers follows a uniform distribution. Most of the time, both these assumptions are not true for a P2P network. In this paper we show that the peer arrival process and the distribution of peers have a significant effect on the simulation results. We also show that solutions perform differently, e.g. in terms of the amount of inter-ISP traffic and download time, in a flash crowd scenario than in a steady state, limiting the applicability of the results and conclusions reported in previous works. Based on this new insight, we propose a Preemptive Neighbor Selection (PreeN) that makes an ISP-friendly P2P application efficient in steady state scenarios.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2012 |
Conference Name | 13th International conference on Distributed Computing and Networking, ICDCN 2012 |
Volume | 7129 |
Date Published | January |
Publisher | Springer |
Technical reports
Increased Robustness With Interface Based Permutation Routing
Simula Research Laboratory, 2012.Status: Published
Increased Robustness With Interface Based Permutation Routing
A prime objective of fault tolerant routing methods is the availability of multiple routing options at each hop. The methods that are currently implemented in IP networks, such as Equal-Cost Multi-Path (ECMP) and Loop Free Alternates (LFA), share the following four properties: First, they work with a hop-by-hop forwarding strategy optimized for the fault free case. Second, they do not require information associated with network faults included in the packet header. Third, they do not form forwarding loops, even under multiple failures in the network. Finally, they are compatible with standard link state routing protocols. However, ECMP and LFA give very poor fault coverage; in most cases fewer than 50% of primary next-hops are protected when using typical link weight settings. This paper presents a new routing method that combines the concept of permutations with interface based routing. Our method results in a routing strategy that strictly adheres to the four stated design properties. Through experiments we show that we protect more than 97% of the primary next-hops for all tested ISP networks.
Afilliation | Communication Systems |
Project(s) | No Simula project |
Publication Type | Technical reports |
Year of Publication | 2012 |
Number | 2012-18 |
Publisher | Simula Research Laboratory |
Public outreach
Kan Markedet Gi Oss Robuste Telenett?
2012.Status: Published
Kan Markedet Gi Oss Robuste Telenett?
Afilliation | , Communication Systems |
Publication Type | Public outreach |
Year of Publication | 2012 |
Date Published | February |
Proceedings, refereed
Enhancing Shortest Path Routing for Resilience and Load Balancing
In Proceedings, International Conference on Communications 2011. IEEE, 2011.Status: Published
Enhancing Shortest Path Routing for Resilience and Load Balancing
This paper develops a new resilient multipath routing technique, referred to as SPT-DAG, that has the following characteristics: (1) provides multipath routing over directed acyclic graphs (DAG); (2) the shortest path tree is guaranteed to be part of the DAG; and (3) provides guaranteed recovery from single link failures. We develop a polynomial time algorithm to compute the SPT-DAG and a routing protocol to forward packets over the SPT-DAG using one overhead bit in the packet. We consider different load-balancing approaches for forwarding a packet when the packet has not encountered a failure. Through extensive flow-based simulations, we show that the SPT-DAG performs significantly better than those approaches that exclusively target load balancing or resiliency.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2011 |
Conference Name | Proceedings, International Conference on Communications 2011 |
Date Published | June |
Publisher | IEEE |
ISBN Number | xx |
On Update Rate-Limiting in BGP
In IEEE International Conference on Communications ICC 2011. IEEE, 2011.Status: Published
On Update Rate-Limiting in BGP
In order to reduce the number of BGP updates that routers need to process, it is common to rate-limit such updates using a timer that specifies the minimum time between two consecutive updates for a given destination prefix. Rate-limiting plays an important role in determining the number of routing updates that are generated after a routing event, and the time it takes before the network converges to a new stable state. Still, there are few guidelines for how rate-limiting timers should be configured in order to achieve the desired convergence properties. This work takes a first step in this direction, by exploring how different rate-limiting implementations and configurations affect the resulting churn level in a live BGP session. Measurements are performed on multiple parallel BGP sessions to a stub AS, configured with and without rate-limiting timers. We find that the daily rate of updates is reduced by two thirds when configuring the timer to the default value recommended by BGP standards. We further investigate different rate-limiting implementations and configurations using the measured BGP update patterns on emulated BGP sessions, and find that increasing the rate-limiting timer gives a logarithmic decrease in churn. Finally, using BGP update traces from RouteViews, we present the first empirical model that quantifies the impact of rate-limiting in terms of churn reduction given the observed arrival pattern of BGP updates.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2011 |
Conference Name | IEEE International Conference on Communications ICC 2011 |
Pagination | 1-6 |
Date Published | June |
Publisher | IEEE |
ISBN Number | 978-1-61284-232-5 |
DOI | 10.1109/icc.2011.5962884 |
SIMROT: a Scalable Inter-Domain Routing Toolbox
In SIGMETRICS Perform. Eval. Rev.. Vol. 39. ACM, 2011.Status: Published
SIMROT: a Scalable Inter-Domain Routing Toolbox
BGP plays a crucial role in the global communications in-frastructure, and there is a strong need for tools that can be used for analyzing its performance under different scenarios. The size and complexity of the inter-domain routing system often makes simulation the only viable method for such studies. This work addresses the lack of a comprehensive toolbox to simulate BGP. It proposes a flexible topology generator that produces AS-level graphs which are annotated with business relationships. The second component of the toolbox is a light-weight BGP simulator that is capable of capturing routing dynamics, while scaling to network sizes of thousands of nodes. We employ our frame- work to investigate a set of what-if questions concerning the impact of different topology parameters on BGP dynamics. This investigation shows how our proposed framework can help in gaining important insights on inter-domain routing dynamics.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2011 |
Conference Name | SIGMETRICS Perform. Eval. Rev. |
Volume | 39 |
Pagination | 4-13 |
Date Published | September |
Publisher | ACM |
ISBN Number | 0163-5999 |
DOI | 10.1145/2034832.20348 |
Proceedings, refereed
BGP Churn Evolution: a Perspective From the Core.
In 2010 Proceedings IEEE INFOCOM. IEEE, 2010.Status: Published
BGP Churn Evolution: a Perspective From the Core.
The scalability limitations of BGP have been a major concern in the networking community lately. An important issue in this respect is the rate of routing updates (churn) that BGP routers must process. This paper presents an analysis of the evolution of churn in four networks in the backbone of the Internet over the last six years, using update traces from the Routeviews project. The churn rate varies widely over time and between networks, and cannot be understood through ``black-box'' statistical analysis. Instead we take a different approach with a focus on investigating the underlying reasons for BGP churn evolution. Through our analysis we are able to identify and isolate the main reasons behind many of the anomalies in the churn time series. We find that duplicate announcements is a major churn contributor, and responsible for most large spikes in the churn time series. Other intense periods of churn are caused by misconfigurations or other special events in or close to the monitored AS, and hence limiting these is an important mean to limit churn. We then analyze the remaining ``baseline'' churn, and find that it is increasing with a rate much slower than the increase in the routing table size.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2010 |
Conference Name | 2010 Proceedings IEEE INFOCOM |
Publisher | IEEE |
ISBN Number | 978-1-4244-5838-7 |
Journal Article
Fast Recovery From Dual-Link Or Single-Node Failures in IP Networks Using Tunneling
IEEE/ACM Transactions on Networking 18 (2010): 1988-1999.Status: Published
Fast Recovery From Dual-Link Or Single-Node Failures in IP Networks Using Tunneling
This paper develops novel mechanisms for recovering from failures in IP networks with proactive backup path calculations and IP tunneling. The primary scheme provides resiliency against up to two link failures in a packet path in the network. The highlight of the developed routing approach is that a node re-routes a packet around the failed link without the knowledge of the second link failure. The proposed technique requires three protection addresses for every node, in addition to the normal address. Associated with every protection address of a node is a protection graph. Each link connected to the node is removed in at least one of the protection graphs and every protection graph is guaranteed to be two-edge connected. The network recovers from the first failure by tunneling the packet to the next-hop node using one of the protection addresses of the next-hop node; and the packet is routed over the protection graph corresponding to that protection address. We prove that it is sufficient to provide up to three protection addresses per node to tolerate any arbitrary two link failures in a three-edge connected graph. An extension to the basic scheme provides recovery from single node failures in the network. It involves identification of the failed node in the packet path and then routing the packet to the destination along an alternate path not containing the failed node. The effectiveness of the proposed techniques were evaluated by simulating the developed algorithms over several network topologies.
Afilliation | , Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2010 |
Journal | IEEE/ACM Transactions on Networking |
Volume | 18 |
Number | 6 |
Pagination | 1988-1999 |
Date Published | December |
DOI | 10.1109/TNET.2010.2055887 |
Loop-Free Alternates and Not-Via Addresses: a Proper Combination for IP Fast Reroute?
Computer Networks 54 (2010): 1300-1315.Status: Published
Loop-Free Alternates and Not-Via Addresses: a Proper Combination for IP Fast Reroute?
The IETF currently discusses fast reroute mechanisms for IP networks (IP FRR). IP FRR accelerates the recovery in case of network element failures and avoids micro-loops during re-convergence. Several mechanisms are proposed. Loop-free alternates (LFAs) are simple but cannot cover all single link and node failures. Not-via addresses can protect against these failures but are more complex, in particular, they use tunneling techniques to deviate backup traffic. In the IETF it has been proposed to combine both mechanisms to merge their advantages: simplicity and full failure coverage. This work analyzes LFAs and classifies them according to their abilities. We qualitatively compare LFAs and not-via addresses and develop a concept for their combined application to achieve 100% single failure coverage, while using simple LFAs wherever possible. The applicability of existing LFAs depends on the resilience requirements of the network. We study the backup path length and the link utilization for both IP FRR methods and quantify the decapsulation load and the increase of the routing table size caused by not-via addresses. We conclude that the combined usage of both methods has no advantage compared to the application of not-via addresses only.
Afilliation | , Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2010 |
Journal | Computer Networks |
Volume | 54 |
Number | 8 |
Pagination | 1300 - 1315 |
Date Published | June |
On the Scalability of BGP: the Role of Topology Growth
IEEE Journal on Selected Areas in Communications 28 (2010): 1250-1261.Status: Published
On the Scalability of BGP: the Role of Topology Growth
The scalability of BGP routing is a major concern for the Internet community. Scalability is an issue in two different aspects: increasing routing table size, and increasing rate of BGP updates. In this paper, we focus on the latter. Our objective is to characterize the churn increase experienced by ASes in different levels of the Internet hierarchy as the network grows. We look at several ``what-if'' growth scenarios that are either plausible directions in the evolution of the Internet or educational corner cases, and investigate their scalability implications and interaction with different failure types. Our findings explain the dramatically different impact of multihoming and peering on BGP scalability, highlight negative and positive effects of multihoming on churn and reachability, and identify which topological growth scenarios will lead to faster churn increase for different failure types.
Afilliation | , Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2010 |
Journal | IEEE Journal on Selected Areas in Communications |
Volume | 28 |
Number | 8 |
Pagination | 1250-1261 |
Date Published | October |
Notes | Special issue on Internet Routing Scalability. |
DOI | 10.1109/JSAC.2010.101003 |
Patent
Resilient Routing Systems and Methods
2010.Status: Published
Resilient Routing Systems and Methods
Afilliation | , Communication Systems |
Publication Type | Patent |
Year of Publication | 2010 |
Patent Number | US7724674B2 |
Resilient routing systems, computer software product and method
2010.Status: Published
Resilient routing systems, computer software product and method
Afilliation | , Communication Systems |
Publication Type | Patent |
Year of Publication | 2010 |
Patent Number | EP1821472B1 |
Proceedings, refereed
Analysis of Peer Selection Algorithms in Cross-Layer P2P Architectures
In International Workshop on Advances in Peer-to-Peer Technology, IWAP2PT09. IEEE COMSOC, 2009.Status: Published
Analysis of Peer Selection Algorithms in Cross-Layer P2P Architectures
The large amount of peer-to-peer (P2P) traffic in today's Internet represents a great challenge for most Internet Service providers (ISPs). P2P traffic does not conform to traditional ISP traffic policies, and it makes it harder to perform traffic engineering in the network. It is especially the peer-selection mechanism of the P2P application that influences the traffic patterns and creates an imbalance for the ISP business. Some ISPs benefit from the P2P traffic, while others suffer. There are research efforts proposing cross-layer solutions where the P2P application uses the underlying routing information for the peer selection. These works put a lot of focus on improving the application performance, but take to a little extent into account how the ISPs are affected. In this paper we propose a framework to measure the effects of the peer-selection mechanism, not only on the P2P application performance, but also on the economy of different types of ISPs. We categorize all ISPs into three groups; core, transit and stub, depending on their position in the global Internet hierarchy. Using our proposed framework, we analyze the performance of different peer-selection algorithms.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2009 |
Conference Name | International Workshop on Advances in Peer-to-Peer Technology, IWAP2PT09 |
Date Published | December |
Publisher | IEEE COMSOC |
Fast Recovery From Dual Link Failures in IP Networks
In Proceedings INFOCOM 2009. IEEE, 2009.Status: Published
Fast Recovery From Dual Link Failures in IP Networks
This paper develops a novel mechanism for recovering from dual-link failures in IP networks. The highlight of the developed routing approach is that a node re-routes a packet around the next-hop failed link without the knowledge of the second link failure. The proposed technique requires three protection addresses for every node, in addition to the normal address. Associated with every protection address of a node is a protection graph, in which some of the links connected to the node are removed. Every protection graph is guaranteed to be two-edge connected, hence can recover from one failure. The network recovers from the first failure by tunneling with protection address; and the tunneled packet is routed over the corresponding protection graph. We prove that it is sufficient to provide up to three protection graphs per node to tolerate any arbitrary two link failures in a three-edge connected graph. We evaluate the effectiveness of the proposed technique over several network topologies.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2009 |
Conference Name | Proceedings INFOCOM 2009 |
Publisher | IEEE |
ISBN Number | xx |
Multipath Load-Adaptive Routing: Putting the Emphasis on Robustness and Simplicity
In Proceedings ICNP 2009. IEEE, 2009.Status: Published
Multipath Load-Adaptive Routing: Putting the Emphasis on Robustness and Simplicity
We propose a routing and load-balancing approach with the primary goal of being robust to sudden topological changes and significant traffic matrix variations. The proposed method load-balances traffic over several routes in an adaptive way based on its local view of the load in the network. The focus is on robustness and simplicity, rather than optimality, and so it does not rely on a given traffic matrix, nor it is tuned to a specific topology. Instead, we aim to achieve a satisfactory routing under a wide range of traffic and topology scenarios based on each node's independent operation. The scheme avoids the instability risks of previous load-responsive routing schemes, it does not load the control plane with congestion-related signaling, and it can be implemented on top of existing routing protocols. In this paper, we present the proposed scheme, discuss how it aims to meet the objectives of robustness and load-responsiveness, and evaluate its performance under diverse traffic loads and topological changes with flow-level simulations.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2009 |
Conference Name | Proceedings ICNP 2009 |
Publisher | IEEE |
ISBN Number | xx |
Talks, contributed
BGP Churn Evolution: a Perspective From the Core
In Poster, Trilogy Summer School, Louvain-la-Neuve, Belgium, 2009.Status: Published
BGP Churn Evolution: a Perspective From the Core
Afilliation | , Communication Systems |
Publication Type | Talks, contributed |
Year of Publication | 2009 |
Location of Talk | Poster, Trilogy Summer School, Louvain-la-Neuve, Belgium |
Journal Article
Multiple Routing Configurations for Fast IP Network Recovery
IEEE/ACM Transactions on Networking 17 (2009): 473-486.Status: Published
Multiple Routing Configurations for Fast IP Network Recovery
As the Internet takes an increasingly central role in our communications infrastructure, the slow convergence of routing protocols after a network failure becomes a growing problem. To assure fast recovery from link and node failures in IP networks, we present a new recovery scheme called Multiple Routing Configurations (MRC). Our proposed scheme guarantees recovery in all single failure scenarios, using a single mechanism to handle both link and node failures, and without knowing the root cause of the failure. MRC is strictly connectionless, and assumes only destination based hop-by-hop forwarding. MRC is based on keeping additional routing information in the routers, and allows packet forwarding to continue on an alternative output link immediately after the detection of a failure. It can be implemented with only minor changes to existing solutions. In this paper we present MRC, and analyze its performance with respect to scalability, backup path lengths, and load distribution after a failure. We also show how an estimate of the traffic demands in the network can be used to improve the distribution of the recovered traffic, and thus reduce the chances of congestion when MRC is used.
Afilliation | , Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2009 |
Journal | IEEE/ACM Transactions on Networking |
Volume | 17 |
Number | 2 |
Pagination | 473-486 |
Date Published | April |
DOI | 10.1109/TNET.2008.926507 |
Relaxed Multiple Routing Configurations: IP Fast Reroute for Single and Correlated Failures
IEEE Transactions on Network and Service Management 6, no. 1 (2009): 1-14.Status: Published
Relaxed Multiple Routing Configurations: IP Fast Reroute for Single and Correlated Failures
Multi-topology routing is an increasingly popular IP network management concept that allows transport of different traffic types over disjoint network paths. The concept is of particular interest for implementation of IP fast reroute (IP FRR). First, it can support guaranteed, instantaneous recovery from any single link or node failure as well as from many combined failures. Second, different failures result in routing over different network topologies, which gives better control of the traffic distribution in the networks after a failure. The authors have previously proposed an IP FRR scheme based on multi-topology routing called Multiple Routing Configurations (MRC). In this paper we present an enhanced IP FRR scheme which we call ``relaxed MRC'' (rMRC). rMRC simplifies the topology construction and increases the routing flexibility in each topology. This makes rMRC better suited for successful load distribution after failures and handling of correlated failures. According to our experimental evaluation, the number of backup topologies required to provide protection against the same failures is reduced in rMRC compared to MRC, hence reducing state in routers. In addition, the backup paths are shorter, and the link utilization is significantly better. The paper also presents how rMRC can provide recovery from multiple correlated failures without compromising much on the number of backup topologies required and the path lengths.
Afilliation | , Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2009 |
Journal | IEEE Transactions on Network and Service Management |
Volume | 6 |
Issue | 1 |
Number | 1 |
Pagination | 1-14 |
Date Published | March |
Publisher | IEEE |
DOI | 10.1109/TNSM.2009.090301 |
Book Chapter
Providing Resilience in Communications Networks
In Simula Research Laboratory - by thinking constantly about it, 163-188. Heidelberg: Springer, 2009.Status: Published
Providing Resilience in Communications Networks
The purpose of the Resilient Networks Project at Simula is to provide resilience in communications networks with cost-efficient approaches. In particular, we identify and solve challenges for both Internet and wireless networks. In the Internet context, we focus on scalable solutions for maintaining network operations during failures or other challenging scenarios. This includes providing fast recovery from component failures, increasing robustness to failures and traffic fluctuations by spreading traffic on multiple paths, and investigating the scalability limitations of the current interdomain routing protocol BGP. Wireless resilience is highly dependent on a specific kind of wireless system and it is closely related to Quality-of-Service (QoS) provisioning. For this, we have investigated the resilience in resource-constrained sensor networks and QoS in OFDM-based wireless networks. It has been shown that the proposed strategies are able to substantially enhance network throughput and increase service reliability. In this chapter, we give an overview of the recent activities in the project, and briefly discuss future plans. Further technical details can be found in our journal and conference papers.
Afilliation | , Communication Systems |
Publication Type | Book Chapter |
Year of Publication | 2009 |
Book Title | Simula Research Laboratory - by thinking constantly about it |
Chapter | 15 |
Pagination | 163-188 |
Publisher | Springer |
Place Published | Heidelberg |
ISBN Number | 978-3-642-01156-6 |
Technical reports
The evolution of BGP churn in core networks
Simula Research Laboratory, 2009.Status: Published
The evolution of BGP churn in core networks
Afilliation | Communication Systems |
Project(s) | No Simula project |
Publication Type | Technical reports |
Year of Publication | 2009 |
Publisher | Simula Research Laboratory |
Proceedings, refereed
On the Scalability of BGP: the Roles of Topology Growth and Update Rate-Limiting
In CoNext 2008. ACM, 2008.Status: Published
On the Scalability of BGP: the Roles of Topology Growth and Update Rate-Limiting
The scalability of BGP routing is a major concern for the Internet community. Scalability is an issue in two different aspects: increasing routing table size, and increasing rate of BGP updates. In this paper, we focus on the latter. Our objective is to characterize the churn increase experienced by ASes in different levels of the Internet hierarchy as the network grows. We look at several ``what-if'' growth scenarios that are either plausible directions in the evolution of the Internet or educational corner cases, and investigate their scalability implications. In addition, we examine the effect of the BGP update rate-limiting timer (MRAI), considering both major variations with which it has been deployed. Our findings explain the dramatically different impact of multihoming and peering on BGP scalability, identify which topological growth scenarios will lead to faster churn increase, and emphasize the importance of not rate-limiting explicit withdrawals (despite what RFC-4271 recently required).
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2008 |
Conference Name | CoNext 2008 |
Publisher | ACM |
ISBN Number | 00000000 |
Relaxed Multiple Routing Configurations for IP Fast Reroute
In IEEE/IFIP Network Operations and Management Symposium (NOMS'08). IEE, 2008.Status: Published
Relaxed Multiple Routing Configurations for IP Fast Reroute
Multi-topology routing is an increasingly popular IP network management concept that allows transport of different traffic types over disjoint network paths. The concept is of particular interest for implementation of IP fast reroute (IP FRR). First, it can support guaranteed, instantaneous recovery from any link or node failure. Second, different failures result in routing over different network topologies, which augments the parameter space for load distribution optimizations. Multiple Routing Configurations (MRC) is the state-of-the-art IP FRR scheme based on multi-topology routing today. In this paper we present a new, enhanced IP FRR scheme which we call “relaxed MRC” (rMRC). rMRC simplifies the topology construction and increases the routing flexibility in each topology. According to our experimental evaluation, rMRC has several benefits compared to MRC. The number of backup topologies required to provide protection against the same set of failures is reduced, hence reducing state in routers. In addition, the backup paths are shorter, and the link utilization is significantly better.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2008 |
Conference Name | IEEE/IFIP Network Operations and Management Symposium (NOMS'08) |
Date Published | April |
Publisher | IEE |
ISBN Number | 978-1-4244-2066-7 |
Journal Article
An Empirical Comparison of Generators for Self Similar Simulated Traffic
Performance Evaluation 64 (2007): 162-190.Status: Published
An Empirical Comparison of Generators for Self Similar Simulated Traffic
It is generally recognised that aggregated network traffic is self similar and that self similar traffic models should be used in simulation experiments when assessing the performance of a network. Many generators have been proposed to synthetically produce self similar simulation input; however most of them require the trace length to be known a priori. Four generators that allow continuous generation of self similar time series are evaluated in this work with respect to their ability to reproduce the desired level of self similarity. This extensive investigation uses ten times as many traces and twice the number of parameter values as previously reported. Three of the tested generators perform well but surprisingly the generator supplied with a widely used commercial network simulator is unusable. The reported results indicate that the generator based on multiplexing strictly alternating ON/OFF sources may perform better than generators based on chaotic maps, provided that more than 100 ON/OFF sources can be used. Three estimators for the degree of self similarity of a time series have been evaluated as part of the process, and the only acceptable is based on a Wavelet decomposition of the traffic trace.
Afilliation | , Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2007 |
Journal | Performance Evaluation |
Volume | 64 |
Number | 2 |
Pagination | 162-190 |
Date Published | February |
PhD Thesis
Fast Network Recovery
University of Oslo, 2007.Status: Published
Fast Network Recovery
The Internet is increasingly used to transport time-critical traffic. Applications like video conferencing, television, telephony and distributed games have strict requirements to the delay and availability offered by the underlying network. At the same time, connectivity failures caused by failures in network equipment is a part of everyday operation in large communication systems. The traditional recovery mechanisms used in IP networks are not designed with real-time applications in mind. The distributed nature of popular intradomain routing protocols allows them to eventually recover from any number of failures that leaves the network connected, but this is a time consuming process that can lead to unacceptable performance degradations for some applications. In this work, we argue that there is a need for fast recovery mechanisms that allow packet forwarding to continue over alternate paths immediately after a failure, before the routing protocol has converged on the altered topology. To give rapid response, such mechanisms should be \emph{proactive} in the sense that an alternate route is readily available when a failure is discovered, and \emph{local}, so that the recovery action can be effected by the node that discovers the failure. Further, care should be taken so that the shifting of recovered traffic to an alternate route does not lead to congestion and packet loss in other parts of the network. We present and investigate mechanisms that can respond quickly to failures or unexpected traffic shifts in the network. First, we evaluate the recovery strategy used in a network protocol called Resilient Packet Ring (RPR). The ring topology used in RPR allows the implementation of very fast protection mechanisms. We look at the performance of these mechanisms, and propose improvements that reduce packet loss and shorten the experienced disruption time after a link or node failure. Then, in the main part of this work, we focus on fast recovery in general mesh networks. We present Resilient Routing Layers (RRL) and Multiple Routing Configurations (MRC), which are methods for near-instantaneous recovery from component failures in packet networks. We discuss and evaluate our mechanisms with respect to state requirements and distribution of the recovered traffic. For MRC, we move on to present methods for reducing the chances of congestion after a recovery operation. We show that if we have knowledge about the traffic demands, we can use this information to create MRC recovery paths that avoid the most heavily used parts of the network. Finally, we show how the concepts used in RRL and MRC to give recovery from component failures also can be used to avoid congestion when there are sudden shifts in the traffic distribution. Our method is more flexible than traditional traffic engineering methods used in connectionless IP networks, since it does not involve changing link weights to respond to a changed traffic situation. Fast recovery mechanisms like those proposed in this work can help improve the stability and availability of IP networks. This is an important requirement for enabling new and existing real-time applications over general-purpose Internet infrastructure.
Afilliation | , Communication Systems |
Publication Type | PhD Thesis |
Year of Publication | 2007 |
Date Published | June |
Publisher | University of Oslo |
Thesis Type | phd |
Proceedings, refereed
How Can Multi-Topology Routing Be Used for Intradomain Traffic Engineering?
In ACM SIGCOMM Workshop on Internet Network Management 2007. ACM sigcomm, 2007.Status: Published
How Can Multi-Topology Routing Be Used for Intradomain Traffic Engineering?
The concept of Multi-Topology routing allows each router in a network to maintain several valid routes to each destination. This increases the possibilities to spread traffic towards a destination over multiple paths with connectionless routing protocols like OSPF or IS-IS. In this paper, we report early ideas on how this can be utilized as a Traffic Engineering tool. We look at both offline and online approaches, and argue that a Multi-Topology based solution has advantages over previous solutions in both paradigms.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2007 |
Conference Name | ACM SIGCOMM Workshop on Internet Network Management 2007 |
Date Published | August |
Publisher | ACM sigcomm |
ISBN Number | unknown |
Post-Failure Routing Performance With Multiple Routing Configurations
In IEEE INFOCOM 2007. IEEE, 2007.Status: Published
Post-Failure Routing Performance With Multiple Routing Configurations
The slow convergence of IGP routing protocols after a topology change has led to several proposals for proactive recovery schemes in IP networks. These proposals are limited to guaranteeing loop-free connectivity after a link or node failure, and do not take into account the resulting load distribution in the network. This can lead to congestion and packet drops. In this work, we show how a good load distribution can be achieved in pure IP networks immediately after a link failure, when Multiple Routing Configurations (MRC) is used as a fast recovery mechanism. This paper is the first attempt to improve the load balancing when a proactive recovery scheme is used. Unlike load balancing methods used with normal IP rerouting, our method does not compromise on the routing performance in the failure free case. Our method is evaluated using simulations on several real and synthetically generated network topologies. The evaluation shows that our method yields good routing performance, making it feasible to use MRC to handle transient network failures.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2007 |
Conference Name | IEEE INFOCOM 2007 |
Date Published | May |
Publisher | IEEE |
ISBN Number | 1-4244-1047-0 |
Technical reports
Robust Load Balancing Using Multi-Topology Routing
Simula, 2007.Status: Published
Robust Load Balancing Using Multi-Topology Routing
Current methods for traffic engineering with traditional link state routing protocols like OSPF and IS-IS are based on optimizing link weights to fit a given estimate of the traffic demands. These methods are not good at handling natural changes in the traffic over time. In this paper, we introduce new methods for IGP load balancing based on the upcoming standard for Multi-Topology routing. The main advantage of our approach is that it is far more robust to changes in the traffic demands. Our initial evaluations indicate that our method significantly reduces the chances of losing packets due to congestion.
Afilliation | Communication Systems |
Project(s) | No Simula project |
Publication Type | Technical reports |
Year of Publication | 2007 |
Number | 2007-03 |
Publisher | Simula |
Proceedings, refereed
Fast IP Network Recovery Using Multiple Routing Configurations
In INFOCOM 2006. Barcelona, Spain: IEEE, 2006.Status: Published
Fast IP Network Recovery Using Multiple Routing Configurations
As the Internet takes an increasingly central role in our communications infrastructure, the slow convergence of routing protocols after a network failure becomes a growing problem. To assure fast recovery from link and node failures in IP networks, we present a new recovery scheme called Multiple Routing Configurations (MRC). MRC is based on keeping additional routing information in the routers, and allows packet forwarding to continue on an alternative output link immediately after the detection of a failure. Our proposed scheme guarantees recovery in all single failure scenarios, using a single mechanism to handle both link and node failures, and without knowing the root cause of the failure. MRC is strictly connectionless, and assumes only destination based hop-by-hop forwarding. It can be implemented with only minor changes to existing solutions. In this paper we present MRC, and analyze its performance with respect to scalability, backup path lengths, and load distribution after a failure.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2006 |
Conference Name | INFOCOM 2006 |
Pagination | 23-29 |
Date Published | April |
Publisher | IEEE |
Place Published | Barcelona, Spain |
ISBN Number | 1-4244-0222-0 |
Technical reports
Routing Efficiency With Link Failures Using Multiple Routing Configurations
Simula Research Laboratory, 2006.Status: Published
Routing Efficiency With Link Failures Using Multiple Routing Configurations
The slow convergence of IGP routing protocols after a topology change has led to several proposals for proactive recovery schemes in IP networks. These proposals are limited to guaranteeing loop-free connectivity after a link or node failure, and do not take into account the resulting load distribution in the network. This can lead to congestion and packet drops. In this work, we show how a good load distribution can be achieved in pure IP networks immediately after a link failure, when Multiple Routing Configurations (MRC) is used as a fast recovery mechanism. This paper is the first attempt to improve the load balancing when a proactive recovery scheme is used. Unlike load balancing methods used with normal IP rerouting, our method does not compromise on the routing performance in the failure free case. Our method is evaluated using simulations on several real and synthetically generated network topologies. The evaluation shows that our method yields good routing performance, making it feasible to use MRC to handle transient network failures.
Afilliation | Communication Systems |
Project(s) | No Simula project |
Publication Type | Technical reports |
Year of Publication | 2006 |
Number | 02-2006 |
Date Published | August |
Publisher | Simula Research Laboratory |
Technical reports
A Comparison of Different Approaches for Calculating Resilient Routing Layers and Multiple Routing Configurations
Simula Research Laboratory, 2005.Status: Published
A Comparison of Different Approaches for Calculating Resilient Routing Layers and Multiple Routing Configurations
Fast proactive recovery has for years been a very import- ant research field due to increased reliability in the Internet for business critical and real-time communications. Resilient Routing Layers (RRL) and Multiple Routing Configurations (MRC) has been proposed as a new approach providing local and proactive recovery. RRL and MRC also provides a network manager with a simple set of sub-topologies as abstractions for the recovery routing. This paper will compare different methods for generating such layers and configurations along two para- meters, scalability and effects on routing of the recovered traffic.
Afilliation | Communication Systems |
Project(s) | No Simula project |
Publication Type | Technical reports |
Year of Publication | 2005 |
Number | 2005-15 |
Date Published | September |
Publisher | Simula Research Laboratory |
Congestion Domain Boundaries in Resilient Packet Rings
Simula Research Laboratory, 2005.Status: Published
Congestion Domain Boundaries in Resilient Packet Rings
In June 2004, the IEEE approved a new standard for Resilient Packet Rings (RPR). The standard is maintained in the 802 LAN/MAN Standards Committee, and is designated the standard number 802.17. In this paper, we analyze and discuss performance aspects of the Resilient Packet Ring fairness mechanism. We explain that, if the ring is not configured correctly, the fairness mechanism fails to stabilize at a fair division of bandwidth between the active nodes. We present a novel addition to the fairness algorithm, and show that with this modification, RPR reaches a stable state with more optimal parameter settings. We also show that our proposed modification gives shorter convergence time for the Resilient Packet Ring fairness algorithm.
Afilliation | Communication Systems |
Project(s) | No Simula project |
Publication Type | Technical reports |
Year of Publication | 2005 |
Number | 2005-03 |
Date Published | February 2005 |
Publisher | Simula Research Laboratory |
Proceedings, refereed
An Analytical Bound for Convergence of the Resilient Packet Ring Aggressive Mode Fairness Algorithm
In Proceedings of the 40th annual IEEE International Conference on Communications, Seoul, Korea, May 16-20. IEEE, 2005.Status: Published
An Analytical Bound for Convergence of the Resilient Packet Ring Aggressive Mode Fairness Algorithm
Resilient Packet Ring (RPR) is a new standard, designated IEEE standard number 802.17, for MAN and WAN dual ring topologies. RPR uses the buffer insertion principle as a basis for its medium access control protocol. In this paper, we analyze parts of the aggressive mode of the RPR fairness protocol. We look at a congested node, and utilize control systems theory to analyze the stability of the associated fairness algorithm. In particular, we discuss how the settings of the two important parameters ageCoef and lpCoef influence the stability of an RPR-network. At the end of the paper we present simulated scenarios in order to illustrate our results.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | Proceedings of the 40th annual IEEE International Conference on Communications, Seoul, Korea, May 16-20 |
Date Published | May |
Publisher | IEEE |
Notes | ISBN 0-7803-8938-7 |
Fast Recovery From Link Failures Using Resilient Routing Layers
In 10th IEEE Symposium on Computers and Communications (ISCC 2005). Cartagena, Spain, June 27-30: IEEE Communications Society, 2005.Status: Published
Fast Recovery From Link Failures Using Resilient Routing Layers
We present a novel scheme for network recovery, named Resilient Routing Layers (RRL). Our proposed scheme is based on calculating fully connected topology subsets, termed layers, which are used to forward traffic in case of a network failure. For the purpose of this work, the layers are created to protect against link failures only. RRL keeps pre-calculated backup routing information in the network stations. This allows local response to network failures, which gives recovery in the order of milliseconds. The main strengths of our approach are its flexibility, as it is independent of the network technology used, and its simplicity, as it offers the network operator a simple and coherent view of the resources available after a link failure. We also show that our scheme scales well for networks of several hundred nodes.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | 10th IEEE Symposium on Computers and Communications (ISCC 2005) |
Pagination | 554-560 |
Date Published | June |
Publisher | IEEE Communications Society |
Place Published | Cartagena, Spain, June 27-30 |
Notes | ISSN 1530-1346, ISBN 0-7695-2373-0 |
Fast, Effective and Stable IP Recovery Using Resilient Routing Layers
In The 19th International Teletraffic Congress (ITC19) Beijing, China. Beijing University of Posts and Telecommunications Press, 2005.Status: Published
Fast, Effective and Stable IP Recovery Using Resilient Routing Layers
Recovery at the IP layer is hampered by the slow convergence of IP rerouting. Recovery times in the range of seconds do not adhere to the requirements of many Internet applications today. To offer fast, pre-configured and loop-free IP recovery we have proposed a new method named Resilient Routing Layers (RRL). In this paper we demonstrate how RRL also can provide resource-effective recovery in IP networks. We compare the performance of RRL with what intuitively should be the most resource-effective method: Full global rerouting.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | The 19th International Teletraffic Congress (ITC19) Beijing, China |
Pagination | 1631-1640 |
Date Published | August |
Publisher | Beijing University of Posts and Telecommunications Press |
Notes | ISBN 7-5635-1141-5 |
Improvement of Resilient Packet Ring Fairness
In Proceedings of the 48th annual IEEE Global Telecommunications Conference (GLOBECOM 2005), St. Lous, Missouri, USA, November 28-December 2. IEEE, 2005.Status: Published
Improvement of Resilient Packet Ring Fairness
Resilient Packet Ring (RPR, IEEE std. 802.17- 2004) is a recent networking standard developed by the IEEE LAN/MAN working group. RPR is an insertion buffer, dual ring technology, utilizing a back pressure based fairness algorithm to distribute bandwidth when congestion occurs. In its attempt to control a set of nodes sending behavior over a congested link, the RPR fairness algorithm suffers from two severe performance deficiencies. The first concerns how the node closest to a congested link calculates a fair rate estimate, the second deficiency relates to the method used to distribute this fair rate estimate to nodes upstream from the congested node. In this paper, we analyze these deficiencies and propose improvements to resolve them.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | Proceedings of the 48th annual IEEE Global Telecommunications Conference (GLOBECOM 2005), St. Lous, Missouri, USA, November 28-December 2 |
Date Published | November |
Publisher | IEEE |
Notes | ISBN 0-7803-9414-3 |
Performance Evaluation and Improvement of Non-Stable Resilent Packet Ring Behavior
In Proceedings of the 4th International Conference on Networking (ICN'05), Reunion, France, April 17-21 2005. LNCS 3421. Springer-Verlag GmbH, 2005.Status: Published
Performance Evaluation and Improvement of Non-Stable Resilent Packet Ring Behavior
Resilient Packet Ring (RPR) is a new networking standard developed by the IEEE LAN/MAN working group. RPR is an insertion buffer, dual ring technology, utilizing a back pressure based fairness algorithm to distribute bandwidth when congestion occurs. In its attempt to distribute bandwidth fairly, the calculated fair rate in general oscillates and under some conditions the oscillations continue indefinitely even under stable load conditions. In this paper, we evaluate the performance of the RPR ring during oscillations. In particular, we analyze transient behavior and how the oscillations of the fairness algorithm influence the throughput, both on a per node basis and for the total throughput of the ring. For congestion-situations, we conclude that, in most cases, RPR allows for full link-utilization and fair bandwidth distribution of the congested link. A modification to the RPR fairness algorithm has previously been proposed by the authors. We compare the improved fairness algorithm to the original, and find that the modified algorithm, for all evaluated scenarios perform at least as well as the original. In some problem scenarios, we find that the modified algorithm performs significantly better than the original.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | Proceedings of the 4th International Conference on Networking (ICN'05), Reunion, France, April 17-21 2005 |
Pagination | 551-563 |
Date Published | April |
Publisher | Springer-Verlag GmbH |
Notes | ISSN 0302-9743, ISBN 3-540-25339-4 |
Protection of RPR Strict Order Traffic
In Proceedings 14th IEEE Workshop on Local and Metropolitan Area Networks. Chania, Crete September 18-21: IEEE, 2005.Status: Published
Protection of RPR Strict Order Traffic
Resilient Packet Ring (RPR, IEEE 802.17) is designed with a protection mechanism aiming at restoring traffic on the ring within 50 ms in case of a link or node failure. However, the total experienced disruption time often exceeds this if strict order delivery of packets is required, since a 40 ms (configurable from 10 ms to 100 ms) topology stabilisation timer is used to avoid packet reordering. In this article, we present three alternative ways to avoid packet reordering for strict order traffic in RPR networks. The three suggested methods are discussed analytically, and simulations are used to compare their performance. Our simulation results suggest that the new methods give up to 90% reduction in packet loss during a failure situation compared to the current RPR standard.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | Proceedings 14th IEEE Workshop on Local and Metropolitan Area Networks |
Date Published | September |
Publisher | IEEE |
Place Published | Chania, Crete September 18-21 |
Resilent Packet Ring Low Priority Traffic Latency
In Proceedings of the 2005 International Conference on Communications in Computing: CIC 2005, Los Angeles CA, USA, February 2-4. CSREA Press, 2005.Status: Published
Resilent Packet Ring Low Priority Traffic Latency
Resilient Packet Ring (RPR - IEEE 802.17) is an insertion buffer, dual ring technology, utilizing a back pressure based fairness algorithm to distribute bandwidth when congestion occurs. The fairness algorithm may oscillate and under some conditions the oscillations continue indefinitely even under stable load conditions. In this paper, we evaluate the latency experienced by packets sent during such oscillations. We analyze transient behavior and how the oscillations of the fairness algorithm influence the jitter caused by unfair access to the ring, as well as jitter caused by the insertion buffers around the ring. We conclude that, in most cases, latency and jitter are within acceptable bounds. A modification to the RPR fairness algorithm has previously been proposed by the authors, but its implications on latency has never before been demonstrated. We compare the improved fairness algorithm to the original, and find that the modified algorithm, for all evaluated scenarios, perform at least as well as the original with respect to latency and jitter. In some problem scenarios, we find that the modified algorithm performs significantly better than the original.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | Proceedings of the 2005 International Conference on Communications in Computing: CIC 2005, Los Angeles CA, USA, February 2-4 |
Date Published | June |
Publisher | CSREA Press |
Notes | ISBN-1-932415-48-3 |
Resilient Routing Layers and P-Cycles: Tradeoffs in Network Fault Tolerance
In Proceedings 2005 Workshop on High Performance Switching and Routing, Hong Kong May 12-14. IEEE, 2005.Status: Published
Resilient Routing Layers and P-Cycles: Tradeoffs in Network Fault Tolerance
We compare p-cycles and the recently introduced Resilient Routing Layers as candidate schemes for network-level fault protection. Using computational routing trials we show that RRL has shorter backup path lengths and more successful double-link fault protection. On the other hand, p-cycles may require less forwarding state. Several tradeoffs of interest for network designers are described.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | Proceedings 2005 Workshop on High Performance Switching and Routing, Hong Kong May 12-14 |
Publisher | IEEE |
Notes | ISBN 0-7803-8924-7 |
Resilient Routing Layers for Network Disaster Planning
In Networking - ICN 2005: 4th International Conference on Networking, Reunion April 17-21. Lecture Notes in Computer Science, Volume 3421 / 2005. Springer-Verlag GmbH, 2005.Status: Published
Resilient Routing Layers for Network Disaster Planning
Most research on network recovery has been centered around two common assumptions regarding failure characteristics: Failures do not occur simultaneously and failures do mostly strike links. Even this may be the characteristics of everyday failures, we argue that disasters like earthquakes, power outages and terrorist attacks impose other failure characteristics. In this paper we demonstrate how our method, called Resilient Routing Layers, can be used as a tool for recovery from failures adhering to such disaster characteristics.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | Networking - ICN 2005: 4th International Conference on Networking, Reunion April 17-21 |
Pagination | 1097-1105 |
Date Published | March |
Publisher | Springer-Verlag GmbH |
Notes | ISSN 0302-9743, ISBN 3-540-25339-4, |
Resilient Routing Layers for Recovery in Packet Networks
In International Conference on Dependable Systems and Networks (DSN 2005) Yokohama, Japan, June 28-July 1. IEEE Computer Society, 2005.Status: Published
Resilient Routing Layers for Recovery in Packet Networks
The existing methods for network recovery are often complex and seldom used by network administrators. In this paper we present a novel approach for global and local recovery named Resilient Routing Layers (RRL). The method is supported by algorithms, but also simple enough for a network administrator to implement by hand for reasonably sized networks. The idea in our approach is that for each node in the network there is a topology subset called a “safe layer”, which can handle any traffc affected by a fault in the node itself, or any of its links. By analysis using different network topologies, we demonstrate that our approach performs well compared to other comparable methods. Particularly, we demonstrate RRLs performance for backup-path lengths and state information overhead that are assumed to be the weakest parameters for our method. We discuss implementation issues of RRL, and demonstrate its applicability to MPLS networks.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2005 |
Conference Name | International Conference on Dependable Systems and Networks (DSN 2005) Yokohama, Japan, June 28-July 1 |
Date Published | June |
Publisher | IEEE Computer Society |
Notes | ISBN 0-7695-2282-3 |
Proceedings, non-refereed
Resilient Routing Layers: an Overview of Technology and Applications
In EURO NGI Workshop on Traffic Engineering, Protection and Restoration, Rome April 18-20. EuroNGI, 2005.Status: Published
Resilient Routing Layers: an Overview of Technology and Applications
A thorough study of the network recovery methods available today reveals that there still exist a great potential for improvements. Most methods are optimized for handling single link failures, thus providing inadequate protection for node failures. Methods are often too complex to be adopted by network administrators in practice. Recovery in connectionless IP networks is still hampered by inappropriate delayed recovery due to slow convergence of IP rerouting. The authors have recently proposed Resilient Routing Layers (RRL) as an answer to some of the deficiencies observed from current methods. In this paper we will describe main features of RRL, present some recent research results and sketch our plans for future work.
Afilliation | Communication Systems, Communication Systems |
Publication Type | Proceedings, non-refereed |
Year of Publication | 2005 |
Conference Name | EURO NGI Workshop on Traffic Engineering, Protection and Restoration, Rome April 18-20 |
Date Published | April |
Publisher | EuroNGI |
Proceedings, refereed
Analysis and Improved Performance of RPR Protection
In Proceedings of the 12th IEEE Conference On Networks (ICON'04). Singapore: IEEE Computer Society Press, 2004.Status: Published
Analysis and Improved Performance of RPR Protection
Resilient Packet Ring (RPR, IEEE 802.17) is designed with a protection mechanism aiming at restoring traffic on the ring within 50 ms in case of a link or station failure. In this article, we evaluate RPR protection with respect to service disruption, packet reordering and packet loss. Different error scenarios are simulated, with both steering and wrapping protection. Unfortunately, the 50 ms restoration time guarantee can not always be met if in order delivery of packets is required, since RPR uses a quite long (default 40 ms) topology stabilisation period to avoid packet reordering. We suggest a novel protection mechanism, that does not have to wait for the new topology to be stable, and that gives sub 50 ms restoration for all traffic. We also show that for in order delivery of packets, our new mechanisms discards a very low number of packets compared to the mechanism of the RPR standard.
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2004 |
Conference Name | Proceedings of the 12th IEEE Conference On Networks (ICON'04) |
Pagination | 119-124 |
Date Published | November 16-19 |
Publisher | IEEE Computer Society Press |
Place Published | Singapore |
Performance Evaluation of an Enhanced Bridging Algorithm in RPR Networks
In Proceedings 3rd International Conference on Networking (ICN'04). Guadeloupe, French Caribbean: IEEE Computer Society Press, 2004.Status: Published
Performance Evaluation of an Enhanced Bridging Algorithm in RPR Networks
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2004 |
Conference Name | Proceedings 3rd International Conference on Networking (ICN'04) |
Pagination | 760-767 |
Date Published | February 29 - March 4 |
Publisher | IEEE Computer Society Press |
Place Published | Guadeloupe, French Caribbean |
The Vine Project: Towards Predictable Communication in Heterogeneous Networks
In Proceedings of the 3rd International Conference on Networking (ICN'04). Guadeloupe, French Caribbean: IEEE Computer Society Press, 2004.Status: Published
The Vine Project: Towards Predictable Communication in Heterogeneous Networks
Afilliation | , Communication Systems |
Publication Type | Proceedings, refereed |
Year of Publication | 2004 |
Conference Name | Proceedings of the 3rd International Conference on Networking (ICN'04) |
Pagination | 830-837 |
Date Published | February 29 - March 4 |
Publisher | IEEE Computer Society Press |
Place Published | Guadeloupe, French Caribbean |