@inproceedings {43297,
	title = {Evolved Cold-Potato routing experiences},
	journal = {The 31st International Conference on Software, Telecommunications and Computer Networks (SoftCOM 2023) },
	year = {2023},
	publisher = { IEEE},
	address = {Split, Croatia},
	abstract = {This paper presents a system designed to enhance Quality of Service (QoS) for a global video conferencing service. By a combination of off-the-shelf equipment and open-source software, the proposed system establishes a global service net- work with efficient cold-potato internal routing techniques.Through 15 years of operational experience, we have developed egress selection heuristics to minimize latency and loss in real- time, end-to-end services. The use of legacy routers and switches guarantees stability and security, while the implementation of specially adapted Route Reflector software provides flexibility.This study highlights the notable enhancements achieved in terms of accurate egress routing placement, latency reduction, and a significant decrease in customer support cases. By sharing our experiences, we aim to contribute valuable insights to the field of network optimization for real-time services.},
	keywords = {BGP, GeoIP, Routing},
	author = {Jan Marius {Evang} and Cicic, Tarik}
}
@techreport {43215,
	title = {Norske mobilnett i 2022},
	journal = {Tilstandsrapport fra Simula Metropolitan Center for Digital Engineering, Center for Resilient Networks and Applications},
	year = {2023},
	note = {},
	month = {05/2023},
	publisher = {Simula},
	address = {Oslo, Norway},
	abstract = {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 {\r a}rlig rapport om tilstanden i norske mobilnett. {\r A}rets rapport er den tiende i rekken.},
	keywords = {Mobile networks, Performance, Stability},
	isbn = {978-82-92593-38-7},
	url = {https://www.simulamet.no/sites/default/files/norske_mobilnett2022.pdf},
	author = {Cicic, Tarik and Kvalbein, Amund and Anas Saeed {Al-Selwi} and Foivos Ioannis {Michelinakis} and Dreibholz, Thomas}
}
@article {Simula.simula.2750,
	title = {Media Network As a Service},
	journal = {IEEE Communications Magazine},
	volume = {52},
	year = {2014},
	pages = {153-159},
	publisher = {IEEE},
	abstract = {Videoconferencing industry is undergoing the most substantial change in a decade. Demand for advanced collaboration functionality and highest quality of media presentation is meeting the requirement for Internet-based \&ldquo;over the top\&rdquo; communication, allowing unlimited communication between the organizations and individuals. We claim that these two contradictory requirements are best conciliated through deployment of a cloud service with elements of Network and Infrastructure as a Service (NaaS and IaaS) required to support global video- conferencing. The operational architecture we present enjoys full benefits of the cloud networking model, including elastic scaling, on-demand resource availability, and no-capex service model. The videoconferencing infrastructure requirements on the application level, and the quality requirements on the network level, are addressed in the single platform, opening for new optimization possibilities. We describe the network-level wide- area routing and service discovery mechanisms we have deployed to improve videoconferencing user experience through reduction of communication delay and packet loss. We further describe the service economy model, discussing the key trade-offs relevant for network cloud operations.},
	doi = {10.1109/MCOM.2014.6871683},
	author = {Cicic, Tarik and Elmokashfi, Ahmed}
}
@inproceedings {Simula.simula.2106,
	title = {Geography Matters: Building an Efficient Transport Network for a Better Video Conferencing Experience},
	journal = {CoNEXT},
	year = {2013},
	month = {December},
	pages = {369-380},
	publisher = {ACM},
	type = {Conference},
	abstract = {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 {\textquotedblleft}cold potato{\textquotedblright} 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.},
	keywords = {Conference},
	isbn = {978-1-4503-2101-3},
	author = {Elmokashfi, Ahmed and Myakotnykh, Eugene and Jan Marius {Evang} and Kvalbein, Amund and Cicic, Tarik},
	editor = {Papagiannaki, Dina and Misra, Vishal}
}
@inproceedings {Simula.simula.279,
	title = {On Update Rate-Limiting in BGP},
	journal = {IEEE International Conference on Communications ICC 2011},
	year = {2011},
	month = {June},
	pages = {1-6},
	publisher = {IEEE},
	type = {Conference},
	abstract = {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.},
	isbn = {978-1-61284-232-5},
	doi = {10.1109/icc.2011.5962884},
	author = {Elmokashfi, Ahmed and Kvalbein, Amund and Cicic, Tarik},
	editor = {IEEE, }
}
@article {Simula.ND.385,
	title = {Loop-Free Alternates and Not-Via Addresses: a Proper Combination for IP Fast Reroute?},
	journal = {Computer Networks},
	volume = {54},
	number = {8},
	year = {2010},
	month = {June},
	pages = {1300 - 1315},
	abstract = {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.},
	author = {Menth, Michael and Hartmann, Matthias and Martin, R{\"u}diger and Cicic, Tarik and Kvalbein, Amund}
}
@misc {Simula.simula.492,
	title = {Resilient Routing Systems and Methods},
	year = {2010},
	issn = {US7724674B2},
	author = {Lysne, Olav and Kvalbein, Amund and Audun Fosselie {Hansen} and Gjessing, Stein and Cicic, Tarik}
}
@misc {24156,
	title = {Resilient routing systems, computer software product and method},
	year = {2010},
	issn = {EP1821472B1},
	author = {Cicic, Tarik and Gjessing, Stein and Audun Fosselie {Hansen} and Kvalbein, Amund and Lysne, Olav}
}
@article {Simula.ND.4,
	title = {Multiple Routing Configurations for Fast IP Network Recovery},
	journal = {IEEE/ACM Transactions on Networking},
	volume = {17},
	number = {2},
	year = {2009},
	month = {April},
	pages = {473-486},
	abstract = {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.},
	doi = {10.1109/TNET.2008.926507},
	author = {Kvalbein, Amund and Audun Fosselie {Hansen} and Cicic, Tarik and Gjessing, Stein and Lysne, Olav}
}
@article {Simula.ND.351,
	title = {Relaxed Multiple Routing Configurations: IP Fast Reroute for Single and Correlated Failures},
	journal = {IEEE Transactions on Network and Service Management},
	volume = {6},
	number = {1},
	year = {2009},
	month = {March},
	pages = {1-14},
	publisher = {IEEE},
	abstract = {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 {\textquoteleft}{\textquoteleft}relaxed MRC\&$\#$39;\&$\#$39; (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.},
	doi = {10.1109/TNSM.2009.090301},
	author = {Cicic, Tarik and Audun Fosselie {Hansen} and Kvalbein, Amund and Hartmann, Matthias and Menth, Michael and Martin, R{\"u}diger and Gjessing, Stein and Lysne, Olav}
}
@inproceedings {Simula.ND.205,
	title = {Architecture and Performance of a Practical IP Fast Reroute Implementation},
	journal = {IEEE Global Communications Conference (GLOBECOM 2008)},
	year = {2008},
	month = {December},
	pages = {1-6},
	publisher = {IEEE},
	type = {Conference},
	abstract = {IP Fast Reroute (IP FRR) denominates a set of methods and technologies for proactive, local recovery in IP networks. It has received much attention recently, in the research community and the IETF. Several proposals for IP FRR have been published by independent research groups, and main properties and trade-offs are understood. However, only simulation-based and analytical evaluations are known to be performed so far. In this paper we present the architecture and evaluate performance of the first known practical implementation of IP FRR. The arcitecture features a modular approach consisting of an IP FRR framework and exchangeable backup path calculation modules. The performance evaluation is based on an implementation of Multiple Routing Configurations. The implementation provide throughput that closely matches the achieved performance during normal operation.},
	isbn = {978-1-4244-2324-8},
	author = {Ole Kristoffer {Apeland} and Cicic, Tarik},
	editor = {Richard W. {Miller}}
}
@inproceedings {Simula.ND.201,
	title = {IP Fast Reroute Using Relaxed MRC},
	journal = {SIGCOMM {\textquoteright}08: Proceedings of the ACM SIGCOMM 2008 conference on Data communication},
	year = {2008},
	month = {August},
	pages = {531},
	publisher = {ACM},
	type = {Conference},
	chapter = {Demo Session},
	abstract = {We demonstrate IP fast reroute using a recently proposed method called Relaxed Multiple Routing Configurations. While IP fast reroute has been researched intensively in recent years, no practical implementations are known to exist prior to the system we demonstrate. The goal of the demonstrator is to show the effect of network failures on real-time applications with and without IP fast reroute mechanisms deployed. For best illustration we use video transmission showing that IP fast reroute can elliminate frame freezing upon cable cut.},
	isbn = {978-1-60558-177-4},
	author = {Ole Kristoffer {Apeland} and Cicic, Tarik}
}
@inproceedings {Simula.ND.72,
	title = {Relaxed Multiple Routing Configurations for IP Fast Reroute},
	journal = {IEEE/IFIP Network Operations and Management Symposium (NOMS{\textquoteright}08)},
	year = {2008},
	month = {April},
	publisher = {IEE},
	type = {Conference},
	abstract = {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 {\textquotedblleft}relaxed MRC{\textquotedblright} (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.},
	isbn = {978-1-4244-2066-7},
	author = {Cicic, Tarik and Audun Fosselie {Hansen} and Kvalbein, Amund and Hartmann, Matthias and Martin, R"udiger and Menth, Michael},
	editor = {IEEE, }
}
@inproceedings {Simula.ND.7,
	title = {Fast Proactive Recovery From Concurrent Failures},
	journal = {IEEE International Conference on Communications (ICC 2007)},
	year = {2007},
	month = {June},
	publisher = {IEEE},
	type = {Conference},
	abstract = {Recovery of traffic in connectionless pure IP networks has traditionally been handled by a full re-convergence of the network state. This process operates in a time scale that is not compatible with new real time and highly dependable services. Recently, schemes for fast local and proactive recovery in connectionless IP networks have been proposed. All these schemes are designed to guarantee recovery of the failure of one component. As IP protocols are used to carry more highly dependable services and new wireless infrastructures are approaching, guaranteed failure coverage of more than one failure becomes necessary. In this paper we present and evaluate a scheme that guarantees to handle any two concurrent failures in a network. We are not aware of any other schemes that addresses such guarantees. We evaluate and compare it with other known recovery schemes, and we show how it gives substantially better recovery success rates than the schemes designed for one fault tolerance, also for more than two failures.},
	isbn = {1-4244-0353-7},
	author = {Audun Fosselie {Hansen} and Lysne, Olav and Cicic, Tarik and Gjessing, Stein},
	editor = {IEEE, }
}
@inproceedings {Simula.ND.209,
	title = {Muliple Routing Configurations Demonstrator: IP Fast Reroute in Practice},
	journal = {Middleware {\textquoteright}07: Proceedings of the 8th ACM/IFIP/USENIX international conference on Middleware},
	year = {2007},
	pages = {1-2},
	publisher = {ACM},
	type = {Conference},
	chapter = {Demo Session},
	abstract = {We demonstrate IP fast reroute using a recently proposed method called Multiple Routing Con{fi}gurations. The demonstrator comprises a small network of Linux routers, where the effect of network failures can be observed on real-time applications with and without IP fast reroute in effect.},
	isbn = {978-1-59593-935-7},
	author = {Cicic, Tarik and Ole Kristoffer {Apeland}}
}
@inproceedings {Kvalbein.2007.1,
	title = {Post-Failure Routing Performance With Multiple Routing Configurations},
	journal = {IEEE INFOCOM 2007},
	year = {2007},
	month = {May},
	publisher = {IEEE},
	type = {Conference},
	abstract = {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.},
	isbn = {1-4244-1047-0},
	author = {Kvalbein, Amund and Cicic, Tarik and Gjessing, Stein},
	editor = {Eytan Modiano Ge {Kesidis} and Srikant, R.}
}
@inproceedings {Simula.ND.34,
	title = {Redundant Trees for Fast IP Recovery},
	journal = {Broadnets 2007},
	year = {2007},
	month = {Sept.},
	publisher = {IEEE},
	type = {Conference},
	abstract = {Slow convergence of IP routing in case of network component failures represents a problem for emerging time-critical network applications. It has motivated work on IP fast reroute mechanisms that use local, proactive recovery in order to immediately provide alternative routes for the affected data packets. We present a new mechanism for IP fast recovery called IP Redundant Trees (IPRT). IPRT builds two redundant trees per network destination and pre-calculates backup next hops based on them. Combined with a smart forwarding scheme, IPRT provides proactive, local and loop-free recovery in connectionless IP networks. IPRT is simple and flexible, and requires a low increase of the routing state amount. We evaluate several key performance metrics in IPRT and other actual IP fast recovery proposals and argue that IPRT indeed has very attractive properties.},
	isbn = {0000000},
	author = {Cicic, Tarik and Audun Fosselie {Hansen} and Ole Kristoffer {Apeland}},
	editor = {IEEE, }
}
@inproceedings {Hansen.2006.1,
	title = {Alternative Schemes for Proactive IP Recovery},
	journal = {2nd Conference on Next Generation Internet Design and Engineering, Valencia, Spain April 3-5},
	year = {2006},
	month = {April},
	pages = {1-8},
	publisher = {IEEE},
	type = {1},
	abstract = {Recovery at the IP layer has originally been handled by the slow process of IP re-convergence. As the dependence on the Internet broadens and real time applications like VoIP become a common service of the Internet, fast proactive recovery becomes an important property of the communication protocols. There are currently two IETF initiatives for proactive recovery drawing considerable attention, IP Fast Reroute and Multi-Topology Routing using Multiple Routing Configurations. In this paper we evaluate and compare these approaches.},
	isbn = {0-7803-9455-0},
	author = {Audun Fosselie {Hansen} and Cicic, Tarik and Gjessing, Stein},
	editor = {Vicente Casares {Giner}}
}
@inproceedings {Kvalbein.2006.1,
	title = {Fast IP Network Recovery Using Multiple Routing Configurations},
	journal = {INFOCOM 2006},
	year = {2006},
	month = {April},
	pages = {23-29},
	publisher = {IEEE},
	type = {Conference},
	address = {Barcelona, Spain},
	abstract = {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.},
	isbn = {1-4244-0222-0},
	author = {Kvalbein, Amund and Audun Fosselie {Hansen} and Cicic, Tarik and Gjessing, Stein and Lysne, Olav},
	editor = {Azcorra, Arturo and Touch, Joe and Zhang, Zhili}
}
@inproceedings {Hansen.2006.2,
	title = {Profiles and Multi-Topology Routing in Highly Heterogeneous Ad Hoc Networks},
	journal = {INFOCOM 2006, Poster and Demo session, Barcelona, Spain April 23-29},
	year = {2006},
	month = {April},
	publisher = {IEEE},
	type = {1},
	abstract = {This paper points out multi-parameter heterogeneity as one of the main research challenges for future ad hoc network scenarios. Current research is often focusing on dealing with heterogeneity in terms of only one property, such as battery life or link capacity. Instead, we argue for a more holistic approach that can deal with heterogeneity in terms of a number of different parameters simultaneously. Profiled routing and multitopology routing are proposed as possible solutions.},
	author = {Audun Fosselie {Hansen} and Cicic, Tarik and Paal Einar {Engelstad}}
}
@techreport {25349,
	title = {Redundant Trees for Fast IP},
	year = {2006},
	publisher = {Simula Research Laboratory},
	author = {Cicic, Tarik and Audun Fosselie {Hansen}}
}
@techreport {Kvalbein.2006.2,
	title = {Routing Efficiency With Link Failures Using Multiple Routing Configurations},
	number = {02-2006},
	year = {2006},
	month = {August},
	publisher = {Simula Research Laboratory},
	abstract = {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.},
	author = {Kvalbein, Amund and Cicic, Tarik and Gjessing, Stein}
}
@inproceedings {Cicic.2006.1,
	title = {An Upper Bound on the State Requirements of Link-Fault Tolerant Multi-Topology Routing},
	journal = {International Conference on Communications (ICC)},
	year = {2006},
	month = {June},
	pages = {Electronic},
	publisher = {IEEE},
	type = {Conference},
	abstract = {Multi-topology routing is an increasingly popular concept in computer communications, and can be successfully applied to network fault tolerance. Multi-topology routing implies an increase in routing state requirements proportional to the number of logical topologies used. The network routing state is often subject to stringent system limits and should therefore be deterministically controllable. In this paper we show that the number of logical topologies needed to guarantee link-fault tolerant multi-topology routing has an upper bound determined by the network{\textquoteright}s largest minimal cycle. We provide a formal proof of validity of this bound in arbitrary biconnected networks. We also evaluate the quality of this bound, showing that it is reasonably strict.},
	isbn = {1-4244-0355-3},
	author = {Cicic, Tarik},
	editor = {Yenel, Lutfi}
}
@inproceedings {Cicic.2005.2,
	title = {Applicability of Resilient Routing Layers for K-Fault Network Recovery},
	journal = {Proceedings of International Conference on Networking (ICN), Reunion, France April 17-21},
	year = {2005},
	note = {ISSN 0302-9743, ISBN 3-540-25339-4,},
	pages = {173-183},
	publisher = {Springer-Verlag GmbH},
	type = {1},
	edition = {Vol. 3421},
	abstract = {Most networks experience several failures every day, and often multiple failures occur simultaneously. Still, most recovery mechanisms are not designed to handle multiple failures. We recently proposed a versatile recovery method called Resilient Routing Layers, and in this paper we analyze its suitability for handling multiple failures of network components. We propose a simple probabilistic algorithm for RRL layer creation, and evaluate its performance by comparing it with the Redundant Trees recovery mechanism. We show that not only does RRL provide better fault tolerance, but it also has qualitative advantages that make it very interesting in network systems design.},
	author = {Cicic, Tarik and Audun Fosselie {Hansen} and Gjessing, Stein and Lysne, Olav}
}
@techreport {Hansen.2005.6,
	title = {A Comparison of Different Approaches for Calculating Resilient Routing Layers and Multiple Routing Configurations},
	number = {2005-15},
	year = {2005},
	month = {September},
	publisher = {Simula Research Laboratory},
	abstract = {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.},
	author = {Audun Fosselie {Hansen} and Kvalbein, Amund and Cicic, Tarik and Gjessing, Stein and Lysne, Olav}
}
@inproceedings {Hansen.2005.3,
	title = {Fast, Effective and Stable IP Recovery Using Resilient Routing Layers},
	journal = {The 19th International Teletraffic Congress (ITC19) Beijing, China},
	year = {2005},
	note = {ISBN 7-5635-1141-5},
	month = {August},
	pages = {1631-1640},
	publisher = {Beijing University of Posts and Telecommunications Press},
	type = {1},
	abstract = {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.},
	author = {Audun Fosselie {Hansen} and Kvalbein, Amund and Cicic, Tarik and Gjessing, Stein and Lysne, Olav and Jensen, Terje and Olav Norvald {{\O}sterb{\o}}},
	editor = {Liang, Xiongjian and Xin, Zhanhong and V. B. {Iversen} and G. S. {Kuo}}
}
@inproceedings {Kvalbein.2005.1,
	title = {Fast Recovery From Link Failures Using Resilient Routing Layers},
	journal = {10th IEEE Symposium on Computers and Communications (ISCC 2005)},
	year = {2005},
	note = {ISSN 1530-1346, ISBN 0-7695-2373-0},
	month = {June},
	pages = {554-560},
	publisher = {IEEE Communications Society},
	type = {1},
	address = {Cartagena, Spain, June 27-30},
	abstract = {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.},
	author = {Kvalbein, Amund and Audun Fosselie {Hansen} and Cicic, Tarik and Gjessing, Stein and Lysne, Olav}
}
@inproceedings {Hansen.2005.4,
	title = {Resilient Routing Layers: an Overview of Technology and Applications},
	journal = {EURO NGI Workshop on Traffic Engineering, Protection and Restoration, Rome April 18-20},
	year = {2005},
	month = {April},
	publisher = {EuroNGI},
	type = {1},
	abstract = {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.},
	author = {Audun Fosselie {Hansen} and Kvalbein, Amund and Cicic, Tarik and Gjessing, Stein and Lysne, Olav}
}
@inproceedings {Cicic.2005.1,
	title = {Resilient Routing Layers and P-Cycles: Tradeoffs in Network Fault Tolerance},
	journal = {Proceedings 2005 Workshop on High Performance Switching and Routing, Hong Kong May 12-14},
	year = {2005},
	note = {ISBN 0-7803-8924-7},
	publisher = {IEEE},
	type = {1},
	abstract = {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.},
	author = {Cicic, Tarik and Kvalbein, Amund and Audun Fosselie {Hansen} and Gjessing, Stein}
}
@inproceedings {Hansen.2005.2,
	title = {Resilient Routing Layers for Network Disaster Planning},
	journal = {Networking - ICN 2005: 4th International Conference on Networking, Reunion April 17-21},
	year = {2005},
	note = {ISSN 0302-9743, ISBN 3-540-25339-4,},
	month = {March},
	pages = {1097-1105},
	publisher = {Springer-Verlag GmbH},
	type = {1},
	abstract = {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.},
	author = {Audun Fosselie {Hansen} and Kvalbein, Amund and Cicic, Tarik and Gjessing, Stein},
	editor = {Petre Dini Pasca {Lorenz}}
}
@inproceedings {Hansen.2005.1,
	title = {Resilient Routing Layers for Recovery in Packet Networks},
	journal = {International Conference on Dependable Systems and Networks (DSN 2005) Yokohama, Japan, June 28-July 1},
	year = {2005},
	note = {ISBN 0-7695-2282-3},
	month = {June},
	publisher = {IEEE Computer Society},
	type = {1},
	abstract = {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 {\textquotedblleft}safe layer{\textquotedblright}, 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.},
	author = {Audun Fosselie {Hansen} and Kvalbein, Amund and Cicic, Tarik and Gjessing, Stein and Lysne, Olav},
	editor = {Werner, Bob}
}
@techreport {Cicic.2005.3,
	title = {On Upper Bounds on the State Requirements of Fault-Tolerant Multi-Topology Routing},
	number = {2005-17},
	year = {2005},
	note = {Please note that after this report was published a counter-example has been found for a claim stated in Sec. 4.2. Please contact the author for details.},
	month = {12/2005},
	publisher = {Simula Research Laboratory},
	abstract = {Multi-topology routing is an increasingly popular concept in computer communications, and can be successfully applied to the network fault tolerance. Multi-topology routing implies an increase in routing state requirements proportional to the number of logical topologies used. The network routing state is often subject to stringent system limits and should therefore be deterministically controllable. In this paper we show that the minimal number of logical topologies needed to guarantee fault-tolerant multi-topology routing is related to the size of the largest minimal cycle (LMC) in the network. Link-fault tolerance and node-fault tolerance are discussed separately. For link-fault tolerant routing, the LMC size is the upper bound. For node-fault tolerant routing, the upper bound is the greatest of 6 and the LMC size of an arbitrary planar sub-topology. We provide formal proofs of validity of these bounds in arbitrary biconnected networks. We also evaluate the quality of these bounds, showing that they are reasonably strict.},
	author = {Cicic, Tarik}
}
@misc {Hansen.2004.1,
	title = {A Method for Recovery in Packet Networks},
	howpublished = {Norwegian Network Research Seminar 2004},
	year = {2004},
	note = {The same content as the Simula Technical Report 2004-13},
	month = {October},
	author = {Audun Fosselie {Hansen} and Cicic, Tarik and Gjessing, Stein and Lysne, Olav}
}
@article {ND.4.Cicic.2002,
	title = {Tree Recovery in PIM Sparse Mode},
	journal = {Telecommunication Systems},
	volume = {19},
	number = {3-4},
	year = {2002},
	month = {March - April},
	pages = {443-460},
	author = {Cicic, Tarik and Gjessing, Stein and Kure, {\O}ivind}
}
@inproceedings {ND.5.Cicic.2001.b,
	title = {An Improved PIM-SM Tree Recovery Algorithm},
	journal = {Proceedings IEEE Workshop in High Performance Switching and Routing},
	year = {2001},
	month = {June},
	publisher = {IEEE},
	type = {1},
	address = {Dallas, Texas},
	author = {Cicic, Tarik and Gjessing, Stein and Kure, {\O}ivind}
}
@inproceedings {ND.5.Cicic.2001.a,
	title = {Performace Evaluation of PIM-SM Recovery},
	journal = {Proceedings IEEE International Conference on Networking, ICN{\textasciiacute}01},
	year = {2001},
	month = {July},
	publisher = {Springer-Verlag},
	type = {1},
	address = {Colmar, France},
	author = {Cicic, Tarik and Gjessing, Stein and Kure, {\O}ivind}
}
@techreport {ND.7.Cicic.2001,
	title = {Topology Construction for Inter-Domain Network Protocol Simulations},
	number = {296},
	year = {2001},
	note = {ISBN 82-7368-246-3},
	month = {August},
	publisher = {Department of Informatics, University of Oslo},
	author = {Cicic, Tarik and Gjessing, Stein and Kure, {\O}ivind}
}
