Inführ, J., Stezenbach, D., Hartmann, M., Tutschku, K., Raidl, G.R.: Using Optimized Virtual Network Embedding for Network Dimensioning.IEEE Conference on Networked Systems (NetSys) 2013. , Stuttgart, Germany (2013).
Virtual Network Embedding will be one of the key concepts of the Future Internet. For an ISP it is important to know how many additional Virtual Networks (VNs) of a specific application (e.g. web, streaming, P2P, and VoIP) are mappable into the current resource substrate with a certain probability. In this work we calculate this probability with our embedding algorithm which enables us to consider side effects based on remapping of VNs (e.g. due to reduced link delay). Our results show that minimal extra resources can significantly increase embedding probability of additional VNs.
Tran-Gia, P., Hoßfeld, T., Hartmann, M., Hirth, M.: Crowdsourcing and its Impact on Future Internet Usage.it - Information Technology.55,139-145 (2013).
Crowdsourcing is an emerging service platform and business model in the Internet. In contrast to outsourcing where a job is performed by a designated contractor, with Crowdsourcing, jobs are outsourced to a large, anonymous crowd of workers, the so-called human cloud. The rise of Crowdsourcing and its seamless integration in current workflows may have a huge impact on the Internet and on society, and will be a guiding paradigm that can form the evolution of work in the years to come. In this article, we discuss applications and use cases of Crowdsourcing to demonstrate the impact on Internet usage. Novel measurement approaches are presented and the impact of Crowdsourcing on Internet traffic is evaluated by measuring the activity of a particular Crowdsourcing platform. New technical solutions are necessary for the operation of efficient, distributed Crowdsourcing platforms. Special attention is drawn to the integration of machine clouds and human crowds, and appropriate inter-cloud solutions. Finally, we discuss current research challenges from a scientific and from the platform provider’s point of view.
Klein, D., Tran-Gia, P., Hartmann, M.: Aktuelles Schlagwort: Big Data.Informatik-Spektrum.36,319-323 (2013).
Big Data ist neben Cloud Computing und Crowdsourcing eine der wichtigsten neuen Technologie-Treiber und wird daher im Aktuellen Schlagwort näher beleuchtet. Zu Beginn gehen wir auf die Definition von Big Data ein und erläutern die Unterschiede zu traditionellen Verfahren. Im Anschluss daran stellen wir zugrundeliegende Technologien vor und geben einen kurzen Überblick über wissenschaftliche Herausforderungen in diesem Bereich.
Hock, D., Hartmann, M., Gebert, S., Jarschel, M., Zinner, T., Tran-Gia, P.: Pareto-Optimal Resilient Controller Placement in SDN-based Core Networks.25th International Teletraffic Congress (ITC). , Shanghai, China (2013).
With the introduction of Software Defined Networking (SDN), the concept of an external and optionally centralized network control plane, i.e. controller, is drawing the attention of researchers and industry. A particularly important task in the SDN context is the placement of such external resources in the network. In this paper, we discuss important aspects of the controller placement problem with a focus on SDN-based core networks, including different types of resilience and failure tolerance. When several performance and resilience metrics are considered, there is usually no single best controller placement solution, but a trade-off between these metrics. We introduce our framework for resilient Pareto-based Optimal COntroller-placement (POCO) that provides the operator of a network with all Pareto-optimal placements. The ideas and mechanisms are illustrated using the Internet2 OS3E topology and further evaluated on more than 140 topologies of the Topology Zoo. In particular, our findings reveal that for most of the topologies more than 20% of all nodes need to be controllers to assure a continuous connection of all nodes to one of the controllers in any arbitrary double link or node failure scenario.
Menth, M., Hartmann, M., Klein, D.: Global Locator, Local Locator, and Identifier Split (GLI-Split).Future Internet.5,67-94 (2013).
The locator/identifier split is an approach for a new addressing and routing architecture to make routing in the core of the Internet more scalable. Based on this principle, we developed the GLI-Split framework, which separates the functionality of current IP addresses into a stable identifier and two independent locators, one for routing in the Internet core and one for edge networks. This makes routing in the Internet more stable and provides more flexibility for edge networks. GLI-Split can be incrementally deployed and it is backward-compatible with the IPv6 Internet. We describe its architecture, compare it to other approaches, present its benefits, and finally present a proof-of-concept implementation of GLI-Split.
Hoefling, M., Menth, M., Hartmann, M.: A Survey of Mapping Systems for Locator/Identifier Split Internet Routing.IEEE Communications Surveys & Tutorials.14,1842 - 1858 (2013).
The locator/identifier split is a core principle of many recently proposed routing architectures for a scalable future Internet. It splits the function of today’s IP addresses into two separate pieces. End-hosts are addressed using identifiers which are not globally routable while network attachment points have globally routable locators assigned. In most architectures, either the sending host or an intermediate node has to query a mapping system to obtain locators for identifiers. Such a mapping system must be fast, reliable, secure, and may be able to relay data packets. In this paper, we propose requirements and a general taxonomy for mapping systems and use it to provide a survey on recent proposals. We address general aspects of mapping systems and point out remaining research opportunities.
Hock, D., Hartmann, M., Menth, M., Pióro, M., Tomaszewski, A., Żukowski, C.: Comparison of IP-Based and Explicit Paths for One-to-One Fast Reroute in MPLS Networks.Telecommunication Systems (TS) Journal.52,947-958 (2013).
Primary and backup paths in MPLS fast reroute (FRR) may be established as shortest paths according to the administrative link costs of the IP control plane, or as explicitly calculated arbitrary paths. In both cases, the path layout can be optimized so that the maximum link utilization for a specific traffic matrix and for a set of considered failure scenarios is minimized. In this paper, we propose a linear program for the optimization of the path layout for explicitly calculated paths, which can either produce single paths and route entire traffic along those paths, or generate multiple paths and spread the traffic among those paths providing load balancing. We compare the resulting lowest maximum link utilization in both cases with the lowest maximum link utilization that can be obtained by optimizing unique IP-based paths. Our results quantify the gain in resource efficiency usage provided by optimized explicit multiple paths or explicit single paths as compared to optimized IP-based paths. Furthermore, we investigate if explicit path layouts cause an increased configuration effort compared to IP-based layouts and if yes, to what extend.
Hock, D., Hartmann, M., Schwartz, C., Menth, M.: ResiLyzer: Ein Werkzeug zur Analyse der Ausfallsicherheit in paketvermittelten Kommunikationsnetzen.PIK - Praxis der Informationsverarbeitung und Kommunikation.34,158-159 (2011).
Żukowski, C., Tomaszewski, A., Pióro, M., Hock, D., Hartmann, M., Menth, M.: Compact node-link formulations for the optimal single path MPLS Fast Reroute layout.Advances in Electronics and Telecommunications.2, (2011).
This paper discusses compact node-link formulations for MPLS fast reroute optimal single path layout. We propose mathematical formulations for MPLS fast reroute local protection mechanisms. In fact, we compare one-to-one (also called detour) local protection and many-to-one (also called facility backup) local protection mechanisms with respect to minimized maximum link utilization. The optimal results provided by the node-links are compared with the suboptimal results provided by algorithms based on non-compact linear programming (path generation) approach and IP-based approach.
Hock, D., Hartmann, M., Neubert, T., Menth, M.: Loop-Free Convergence using Ordered FIB Updates: Analysis and Routing Optimization.8th International Workshop on the Design of Reliable Communication Networks (DRCN). , Krakow, Poland (2011).
Żukowski, C., Tomaszewski, A., Pióro, M., Hock, D., Hartmann, M., Menth, M.: Compact node-link formulations for the optimal single path MPLS Fast Reroute layout.1st European Teletraffic Seminar (ETS). , Poznan, Poland (2011).
Hock, D., Hartmann, M., Schwartz, C., Menth, M.: ResiLyzer: Ein Werkzeug zur Analyse der Ausfallsicherheit in paketvermittelten Kommunikationsnetzen, (2011).
Menth, M., Hartmann, M., Hoefling, M.: FIRMS: A Mapping System for Future Internet Routing.IEEE Journal on Selected Areas in Communications (JSAC), Special Issue on Internet Routing Scalability.28,1326-1331 (2010).
The locator/identifier split is a design principle for new routing architectures that make Internet routing more scalable. To find the location of a host, it requires a mapping system that returns appropriate locators in response to map-requests for specific identifiers. In this paper, we propose FIRMS, a 'Future Internet Routing Mapping System'. It is fast, scalable, reliable, secure, and it is able to relay initial packets. We introduce its design, show how it deals with partial failures, explain its security concept, and evaluate its scalability.
Hock, D., Hartmann, M., Menth, M., Schwartz, C.: Optimizing Unique Shortest Paths for Resilient Routing and Fast Reroute in IP-Based Networks.IEEE/IFIP Network Operations and Management Symposium (NOMS). , Osaka, Japan (2010).
Intradomain routing in IP networks follows shortest paths according to administrative link costs. When several equalcost shortest paths exist, routers that use equal-cost multipath (ECMP) distribute the traffic over all of them. To produce singleshortest path (SSP) routing, a selection mechanism (tie-breaker) chooses just one of the equal-cost paths. Tie-breakers are poorly standardized and use information that may change over time, which makes SSP routing unpredictable. Therefore, link costs producing unique shortest paths (USP) are preferred. In this paper, we show that optimized SSP routing can lead to significantly higher link utilization than expected in case of non-deterministic tie-breakers. We investigate the impact of the allowed link cost range on the general availability of USP routing. We use a heuristic algorithm to generate link costs for USP routing and to minimize the maximum link utilization in networks with and without failures. Fast reroute (FRR) mechanisms can repair failures faster than conventional IP rerouting by pre-computing shortest backup paths around failed network elements. However, when multiple equal-cost paths exist, the backup path layout is unpredictable. We adapt our heuristic to optimize USP routing for IP-FRR using not-via addresses and MPLS-FRR with facility and oneto- one backup. Finally, we compare the performance of USP with various other routing schemes using realistic Rocketfuel topologies.
Klein, D., Hartmann, M., Höfling, M., Menth, M.: Improvements to LISP Mobile Node Including NAT Traversal, (2010).
Hartmann, M., Hock, D., Höfling, M., Neubert, T., Menth, M.: FIRMS - Demonstration of a Mapping System for Loc/ID Split Internet Routing in G-Lab, (2010).
Hartmann, M.: Neue Routing-Paradigmen für das zukünftige Internet., Datev Trendscout, Nürnberg (2010).
Menth, M., Hartmann, M., Martin, R., Cicic, T., Kvalbein, A.: Loop-Free Alternates and Not-Via Addresses: A Proper Combination for IP Fast Reroute?Computer Networks.54,1300-1315 (2010).
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.
Hock, D., Hartmann, M., Schwartz, C., Menth, M.: Effectiveness of Link Cost Optimization for IP Rerouting and IP Fast Reroute.15th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems and Dependability and Fault Tolerance (MMB & DFT 2010). , Essen, Germany (2010).
In this paper, we bring together resilience analysis and routing optimization for IP-based intra-domain networks. When link, node, or multiple failures occur, traffic is rerouted which increases the link load on backup paths and possibly causes congestion. Resilience analysis detects the risk of overload situations a priori based on a large set of most likely failure scenarios. To counteract, the routing can be optimized and configured that such bottlenecks are avoided at least for a smaller set of failure scenarios. In this paper, we demonstrate the effectiveness of this routing optimization in IP networks. We use resilience analysis with suitable aggregate views on relative link loads. Furthermore, we compare conventional IP rerouting with IP fast reroute (IP-FRR) and show that IP-FRR can also significantly profit from routing optimization. This paper reviews major parts of previous publications and presents a new method to visualize and compare the resilience of different routing schemes.
Hock, D., Menth, M., Hartmann, M., Schwartz, C., Stezenbach, D.: ResiLyzer: A Tool for Resilience Analysis in Packet-Switched Communication Networks.15th International GI/ITG Conference on Measurement, Modelling and Evaluation of Computing Systems and Dependability and Fault Tolerance (MMB & DFT 2010). , Essen, Germany (2010).
We present a tool for the analysis of fault-tolerance in packet-switched communication networks. Network elements like links or routers can fail or unexpected traffic surges may occur. They lead to service disruptions and degradations. Our tool quantifies these risks and presents a comprehensive digest of the results. We explain the core idea of the analysis and illustrate the tool.
Menth, M., Klein, D., Hartmann, M.: Improvements to LISP Mobile Node.22nd International Teletraffic Congress (ITC). , Amsterdam, The Netherlands (2010).
The Locator/Identifier Separation Protocol (LISP) is a new routing architecture for the Internet that separates local and global routing. It offers more flexibility to edge networks and has the potential to reduce the growths of the BGP routing tables. Recently, a concept for mobility in LISP (LISP Mobile Node, LISP-MN) was presented. We analyze LISP-MN and show that it needs double mapping lookups in all LISP gateways, leads to triangle routing under some conditions, and requires double encapsulation. We propose gradual improvements to LISP-MN that avoid these drawbacks under many conditions.
Pióro, M., Tomaszewski, A., Żukowski, C., Hock, D., Hartmann, M., Menth, M.: Optimized IP-Based vs. Explicit Paths for One-to-One Backup in MPLS Fast Reroute.14th International Telecommunications Network Strategy and Planning Symposium (NETWORKS 2010), Best Paper Award. , Warsaw, Poland (2010).
Primary and backup paths in MPLS fast reroute (FRR) may be established as shortest paths according to the administrative link costs of the IP control plane, or as explicitly calculated arbitrary paths. In both cases, the path layout can be optimized so that the maximum link utilization for a set of considered failure scenarios is minimized. In this paper, we propose a linear program for the optimization of the path layout for explicitly calculated paths, which can either produce single paths and route entire traffic along those paths, or generate multiple paths and spread the traffic among those paths providing load balancing. We compare the resulting lowest maximum link utilization in both cases with the lowest maximum link utilization that can be obtained by optimizing unique IP-based paths. Our results quantify the gain in resource efficiency usage provided by optimized explicit multiple paths or explicit single paths as compared to optimized IP-based paths.
Klein, D., Hartmann, M., Menth, M.: NAT Traversal for LISP Mobile Node.ACM CoNEXT workshop Re-Architecting the Internet (ReArch). , Philadelphia, PA, USA (2010).
The Locator/ID Separation Protocol (LISP) is currently being developed and standardized in the IETF aiming to solve the Internet's routing scaling problem. It separates global routing in the Internet from local routing in end-user networks (so-called LISP-domains). It also provides additional benefits like simplified multihoming or the avoidance of network renumbering. The basic LISP architecture does not support mobility. Recently, the mobility extension LISP Mobile Node (LISP-MN) was presented. It describes a mechanism that enables LISP mobile nodes to roam into LISP and non-LISP networks while being reachable under the same identifier address. Currently, LISP-MN does not support networks that use network address translation (NAT). In this paper, we present a NAT traversal mechanism for LISP mobile nodes and a slight adaptation which is also applicable to stationary LISP domains behind a NAT.
Menth, M., Klein, D., Hartmann, M.: Improvements to LISP Mobile Node, (2010).
Menth, M., Hartmann, M., Hoefling, M.: Mapping Systems for Loc/ID Split Internet Routing.University of Wuerzburg (2010).
Menth, M., Hartmann, M., Klein, D.: Global Locator, Local Locator, and Identifier Split (GLI-Split).University of Wuerzburg (2010).
Menth, M., Martin, R., Hartmann, M., Spörlein, U.: Efficiency of Routing and Resilience Mechanisms in Packet-Switched Communication Networks.European Transactions on Telecommunications.21,108-120 (2010).
In this work we compare the efficiency of various routing and resilience mechanisms. Their path layout determines the utilization of links in the network under normal operation and in failure scenarios. For the comparison, the performance measure is the maximum utilization rS of all links for a set of protected failures S. A routing mechanism is considered more efficient than another if it leads to a lower maximum link utilization rS. We consider standard and optimized versions of IP routing and rerouting, optimized routing using explicit paths and end-to-end protection switching, as well as standard and optimized versions of MPLS fast reroute. The results show that routing optimization reduces the maximum link utilization significantly both with and without failure protection. The optimization potential for resilient routing is limited by the applied mechanism and depends heavily on the network structure and the set of protected failure scenarios S.
Cicic, T., Fosselie Hansen, A., Kvalbein, A., Hartmann, M., Martin, R., Menth, M., Gjessing, S., Lysne, O.: Relaxed Multiple Routing Configurations: IP Fast Reroute for Single and Correlated Failures.IEEE Transactions on Network and Service Managment.6,1-14 (2009).
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). The authors have previously proposed an IP FRR scheme based on multi-topology routing called Multiple Routing Configurations (MRC). MRC supports guaranteed, instantaneous recovery from any single link or node failure in biconnected networks as well as from many combined failures, provided sufficient bandwidth on the surviving links. Furthermore, in MRC different failures result in routing over different network topologies, which gives a good control of the traffic distribution in the networks after a failure. In this paper we present two contributions. First we define an enhanced IP FRR scheme which we call 'relaxed MRC' (rMRC). Through experiments we demonstrate that rMRC is an improvement over MRC in all important aspects. Resource utilization in the presence of failures is significantly better, both in terms of paths lengths and in terms of load distribution between the links. The requirement to internal state in the routers is reduced as rMRC requires fewer backup topologies to provide the same degree of protection. In addition to this, the preprocessing needed to generate the backup topologies is simplified. The second contribution is an extension of rMRC that can provide fast reroute in the presence of multiple correlated failures. Our evaluations demonstrate only a small penalty in path lengths and in the number of backup topologies required.
Hartmann, M., Hock, D., Menth, M., Schwartz, C.: Objective Functions for Optimization of Resilient and Non-Resilient IP Routing.7th International Workshop on the Design of Reliable Communication Networks (DRCN). , Washington, D.C., USA (2009).
Intradomain routing in IP networks follows leastcost paths according to administrative link costs. Routing optimization modifies these values to minimize an objective function for a network with given link capacities and traffic matrix. An example for an objective function is the maximum utilization of all links under failure-free conditions or also after rerouting in case of network failures. Many papers have provided heuristic algorithms for routing optimization using different objective functions, but the investigation and comparison of various objective functions has not attracted much attention so far. In this work we present several objective functions for resilient IP routing. We also propose a new combined optimization approach which can simultaneously optimize different objective functions with almost no additional computation effort and describe new techniques to minimize overall computation time. The different objective functions and combinations thereof are then analyzed and compared experimentally.
Menth, M., Hartmann, M.: Threshold Configuration and Routing Optimization for PCN-Based Resilient Admission Control.Computer Networks.Volume 53, Issue 11, (2009).
Pre-congestion notification (PCN) in IP networks uses packet metering and marking within a PCN domain to notify its egress nodes whether link-specific admissible or supportable rate thresholds have been exceeded by high priority traffic. Based on this information simple admission control and flow termination is implemented. The latter is a new flow control function and useful in case of overload through high priority traffic which can occur in spite of admission control, e.g., when traffic is rerouted in failure cases. Resilient admission control admits only so much traffic that admitted traffic can be rerouted without causing congestion on backup paths in case of a likely failures, e.g., single link failures. We propose algorithms to configure the link-specific PCN rate thresholds such that resources are utilized efficiently and fairly by competing traffic aggregates while meeting resilience constraints. This is done for the single and dual marking PCN architecture whereby the single marking case is more demanding since it requires that the supportable rate is a fixed multiple of the admissible rate on all links within a single PCN domain. Furthermore, we derive objective functions to optimize the underlying routing system for both cases. Our performance results for various network types show that the dual marking PCN architecture leads to significantly better resource efficiency than the single marking PCN architecture.
Menth, M., Hartmann, M., Klein, D.: Global Locator, Local Locator, and Identifier Split (GLI-Split), (2009).
Menth, M., Hartmann, M., Höfling, M.: FIRMS: Future Internet Mapping System, (2009).
Cicic, T., Fosselie Hansen, A., Kvalbein, A., Hartmann, M., Martin, R., Menth, M.: Relaxed Multiple Routing Configurations for IP Fast Reroute.IEEE/IFIP Network Operations and Management Symposium. , Salvador, Bahia, Brazil (2008).
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.
Duelli, M., Hartmann, M., Menth, M., Hülsermann, R., Düser, M.: Performance Evaluation of IP over Cost-Optimized Optical Multilayer Networks with SRLGs.9. ITG-Fachtagung Photonische Netze. p. 21--29. , Leipzig, Germany (2008).
The design of optical transport and IP networks is investigated with respect to the effect on overall network perfor mance when the two aspects are combined in the same network architecture. The focus is on the identification of advantages in the joint design of IP and transport networks, as well as on the shortcomings and network bottlenecks which may result from sub-optimal design. The impact of different IP routing strategies (shortest path, equal-cost multipath) on the network utilization is quantified, and potential sources for overload in the IP domain are determined. Simulations were carried out to systematically assess technical metrics like link utilization and economic parameters such as cost for a 50-node transport network with line rates up to 40 Gbit/s. The impact of fiber cuts was taken into account, leading to multiple logical IP links to fail simultaneously, i.e. shared risk link groups (SRLGs), and triggering massive IP rerouting. Applying the results allows to identify bottlenecks in the design, and to devise mechanisms which allow cost-optimal network design of future IP and optical transport networks.
Zinner, T., Hartmann, M.: Transitionspfade zu IPv6., Datev Trendscout, Nürnberg (2008).
Menth, M., Hartmann, M., Tran-Gia, P., Klein, D.: Future Internet Routing: Motivation and Design Issues.it - Information Technology.50(6), (2008).
Pre-congestion notification (PCN) in IP networks uses packet metering and marking within a PCN domain to notify its egress nodes whether link-specific admissible or supportable rate thresholds have been exceeded by high priority traffic. Based on this information simple admission control and flow termination is implemented. The latter is a new flow control function and useful in case of overload through high priority traffic which can occur in spite of admission control, e.g., when traffic is rerouted in failure cases. Resilient admission control admits only so much traffic that admitted traffic can be rerouted without causing congestion on backup paths in case of a likely failures, e.g., single link failures. We propose algorithms to configure the link-specific PCN rate thresholds such that resources are utilized efficiently and fairly by competing traffic aggregates while meeting resilience constraints. This is done for the single and dual marking PCN architecture whereby the single marking case is more demanding since it requires that the supportable rate is a fixed multiple of the admissible rate on all links within a single PCN domain. Furthermore, we derive objective functions to optimize the underlying routing system for both cases. Our performance results for various network types show that the dual marking PCN architecture leads to significantly better resource efficiency than the single marking PCN architecture.
Menth, M., Hartmann, M., Martin, R.: Robust IP Link Costs for Multilayer Resilience.University of Wuerzburg (2007).
Menth, M., Martin, R., Hartmann, M., Spörlein, U.: Efficiency of Routing and Resilience Mechanisms in Packet-Switched Networks.University of Wuerzburg (2007).
Hartmann, M.: Performance Analysis and Optimization of IP Fast Reroute Mechanisms, (2007).
Martin, R., Menth, M., Hartmann, M., Cicic, T., Kvalbein, A.: The Effect of Combining Loop-Free Alternates and Not-Via Addresses in IP Fast Reroute.University of Wuerzburg (2007).
Menth, M., Hartmann, M., Martin, R.: Robust IP Link Costs for Multilayer Resilience.6th IFIP-TC6 Networking Conference (Networking). , Atlanta, GA, USA (2007).
In this work we optimize administrative link costs of IP networks in such a way that the maximum utilization of all links is as low as possible for a set of considered failure scenarios (e.g., all single link failures). To that aim, we present the new 'hill hopping' heuristic with three different variants and compare their computation times and the quality of their results. We adapt the objective function of the heuristic to make the link cost settings robust to single link failures, single node failures, and single link or node failures, and compare the results. In particular, we optimize the routing for multilayer networks where unused backup capacity of the link layer can be reused to redirect traffic on the network layer in case of an IP node failure.
