Internet routing paths stability model and relation to forwarding paths

Analysis of real datasets to characterize the local stability properties of the Internet routing paths suggests that extending the route selection criteria to account for such property would not increase the routing path length. Nevertheless, even if selecting a more stable routing path could be considered as valuable from a routing perspective, it does not necessarily imply that the associated forwarding path would be more stable. Hence, if the dynamics of the Internet routing and forwarding system show different properties, then one can not straightforwardly derive the one from the other. If this assumption is verified, then the relationship between the stability of the forwarding path (followed by the traffic) and the corresponding routing path as selected by the path-vector routing algorithm requires further characterization. For this purpose, we locally relate, i.e., at the router level, the stability properties of routing path with the corresponding forwarding path. The proposed stability model and measurement results verify this assumption and show that, although the main cause of instability results from the forwarding plane, a second order effect relates forwarding and routing path instability events. This observation provides the first indication that differential stability can safely be taken into account as part of the route selection process

CleanBGP: Verifying the consistency of BGP data

Copyright © 2008 IEEEBGP data contains artifacts introduced by the measurement infrastructure which can substantially affect analysis. This is especially important in operational systems where "crying wolf" will result in an operator ignoring alarms. In this paper, we investigate the causes of measurement artifacts in BGP data - cross-checking and using properties of the data to infer the presence of an artifact and minimize its impact. We have developed a prototype tool, CleanBGP, which detects and corrects the effects of artifacts in BGP data, which we believe should be used prior to the analysis of such data. CleanBGP provides the user with an understanding of the artifacts present, a mechanism to remove their effects, and consequently the limitations of results can be fully quantified.Ashley Flavel, Olaf Maennely, Belinda Chiera, Matthew Roughan and Nigel Bea

BGRP: A Tree-Based Aggregation Protocol for Inter-domain Reservations

Resource reservation needs to accommodate the rapidly growing size and increasing service diversity of the Internet. Recently, hierarchical architectures have been proposed that provide domain-level reservation.However, it is not clear that these proposals can set up and maintain reservations in an efficient and scalable fashion. In this paper, we describe a distributed architecture and protocol,called the Border Gateway Reservation Protocol (BGRP), for inter-domain resource reservation that can scale in terms of message processing load. state storage and bandwidth. Each stub or transit domain may use its own intra-domain resource reservation protocol. BGRP builds a sink tree for each of the stub domains. Each sink tree aggregates bandwidth reservations from all data sources in the network.Since backbone routers only maintain the sink tree information, the total number of reservation states at each router scales, in the worst case, linearly with the number of domains in the Internet. BGRP relies on differentiated services for data forwarding. As a result, the number of packet classifier entries is small, not the number of micro-flows.To reduce the protocol message traffic, routers may reserve domain bandwidth beyond the current load so that sources can join or leave the tree or change their reservation without having to send messages all the way to the root for every such change. We use``soft state'' to maintain reservations. In contrast to RSVP, refresh messages are delivered reliably, allowing us to reduce the refresh frequency

A distributed method for dynamic resolution of BGP oscillations

RR 05069International audienceAutonomous Systems (AS) in the Internet use different protocols for internal and external routing. BGP is the only external protocol. It allows ASes to define their own routing policy independently. Many papers cited in reference deal with a divergence behavior due to this flexibility. In fact, when routing policies are not conflicting, BGP is self-stabilising, which means that whatever the network configuration, BGP converges to a stable solution. Unfortunately, as experienced on the Internet, AS routing policies may be uncoherent, thus generating oscillations. In this paper we propose a distributed dynamic method for detecting and solving oscillations of BGP. It respects private policy choices and requires only a few low level constraints in order to converge to a stable solution. Essentially, a router has to maintain only local path stateful information to detect instabilities. In this case, it generates and launches a token linked to a route. Each router makes the decision to forward or not the token according to local data and local policy. If the originating router receives back the token, then it marks the route as barred. Nevertheless, routes may furtherly be unmarked. Finally, we express and define what coherence between routing policies means