Combined Intra- and Inter-domain Traffic Engineering using Hot-Potato Aware Link Weights Optimization

A well-known approach to intradomain traffic engineering consists in finding the set of link weights that minimizes a network-wide objective function for a given intradomain traffic matrix. This approach is inadequate because it ignores a potential impact on interdomain routing. Indeed, the resulting set of link weights may trigger BGP to change the BGP next hop for some destination prefixes, to enforce hot-potato routing policies. In turn, this results in changes in the intradomain traffic matrix that have not been anticipated by the link weights optimizer, possibly leading to degraded network performance. We propose a BGP-aware link weights optimization method that takes these effects into account, and even turns them into an advantage. This method uses the interdomain traffic matrix and other available BGP data, to extend the intradomain topology with external virtual nodes and links, on which all the well-tuned heuristics of a classical link weights optimizer can be applied. A key innovative asset of our method is its ability to also optimize the traffic on the interdomain peering links. We show, using an operational network as a case study, that our approach does so efficiently at almost no extra computational cost.Comment: 12 pages, Short version to be published in ACM SIGMETRICS 2008, International Conference on Measurement and Modeling of Computer Systems, June 2-6, 2008, Annapolis, Maryland, US

End-Site Routing Support for IPv6 Multihoming

Multihoming is currently widely used to provide fault tolerance and traffic engineering capabilities. It is expected that, as telecommunication costs decrease, its adoption will become more and more prevalent. Current multihoming support is not designed to scale up to the expected number of multihomed sites, so alternative solutions are required, especially for IPv6. In order to preserve interdomain routing scalability, the new multihoming solution has to be compatible with Provider Aggregatable addressing. However, such addressing scheme imposes the configuration of multiple prefixes in multihomed sites, which in turn causes several operational difficulties within those sites that may even result in communication failures when all the ISPs are working properly. In this paper we propose the adoption of Source Address Dependent routing within the multihomed site to overcome the identified difficulties.Publicad

Analyzing BGP Instances in Maude

Analyzing Border Gateway Protocol (BGP) instances is a crucial stepin the design and implementation of safe BGP systems. Today, the analysis is amanual and tedious process. Researchers study the instances by manually constructingexecution sequences, hoping to either identify an oscillation or showthat the instance is safe by exhaustively examining all possible sequences. Wepropose to automate the analysis by using Maude, a tool based on rewriting logic.We have developed a library specifying a generalized path vector protocol, andmethods to instantiate the library with customized routing policies. Protocols canbe analyzed automatically by Maude, once users provide specifications of thenetwork topology and routing policies. Using our Maude library, protocols orpolicies can be easily specified and checked for problems. To validate our approach,we performed safety analysis of well-known BGP instances and actualrouting configurations

BGP-XM: BGP eXtended Multipath for Transit Autonomous Systems

Multipath interdomain routing has been proposed to enable flexible traffic engineering for transit Autonomos Systems (ASes). Yet, there is a lack of solutions providing maximal path diversity and backwards compatibility at the same time. The BGP-XM (Border Gateway Protocol-eXtended Multipath) extension presented in this paper is a complete and flexible approach to solve many of the limitations of previous BGP multipath solutions. ASes can benefit from multipath capabilities starting with a single upgraded router, and without any coordination with other ASes. BGP-XM defines an algorithm to merge into regular BGP updates information from paths which may even traverse different ASes. This algorithm can be combined with different multipath selection algorithms, such as the K-BESTRO (K-Best Route Optimizer) tunable selection algorithm proposed in this paper. A stability analysis and stable policy guidelines are provided. The performance evaluation of BGP-XM, running over an Internet-like topology, shows that high path diversity can be achieved even for limited deployments of the multipath mechanism. Further results for large-scale deployments reveal that the extension is suitable for large deployment since it shows a low impact in the AS path length and in the routing table size

Loop-freeness in multipath BGP through propagating the longest path

Proceeding of: International Workshop on the Network of the Future (FUT-NET 2009), In: IEEE International Conference on Communications Workshops, 2009. ICC Workshops 2009, Dresden, Germany, 14-18 June 2009The concurrent use of multiple paths through a communications network has the potential to provide many benefits, including better utilisation of the network and increased robustness. A key part of a multipath network architecture is the ability for routing protocols to install multiple routes over multiple paths in the routing table. In this paper we propose changes to local BGP processing that allow a BGP router to use multiple paths concurrently without compromising loop-freeness.This work has been partly funded by Trilogy, a research project (ICT-216372) supported by the European Community under its Seventh Framework Programme.European Community's Seventh Framework ProgramPublicad