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73
On Inferring Autonomous System Relationships in the Internet
- IEEE/ACM Transactions on Networking
, 2000
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Stable Internet Routing Without Global Coordination
- IEEE/ACM Transactions on Networking
, 2000
"... The Border Gateway Protocol (BGP) allows an autonomous system (AS) to apply diverse local policies for selecting routes and propagating reachability information to other domains. However, BGP permits ASes to have conflicting policies that can lead to routing instability. This paper proposes a set of ..."
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Cited by 343 (44 self)
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The Border Gateway Protocol (BGP) allows an autonomous system (AS) to apply diverse local policies for selecting routes and propagating reachability information to other domains. However, BGP permits ASes to have conflicting policies that can lead to routing instability. This paper proposes a set of guidelines for an AS to follow in setting its routing policies, without requiring coordination with other ASes. Our ap-proach exploits the Internet's hierarchical structure and the commercial relationships between ASes to impose a partial order on the set of routes to each destination. The guide-lines conform to conventional traffic-engineering practices of ISPs, and provide each AS with significant flexibility in se-lecting its local policies. Furthermore, the guidelines ensure route convergence even under changes in the topology and routing policies. Drawing on a formal model of BGP, we prove that following our proposed policy guidelines guaran-tees route convergence. We also describe how our method-ology can be applied to new types of relationships between ASes, how to verify the hierarchical AS relationships, and how to realize our policy guidelines. Our approach has sig-nificant practical value since it preserves the ability of each AS to apply complex local policies without divulging its BGP configurations to others. 1.
Understanding BGP Misconfiguration
- In Proc. ACM SIGCOMM
, 2002
"... It is well-known that simple, accidental BGP configuration errors can disrupt Internet connectivity. Yet little is known about the frequency of misconfiguration or its causes, except for the few spectacular incidents of widespread outages. In this paper, we present the first quantitative study of BG ..."
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Cited by 302 (14 self)
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It is well-known that simple, accidental BGP configuration errors can disrupt Internet connectivity. Yet little is known about the frequency of misconfiguration or its causes, except for the few spectacular incidents of widespread outages. In this paper, we present the first quantitative study of BGP misconfiguration. Over a three week period, we analyzed routing table advertisements from 23 vantage points across the Internet backbone to detect incidents of misconfiguration. For each incident we polled the ISP operators involved to verify whether it was a misconfiguration, and to learn the cause of the incident. We also actively probed the Internet to determine the impact of misconfiguration on connectivity.
Detecting BGP Configuration Faults with Static Analysis
- in Proc. Networked Systems Design and Implementation
, 2005
"... The Internet is composed of many independent autonomous systems (ASes) that exchange reachability information to destinations using the Border Gateway Protocol (BGP). Network operators in each AS configure BGP routers to control the routes that are learned, selected, and announced to other routers. ..."
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Cited by 188 (15 self)
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The Internet is composed of many independent autonomous systems (ASes) that exchange reachability information to destinations using the Border Gateway Protocol (BGP). Network operators in each AS configure BGP routers to control the routes that are learned, selected, and announced to other routers. Faults in BGP configuration can cause forwarding loops, packet loss, and unintended paths between hosts, each of which constitutes a failure of the Internet routing infrastructure. This paper describes the design and implementation of rcc, the router configuration checker, a tool that finds faults in BGP configurations using static analysis. rcc detects faults by checking constraints that are based on a high-level correctness specification. rcc detects two broad classes of faults: route validity faults, where routers may learn routes that do not correspond to usable paths, and path visibility faults, where routers may fail to learn routes for paths that exist in the network. rcc enables network operators to test and debug configurations before deploying them in an operational network, improving on the status quo where most faults are detected only during operation. rcc has been downloaded by more than sixty-five network operators to date, some of whom have shared their configurations with us. We analyze network-wide configurations from 17 different ASes to detect a wide variety of faults and use these findings to motivate improvements to the Internet routing infrastructure. 1
Traffic engineering with traditional IP routing protocols
- IEEE Communications Magazine
, 2002
"... Traffic engineering involves adapting the routing of traffic to the network conditions, with the joint goals of good user performance and efficient use of network resources. In this paper, we describe an approach to intradomain traffic engineering that works within the existing deployed base of Inte ..."
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Cited by 182 (21 self)
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Traffic engineering involves adapting the routing of traffic to the network conditions, with the joint goals of good user performance and efficient use of network resources. In this paper, we describe an approach to intradomain traffic engineering that works within the existing deployed base of Interior Gateway Protocols (IGPs), such as Open Shortest Path First (OSPF) and Intermediate System-Intermediate System (IS-IS). We explain how to adapt the configuration of link weights, based on a network-wide view of the traffic and topology within a domain. In addition, we summarize the results of several studies of techniques for optimizing OSPF/IS-IS weights to the prevailing traffic. The paper argues that traditional shortest-path routing protocols are surprisingly effective for engineering the flow of traffic in large IP networks. 1
On static reachability analysis of IP networks
- In Proc. IEEE INFOCOM
, 2005
"... document without permission of its author may be prohibited by law. ..."
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Cited by 95 (14 self)
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Modeling the Routing of an Autonomous System with C-BGP
- IEEE Network Magazine
, 2005
"... Today, the complexity of ISPs' networks make it difficult to investigate the implications of internal or external changes on the distribution of traffic across their network. In this article we explain the complexity of building models of large ISPs' networks. We describe the various aspec ..."
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Cited by 58 (11 self)
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Today, the complexity of ISPs' networks make it difficult to investigate the implications of internal or external changes on the distribution of traffic across their network. In this article we explain the complexity of building models of large ISPs' networks. We describe the various aspects important to understanding the routing inside an AS. We present an open source routing solver, C-BGP, that eases the investigation of changes in the routing or topology of large networks. We illustrate how to build a model of an ISP on a real transit network and apply the model on two "what-if" scenarios. The first scenario studies the impact of changes in the Internet connectivity of a transit network. The second investigates the impact of failures in its internal topology.
Analyzing BGP Policies: Methodology and Tool
- in Proc. IEEE INFOCOM
, 2004
"... The robustness of the Internet relies heavily on the robustness of BGP routing. BGP is the glue that holds the Internet together: it is the common language of the routers that interconnect networks or Autonomous Systems(AS). The robustness of BGP and our ability to manage it effectively is hampered ..."
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Cited by 46 (2 self)
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The robustness of the Internet relies heavily on the robustness of BGP routing. BGP is the glue that holds the Internet together: it is the common language of the routers that interconnect networks or Autonomous Systems(AS). The robustness of BGP and our ability to manage it effectively is hampered by the limited global knowledge and lack of coordination between Autonomous Systems. One of the few efforts to develop a globally analyzable and secure Internet is the creation of the Internet Routing Registries (IRRs). IRRs provide a voluntary detailed repository of BGP policy information. The IRR effort has not reached its full potential because of two reasons: a) extracting useful information is far from trivial, and b) its accuracy of the data is uncertain.
A Case Study of OSPF Behavior in a Large Enterprise Network
- In ACM SIGCOMM Internet Measurement Workshop
, 2002
"... Abstract — Open Shortest Path First (OSPF) is widely deployed in IP networks to manage intra-domain routing. OSPF is a link-state protocol, in which routers reliably flood “Link State Advertisements ” (LSAs), enabling each to build a consistent, global view of the routing topology. Reliable performa ..."
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Cited by 45 (9 self)
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Abstract — Open Shortest Path First (OSPF) is widely deployed in IP networks to manage intra-domain routing. OSPF is a link-state protocol, in which routers reliably flood “Link State Advertisements ” (LSAs), enabling each to build a consistent, global view of the routing topology. Reliable performance hinges on routing stability, yet the behavior of large operational OSPF networks is not well understood. In this paper, we provide a case study on the characteristics and dynamics of LSA traffic for a large enterprise network. This network consists of several hundred routers, distributed in tens of OSPF areas, and connected by LANs and private lines. For this network, we focus on LSA traffic and analyze: (a) the class of LSAs triggered by OSPF’s soft-state refresh, (b) the class of LSAs triggered by events that change the status of the network, and (c) a class of “duplicate ” LSAs received due to redundancy in OSPF’s reliable LSA flooding mechanism. We derive the baseline rate of refresh-triggered LSAs automatically from network configuration information. We also investigate finer time scale statistical properties of this traffic, including burstiness, periodicity, and synchronization. We discuss root causes of event-triggered and duplicate LSA traffic, as well as steps identified to reduce this traffic (e.g., localizing a failing router or changing the OSPF configuration).
Unraveling the Complexity of Network Management
"... Operator interviews and anecdotal evidence suggest that an operator’s ability to manage a network decreases as the network becomes more complex. However, there is currently no way to systematically quantify how complex a network’s design is nor how complexity may impact network management activities ..."
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Cited by 43 (4 self)
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Operator interviews and anecdotal evidence suggest that an operator’s ability to manage a network decreases as the network becomes more complex. However, there is currently no way to systematically quantify how complex a network’s design is nor how complexity may impact network management activities. In this paper, we develop a suite of complexity models that describe the routing design and configuration of a network in a succinct fashion, abstracting away details of the underlying configuration languages. Our models, and the complexity metrics arising from them, capture the difficulty of configuring control and data plane behaviors on routers. They also measure the inherent complexity of the reachability constraints that a network implements via its routing design. Our models simplify network design and management by facilitating comparison between alternative designs for a network. We tested our models on seven networks, including four university networks and three enterprise networks. We validated the results through interviews with the operators of five of the networks, and we show that the metrics are predictive of the issues operators face when reconfiguring their networks. 1