Wresting control from BGP: Scalable fine-grained route control

International Journal of Network Management, 2005

Many Internet Service Providers tune the configuration of the Border Gateway Protocol on their routers to control their traffic. Content providers often need to control their outgoing traffic while access providers need to control their incoming traffic. We show, by means of measurements and simulations, that controlling the flow of the incoming interdomain traffic is a difficult problem. For this purpose, we first rely on detailed measurements to show the limitations of AS-Path prepending. Then, we show by using large-scale simulations that the difficulty of controlling the flow of the incoming traffic lies in the difficulty of predicting which BGP route will be selected by distant ASes.

Routing protocols are important to exchange routing information between neighboring routers. Such information is used to update routing tables and to share information about status of the network so that traffics to appropriate destinations will be fast and efficient. Different types of routing protocols are in widespread use across the Internet. Apart from determining optimal routing paths and carrying traffics through the networks, these routing protocols should have additional functionalities to support network policies, traffic engineering and security. In this paper we discuss the use of one such routing protocol, the Border Gateway Protocol (BGP) which is the industry standard. We also present an algorithm in which each Autonomous System (AS) decides how to forward its traffic satisfying end-to-end-QoS for its users and services. Our proposed algorithm is dynamic in that network status and route advertisements, which change with time and based on traffic loads in the network, are monitored and taken as input to the final decision on traffic forwarding between ASs.

Proceedings of the 2006 SIGCOMM workshop on Internet network management - INM '06, 2006

Increased use of demanding network applications, as well as the increase of unwanted network traffic in the form of DDoS attacks, are putting new pressures on service providers to meet the expectations of customers in terms of network availability and performance. Providers are expected to deal with potential problems in near real-time fashion. Further, many of these demanding application, such as VoIP and online gaming, are very sensitivity to even small periods of disruption. In this work we therefore specifically focus on dynamic connectivity management, which we broadly define as the ability to dynamically manage how and where traffic flows across a network. Because it is intimately involved with how traffic flows through the network, BGP would be an ideal candidate for many of these management tasks. Unfortunately, BGP is itself a complicated protocol and up to now the prospect of using it to perform routine management tasks has not been considered a feasible approach. In this paper we show how the simplification introduced by a centralized Intelligent Route Service Control Point (IRSCP) that allows route selection to be performed outside the routers and also allows such route selection to be informed by external network intelligence, address this quandary. We present several examples of connectivity management tasks that can benefit from our approach. We describe our trial implementation of the IRSCP and show how our approach raise the level of abstraction, allowing operators to focus on what functions need to be performed, rather than getting bogged down with how to perform them.

Proceedings of the Ninth ACM SIGCOMM Workshop on Hot Topics in Networks - Hotnets '10, 2010

Today's interdomain routing system does not perform well, because the BGP protocol converges slowly, selects paths without regard for performance, does not support multipath routing, and has numerous security vulnerabilities. Rather than adding mechanisms to an already complex protocol, or redesigning interdomain routing from scratch, we propose making BGP simpler, and handling issues such as dataplane performance and security where they belong-outside the routing protocol. We propose a transition from today's path-based routing (where routing decisions depend on the entire AS-PATH) to next-hop routing-a solution that selects and exports routes based only on the neighboring domain. Based on theoretical and experimental results, we show that next-hop routing leads to significantly better network performance than path-based routing, and is especially effective at preventing the most serious BGP convergence problems, alongside other advantages (including being more amenable to multipath routing and a reduced attack surface). a simple "consistent filtering" rule [11] when exporting routes. That is, we relegate the AS-PATH to its traditional role in loop detection. We show, both analytically and experimentally, that next-hop routing achieves significantly better network performance than traditional path-based routing in two important respects:

Networked Systems Design and Implementation, 2005

The routers in an Autonomous System (AS) must distribute the information they learn about how to reach external destinations. Unfortunately, today's internal Border Gateway Protocol (iBGP) architectures have serious problems: a "full mesh" iBGP configuration does not scale to large networks and "route reflection" can introduce problems such as protocol oscillations and persistent loops. Instead, we argue that a Routing Control Platform (RCP) should collect information about external destinations and internal topology and select the BGP routes for each router in an AS. RCP is a logicallycentralized platform, separate from the IP forwarding plane, that performs route selection on behalf of routers and communicates selected routes to the routers using the unmodified iBGP protocol. RCP provides scalability without sacrificing correctness. In this paper, we present the design and implementation of an RCP prototype on commodity hardware. Using traces of BGP and internal routing data from a Tier-1 backbone, we demonstrate that RCP is fast and reliable enough to drive the BGP routing decisions for a large network. We show that RCP assigns routes correctly, even when the functionality is replicated and distributed, and that networks using RCP can expect comparable convergence delays to those using today's iBGP architectures.

We analyze several types of interdomain traffic engineering techniques. First, we briefly describe interdo-main routing and the BGP protocol. Then, we summarize the characteristics of interdomain traffic based on measure-ments with two different ISPs. We evaluate how a typical ISP can select its upstream providers and show that with the BGP decision process many routes are selected non-deterministically. We then evaluate with simulations the perfor-mance of BGP-based traffic engineering techniques that are currently used on the Internet and show their limitations.

IEEE Network, 2005

The Internet has quickly evolved into a vast global network owned and operated by thousands of different administrative entities. During this time, it became apparent that vanilla shortest-path routing would be insufficient to handle the myriad operational, economic, and political factors involved in routing. ISPs began to modify routing configurations to support routing policies, i.e. goals held by the router's owner that controlled which routes were chosen and which routes were propagated to neighbors. BGP, originally a simple path-vector protocol, was incrementally modified over time with a number of mechanisms to support policies, adding substantially to the complexity. Much of the mystery in BGP comes not only from the protocol complexity but also from a lack of understanding of the underlying policies and the problems ISPs face which they address. In this paper we shed light on goals operators have and their resulting routing policies, why BGP evolved the way it did, and how common policies are implemented using BGP. We also discuss recent and current work in the field that aims to address problems that arise in applying and supporting routing policies.

IEEE Network, 1999

In today's Internet, individuals, campuses, and organizations obtain IP connectivity from transit providers. Internet interprovider routing is governed by bilateral traffic exchange agreements between providers. Such independently established policies can adversely impact the stability and analyzability of Internet routing. We describe an architecture for coordinating Internet routing policies. This architecture allows providers to publish high-level specifications of their policies, and to analyze the effects of their policies on Internet routing. Several pieces of the architecture have been implemented and are in production use; we also discuss the experiences gleaned from these deployments

Lecture Notes in Computer Science, 2011

The Internet is organized as a collection of networks called Autonomous Systems (ASes). The Border Gateway Protocol (BGP) is the glue that connects these administrative domains. Communication is thus possible between users worldwide and each network is responsible of sharing reachability information to peers through BGP. Protocol extensions are periodically added because the intended use and design of BGP no longer fit the current demands. Scalability concerns make the required iBGP full mesh difficult to achieve in today's large networks and therefore network operators resort to confederations or Route Reflectors (RRs) to achieve full connectivity. These two options come with a set of flaws of their own such as persistent routing oscillations, deflections, forwarding loops etc. In this paper we propose a new architecture for the redistribution of external routes inside an AS. Instead of relying on the usual statically configured set of iBGP sessions, we propose to use an overlay of routing instances that are collectively responsible for (i) the exchange of routes with other ASes, (ii) the storage of internal and external routes, (iii) the storage of the entire routing policy configuration of the AS and (iv) the computation and redistribution of the best routes towards Internet destinations to each router of the AS.

Sigmetrics Performance Evaluation Review, 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 guidelines for an AS to follow in setting its routing policies, without requiring coordination with other ASes. Our approach 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 guidelines conform to conventional traffic-engineering practices of ISPs, and provide each AS with significant flexibility in selecting 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 guarantees route convergence. We also describe how our methodology 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 significant practical value since it preserves the ability of each AS to apply complex local policies without divulging its BGP configurations to others.