L. Gao and J. Rexford. A Stable Internet Routing without Global Coordination. IEEE/ACMTransactions On Networking, 9(6):681--692, December 2001.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... A solution that uses a new route attribute called the route history to guarantee the convergence of SPVP was also proposed [8] Independently, Gao and Rexford have proposed a set of policy guidelines that guarantee convergence in E BGP without requiring any coordination among the different AS es [4]. The SPVP formalism, in conjunction with certain policy guidelines was later used to ensure E BGP convergence in networks where backup routing is used [3] I BGP has also been an area of much investigation. Several problems with route reflection in I BGP have been outlined by Dube and Scudder ....

L. Gao and J. Rexford. Stable Internet Routing without Global Coordination. In Proceedings of SIGMETRICS '00, Santa Clara, California, June 2000.

....that can be implemented using route filtering alone will be safe. This includes standard policies that determine which routes should be imported from and exported to customers, peers, and upstream providers [15] A more elaborate set of guidelines, together with correctness proofs, can be found in [4]. One difficulty with this approach is that many Internet Service Providers (ISPs) are in fact composed of multiple autonomous systems. Restrictions that make economic sense when we think of autonomous systems as independent ISPs may no longer hold when they are all owned by the same company. The ....

L. Gao and J. Rexford. Stable internet routing without global coordination. In SIGMETRICS 2000.

....can be violated; we also discuss why the use of a full mesh in iBGP is a sufficient condition for visibility. Previous work has noted that because BGP makes best path decisions based on local policy, certain sets of policies can result in routing configurations with no stable solution [16, 20]. That is, one AS may change its choice for a best route to a destination and readvertise that change to its neighbors, which will cause neighbors to change their choices for best routes, which will in turn affect the original AS s choice for a best route, and so forth. This situation is called a ....

.... wishes to keep its peering arrangements with A and C private (i.e. known only to itself) In this case, a reasonable routing policy is that B should tell A and C about its routes to its own destinations, as well as destinations in E, but should not tell A about routes heard from C, and vice versa [16]. However, if B sends a withdrawal to A for some destination that it never sent an advertisement for (e.g. a destination d in F ) then A learns something about B s other peers that it would not otherwise have known: specifically, A learns that B peers with some AS that either contains that ....

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GAO, L., AND REXFORD, J. Stable Internet routing without global coordination. IEEE/ACM Transactions on Networking (December 2001), 681--692.

....similar amounts of traffic to send to each other. Peering agreements are typically seen among the tier 1 or backbone providers at the top level of the Internet hierarchy, who provide national and global connectivity to their customers. For further details, see Marcus [13] Gao and Rexford [4], Norton [16] and Griffin and Wilfong [6] To understand the performance impact of peering relationships, we must first understand how these relationships affect the providers. When two providers form a link connecting their networks (which we shall refer to as a peering link) the traffic ....

....can be arbitrarily large. Our research forms part of a growing body of work on the implications of the current Internet interconnection paradigm. Much of this work has been focused on the protocol level, particularly on the failings of the BGP protocol used for interdomain routing; see, e.g. [4, 6, 7, 11]. Recently, however, several efforts at understanding the impact of provider economics at network design have also begun, including results by He and Walrand [8] Gopalakrishnan and Hajek [5] and Feigenbaum et al. 3] The analysis of these papers suggests that our analytical models may no ....

Gao, L., and Rexford, J. (2001). Stable internet routing without global coordination. IEEE/ACM Transactions on Networking, 9 (6): 681-692.

....network [7] To the best of our knowledge, ours is the first attempt at performing traffic engineering using BGP policies to control inter domain transit traffic flow. Other related work on BGP policies has focused primarily on providing guidelines to assure the stability of Internet routing [8] [12] Our problem formulations are specified as integer programs, and we show that the Generalized Assignment Problem (GAP) is a special case of our formulations. Solving GAP is wellknown to be NP hard, so we present heuristics for solving both the SES and the MES variants of our problem. We ....

L. Gao and J. Rexford, "Stable internet routing without global coordination, " in Proceedings of ACM SIGMETRICS, June 2000.

....The first thread started with the observation that there existed certain policy configurations which could cause persistent route oscillations in BGP [19] Later, Griffin and Wilfong [6] showed the intractability of determining a safe policy configuration for BGP. Finally, Rexford and Gao [20] proved that if BGP s policy expressiveness is confined to a simple set of policies, persistent route oscillations cannot occur. Independently, Labovitz et al. 21] showed that instability could occur even without policy conflicts because of implementation artifacts. Thus this first thread ....

Lixin Gao and Jennifer Rexford, "Stable Internet Routing Without Global Coordination," in Proceedings of ACM SIGMETRICS 2000.

.... A solution that uses a new route attribute called the route history to guarantee the convergence of SPVP was also proposed [8] Independently, Gao and Rexford have proposed a set of policy guidelines that guarantee convergence in E BGP without requiring any coordination among the different AS es [4]. The SPVP formalism, in conjunction with certain policy guidelines was later used to ensure E BGP convergence in networks where backup routing is used [3] 11 I BGP has also been an area of much investigation. Several problems with route reflection in I BGP have been outlined by Dube and Scudder ....

L. Gao and J. Rexford. Stable Internet Routing without Global Coordination. In Proceedings of ACM SIGMETRICS 2000.

....convergence in practice is a hard problem. BGP is designed to allow maximum flexibility in route preference policies. This makes it possible to set up a divergent BGP system while completely respecting the protocol standard. The problem of divergence is studied in several papers [3] 4] 5] [6], 7] We will focus our attention on a different problem the length of the convergence process. While conflicting policies Or u simply rejects (uv)P , while accepting (uv)Q 0 7803 7476 2 02 17.00 (c) 2002 IEEE. v u 0 P (u v)Q Fig. 1. A dispute between u and v that would cause ....

....policies. The second case study shows how to use Theorem 2 to prove the earlier result by Griffin, Wilfong and Shepherd about the convergence of timeless SPVP when the dispute digraph is acyclic. The third case study analyzes Gao and Rexford s proposal for ensuring convergence of SPVP [6]. The proposal represents some of the current best practices in configuring BGP policies. It uses the provider customer hierarchy of the Internet to restrict the preference functions and the flow of advertisements in a way that results in provable convergence. We use Theorem 2 to establish an ....

[Article contains additional citation context not shown here]

Lixin Gao and Jennifer Rexford, "Stable internet routing without global coordination," in ACM SIGMETRICS, 2000.

....convergence in practice is a hard problem. BGP is designed to allow maximum flexibility in route preference policies. This makes it possible to set up a divergent BGP system while completely respecting the protocol standard. The problem of divergence is studied in several papers [3] 4] 5] [6], 7] We will focus our attention on a different problem the length of the convergence process. While conflicting policies that would cause divergence are theoretically possible, many practitioners claim that such policies are rarely (if ever) used in practice. However, even then, it is ....

....policies. ffl The second case study shows how to use Theorem 2 to prove the earlier result by Griffin, Wilfong and Shepherd 6 about the convergence of timeless SPVP when the dispute digraph is acyclic. ffl The third case study analyzes Gao and Rexford s proposal for ensuring convergence of SPVP [6]. The proposal represents some of the current best practices in configuring BGP policies. It uses the provider customer hierarchy of the Internet to restrict the preference functions and the flow of advertisements in a way that results in provable convergence. We use Theorem 2 to establish an ....

[Article contains additional citation context not shown here]

Lixin Gao and Jennifer Rexford, "Stable internet routing without global coordination," in ACM SIGMETRICS, 2000.

....BGP allows the administrator of an autonomous system to specify arbitrarily complex policies. In BGP divergence, Griffin and Wilfong show that it is possible for autonomous systems to implement unsafe, or mutually unsatisfiable policies, which will result in persistent route oscillations. In [9], Gao et al. prove that adherence to specific common ISP policies, including provider and customer relationships, will guarantee convergence. The authors of all the above papers note that BGP divergence remains a theoretical finding and has not been observed in practice 1 . Our work explores a ....

....In this Section, we explore how routing policies and policy implementation mechanisms can impact both the number and length of possible ASPaths associated with a given route. The Internet retains a significant physical interconnection hierarchy with several tiers of service providers. In [9], Gao et al. describe the provider use of filters to implement several types of commercial peering relationships. In Figure 1, we present In Transit relationships Inbound Prefix filters to receive customer routes only 100 Peer relationships Outbound Communities 73 Prefix filters and ....

Lixin Gao and J. Rexford, "Stable Internet Routing Without Global Coordination, " Proc. of ACM SIGMETRICS, June 2000.

....BGP allows the administrator of an autonomous system to specify arbitrarily complex policies. In BGP divergence, Grin and Wilfong show that it is possible for autonomous systems to implement unsafe, or mutually unsatis able policies, which will result in persistent route oscillations. In [9], Gao et al. prove that adherence to speci c common ISP policies, including provider and customer relationships, will guarantee convergence. The authors of all the above papers note that BGP divergence remains a theoretical nding and has not been observed in practice. Our work explores a ....

....illustrate the role these policies and speci c implementation mechanisms play in the ow of routing information. The Internet retains a signi cant physical interconnection hierarchy with several tiers of service providers. We illustrate this hierarchy with an example topology in Figure 2. In [9], Gao et al. describe the provider use of lters to implement several types of commercial peering relationships. Based on this discussion and the results of our survey of Internet provider policies, we describe three categories of inter provider relationships. Unlike the taxonomy used by Gao et ....

Lixin Gao and J. Rexford, \Stable Internet Routing Without Global Coordination, " Proc. of ACM SIGMETRICS, June 2000.

.... routing tables, upstream ASs aggregate the advertisements of several downstream ASs with contiguous address ranges into one advertisement of a larger AS [2] Also, with existing BGP route advertisement schemes, where not all possible AS paths are circulated on the Internet due to policy routing [8], it is unavoidable that BGP routing tables don t capture all existing AS links. Finally, being able to identify AS border routers, we may further characterize inter AS connections. Tangmunarunkit et al. 18] have also attempted to infer AS connectivity from router level topology. Our approach ....

....inferred AS map not found in the Oregon BGP routing table. We cannot consider these links erroneous; for example, they could simply be invisible to the Oregon BGP route server, either because of route aggregation or because of BGP export policies that constrain re advertisement of peering routes [8]. Assuming that our AS mapping table is fairly accurate, we next investigate the causes of these incorrect AS paths. One possible culprit is the path trace mechanism of the traceroute tool. The discovery of a router level path by the traceroute tool is based on retrieving the source address of ....

L. Gao and J. Rexford. Stable internet routing without global coordination. In Proc. ACM SIGMETRICS, June 2000.

....BGP allows the administrator of an autonomous system to specify arbitrarily complex policies. In BGP divergence, Griffin and Wilfong show that it is possible for autonomous systems to implement unsafe, or mutually unsatisfiable policies, which will result in persistent route oscillations. In [9], Gao et al. prove that adherence to specific common ISP policies, including provider and customer relationships, will guarantee convergence. The authors of all the above papers note that BGP divergence remains a theoretical finding and has not been observed in practice 1 . Our work explores a ....

....In this Section, we explore how routing policies and policy implementation mechanisms can impact both the number and length of possible ASPaths associated with a given route. The Internet retains a significant physical interconnection hierarchy with several tiers of service providers. In [9], Gao et al. describe the provider use of filters to implement several types of commercial peering relationships. In Figure 1, we present In Transit relationships Inbound Prefix filters to receive customer routes only 100 Peer relationships Outbound Communities 73 Prefix filters and ....

Lixin Gao and J. Rexford, "Stable Internet Routing Without Global Coordination, " Proc. of ACM SIGMETRICS, June 2000.

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L. Gao and J. Rexford. A Stable Internet Routing without Global Coordination. IEEE/ACMTransactions On Networking, 9(6):681--692, December 2001.

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GAO,L.,AND REXFORD, J. A Stable Internet Routing without Global Coordination. IEEE/ACM Transactions On Networking 9, 6 (December 2001), 681--692.

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L. Gao, J. Rexford, `Stable Internet routing without global coordination', in Proc. ACM SIGMETRICS, June 2000

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L. Gao and J. Rexford, "Stable Internet routing without global coordination," IEEE/ACM Trans. Networking, vol. 9, pp. 681--692, December 2001.

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L. Gao and J. Rexford, "Stable Internet routing without global coordination," IEEE/ACM Trans. Networking, vol. 9, pp. 681--692, December 2001.

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L. Gao and J. Rexford, \Stable Internet routing without global coordination," in Proc. ACM SIGMETRICS, June 2000.

.... by the same institution may have a sibling relationship, where each AS exports all of its routes to the other AS [10] Other AS pairs may have backup relationships to provide connectivity in the event of a failure [16] Alternatively, two ASes may peer indirectly through an intermediate AS [17]. Also, an AS pair may have different relationships for certain blocks of IP addresses; for example, an AS in Europe may be a customer of an AS in the United States for some destinations and a peer for others. Router misconfiguration may also cause violations in the export rules. For example, a ....

....an edge. When considering a partial view from a tier 1 AS that does not have any upstream providers, every path consists of zero or one peer peer edges followed by a downhill portion consisting of provider customer edges. In practice, we expect the provider customer relationship to be acyclic [17]. For example, if in Figure 1 there is an additional edge between A and C, then since A is a customer of B and B is a customer of C, C cannot be a customer of A but is rather an additional provider to A. Hence, the partial view from a tier 1 AS would tend to be acyclic. In this case, successive ....

L. Gao and J. Rexford, "Stable Internet routing without global coordination, " IEEE/ACM Trans. Networking, vol. 9, no. 6, pp. 681--692, December 2001.

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L. Gao and J. Rexford, "Stable Internet routing without global coordination," IEEE/ACM Trans. Networking 9, pp. 681--692, December 2001.

....practices or agreements with neighbors often impose constraints on the relative preference of routes learned from customers, peers, and providers. For example, network operators typically prefer routes learned from downstream customers over routes learned from peers and upstream providers [10, 22] . Alternatively, a customer may request that a path be treated as a backup route by giving preference to other paths. These constraints can be obeyed by defining a distinct range of local preference values for each class of routes and by requiring the import policies to adhere to these ....

L. Gao and J. Rexford, "Stable Internet routing without global coordination," in Proc. ACM SIGMETRICS, June 2000.

....Graduate Group Chair Acknowledgements Chapters 3, 4, 5 are based on joint work with Carl Gunter and Karthikeyan Bhargavan who I have been privileged to have as colleagues. Their help was of crucial importance for this thesis. The work presented in Chapter 6 extends the research ideas from [20, 19, 21, 16, 17] by Timothy G. Grin, F. Bruce Shepherd, Gordon Wilfong, Lixin Gao and Jennifer Rexford. I wish to thank them for the inspiration they provided. I would like to thank the CISCO Corporation, and especially Alvaro Retana, for supporting my research on BGP. I would also like to thank Rajeev Alur, ....

....problem for BGP on the Internet is not well understood. Grin and Wilfong [20] demonstrated that even if the BGP topology of the Internet were known, it would be infeasible in principle to decide whether it might display oscillations. Sucient conditions for guaranteed convergence are presented in [19, 17]. Deeper understanding of the convergence properties of BGP is likely to be an active research area during the next few years. Properties that a protocol is supposed to satisfy are called requirements. Routing protocol requirements are often speci ed during the design phase. Proving or ....

[Article contains additional citation context not shown here]

Lixin Gao and Jennifer Rexford. Stable internet routing without global coordination. In ACM SIGMETRICS, 2000.

.... by the same institution may have a sibling relationship, where each AS exports all of its routes to the other AS [10] Other AS pairs may have backup relationships to provide connectivity in the event of a failure [16] Alternatively, two ASes may peer indirectly through an intermediate AS [17]. Also, an AS pair may have different relationships for certain blocks of IP addresses; for example, an AS in Europe may be a customer of an AS in the United States for some destinations and a peer for others. Router misconfiguration may also cause violations in the export rules. For example, a ....

....an edge. When considering a partial view from a tier 1 AS that does not have any upstream providers, every path consists of zero or one peer peer edges followed by a downhill portion consisting of provider customer edges. In practice, we expect the provider customer relationship to be acyclic [17]. For example, if in Figure 1 there is an additional edge between A , then since A is a customer of B and B is a customer ofC ,C cannot be a customer of A but is rather an additional provider to A. Hence, the partial view from a tier 1 AS would tend to be acyclic. In this case, successive ....

L. Gao and J. Rexford, "Stable Internet routing without global coordination, " IEEE/ACM Trans. Networking, vol. 9, no. 6, pp. 681--692, December 2001.

.... two ASes operated by the same institution may have a sibling relationship where each AS provides transit service for the other [10] Other AS pairs may have backup relationships to provide connectivity in the event of a failure [15] Alternatively, two ASes may peer indirectly through a transit AS [16]. Also, an AS pair may have different relationships for certain blocks of IP addresses; for example, an AS in Europe may be a customer of an AS in the United States for some destinations and a peer for others. Router misconfiguration may also cause violations in the export rules. For example, a ....

....AS graph depends on the position of the AS in the Internet hierarchy. When viewed from a tier 1 AS that does not have any upstream providers, every path consists of zero or one peer peer edges followed by a downhill portion. In practice, we expect the providercustomer relationship to be acyclic [16]. That is, if u is a customer of v and v is a customer of w, then w is not a customer of u. Hence, the partial view from a tier 1 AS would tend to be acyclic. In this case, successive pruning would identify provider customer relationships. However, in other scenarios, the graph may have cycles. ....

L. Gao and J. Rexford, "Stable Internet routing without global coordination," in Proc. ACM SIGMETRICS, June 2000.

....the AS has with each of the neighboring autonomous systems. This information can be used to classify each edge link as a customer, peering, or provider link [15] based on the remote AS of the BGP session. The classification may have implications on the desired BGP import and export policies [16, 17]. Indeed, policies such as BGP import and export policies or default access lists could be contained in a separate input file. ffl Description fields: Extra information may be embedded in description fields in the router configuration files. For example, the description could indicate the length ....

....Checks An operational network may have high level policies that result in additional error checks. For example, certain checks could be customized based on the type of the router or link. A BGP session with a customer may employ different import and export policies than a session with a peer [17]. These BGP policies can be codified in separate input files, and checked against each BGP session in the router configuration files. Similarly, conventions for iBGP configuration can be expressed in a separate input file. For example, an AS may use route reflectors to reduce the overhead of ....

L. Gao and J. Rexford, "Stable Internet routing without global coordination," in Proc. ACM SIGMETRICS, June 2000.

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L. Gao and J. Rexford, \A stable Internet routing without global coordination," in Proc. ACM SIGMETRICS, June 2000. 14

....policies safe if they can never lead to BGP divergence. Verifying the safety of a set of routing policies is computationally expensive [8] and would require ASes to reveal their (often proprietary) routing policies. Safety is not guaranteed even if each AS conforms to NER. However, Gao and Rexford [9] present additional guidelines that guarantee safety. They present two basic ap 2 proaches. In the first, each AS uses the shortest paths rule and prefers routes with shorter AS paths. In the second, each AS always prefers customer routes over peer and provider routes. This second approach ....

....reliability of the network without the overhead of installing additional links. In order to increase network reliability, backup routing is often allowed to violate some of the rules imposed on normal routing. In particular, backup routing present two challenges for the guidelines presented in [9]. First, implementing peer to peer backups requires the violation of NER. Second, backup routing may violate the path preference guidelines of [9] For example, a provider route may be preferred over a customer route if the customer route is a backup route. The current paper investigates how the ....

[Article contains additional citation context not shown here]

L. Gao and J. Rexford, "Stable Internet routing without global coordination," in Proc. ACM SIGMETRICS, June 2000.

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L. Gao and J. Rexford. Stable Internet Routing Without Global Coordination. IEEE/ACM Trans. Networking, 9(6):681--692, December 2001.

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GAO, L., AND REXFORD, J. Stable Internet routing without global coordination. In Proc. ACM SIGMETRICS (2001).

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L. Gao and J. Rexford. Stable Internet Routing without Global Coordination. In Proc. of ACM SIGMETRICS, June 2000.

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L. Gao and J. Rexford. Stable internet routing without global coordination. In SIGMETRICS, 2000.

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L. Gao and J. Rexford. Stable Internet routing without global coordination. IEEE/ACM Transactions on Networking, 9(6):307--317, 2001.

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L. Gao and J. Rexford. Stable Internet Routing without Global Coordination. In Proceedings of SIGMETRICS '00, Santa Clara, California, June 2000.

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L. Gao and J. Rexford. Stable internet routing without global coordination. In SIGMETRICS 2000.

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L. Gao and J. Rexford. Stable internet routing without global coordination. In SIGMETRICS, 2000.

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L. Gao and J. Rexford. Stable internet routing without global coordination. In SIGMETRICS, 2000.

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L. Gao and J. Rexford. Stable Internet Routing Without Global Coordination. ACM/IEEE Trans. on Networking, 9(6): 681--692, 2001.

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L. Gao und J. Rexford, "Stable Internet Routing Without Global Coordination," in Proceedings of ACM SIGMETRICS, June 2000

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L. Gao and J. Rexford. Stable Internet Routing without Global Coordination. In Proc. ACM SIGMETRICS, pages 307--317, June 2000.

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L. Gao and J. Rexford. Stable Internet Routing Without Global Coordination. ACM/IEEE Trans. on Networking, 9(6): 681--692, 2001.

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L. Gao and J. Rexford. "Stable Internet Routing without Global Coordination ". In Proc. ACM SIGMETRICS, June 2000.

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GAO, L., AND REXFORD, J. Stable Internet routing without global coordination. IEEE/ACM Transactions on Networking (December 2001), 681--692.

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L. Gao and J. Rexford. "Stable Internet Routing without Global Coordination ". In Proc. ACM SIGMETRICS, June 2000.

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L. Gao and J. Rexford. Stable internet routing without global coordination. In IEEE/ACM Transactions on Networking, 2001.

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Lixin Gao and Jennifer Rexford. Stable internet routing without global coordination. In Proceedings of the 2000.

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L. Gao and J. Rexford. Stable Internet Routing Without Global Coordination. In Proc. of ACM SIGMETRICS, 2000.

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Lixin Gao and Jennifer Rexford. Stable Internet Routing Without Global Coordination. In Proceedings of ACM SIGMETRICS 2000.

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L. Gao and J. Rexford, "A stable internet routing without global coordination," in Proceedings of ACM SIGMETRICS '00, June 2000.

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L. Gao and J. Rexford, "Stable Internet Routing Without Global Coordination," in Proc. of ACM SIGMETRICS 2000.

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