Border Gateway Protocol (BGP) Conformance and Performance Testing
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White Paper Border Gateway Protocol (BGP) Conformance and Performance Testing 26601 Agoura Road, Calabasas, CA 91302 | Tel: 818.871.1800 | Fax: 818.871.1805 | www.ixiacom.com Contents Border Gateway Protocol: Conformance and Performance Testing ............................... 3 Introduction ..............................................................................................................................3 What Is BGP? ............................................................................................................................3 Internal And External BGP ................................................................................................3 Historical Perspective ........................................................................................................4 How Does BGP Work? ..............................................................................................................4 Protocol Overview ..............................................................................................................5 AS Consistency ..................................................................................................................6 BGP Route Advertisement ................................................................................................6 Route Flap Damping ..........................................................................................................7 BGP Path Selection ...........................................................................................................7 BGP Policies And Traffic Engineering ...............................................................................8 BGP Attributes ................................................................................................................ 10 BGP Extensions ..................................................................................................................... 12 Route Reflectors ............................................................................................................. 12 AS Confederations .......................................................................................................... 13 BGP Multi-Protocol Extensions ...................................................................................... 13 BGP-MPLS VPN Support ................................................................................................. 14 Extension For IPv6 .......................................................................................................... 14 BGP Security ...................................................................................................................14 BGP Testing ........................................................................................................................... 15 Why test for BGP conformance and interoperability? .................................................. 15 Why test for BGP scalability and performance? ........................................................... 15 Ixia's approach to BGP testing .............................................................................................. 16 Conformance testing ...................................................................................................... 16 IxANVL™ .......................................................................................................................... 16 Protocol Emulations ....................................................................................................... 17 IxExplorer™ ..................................................................................................................... 17 IxScriptMate™ ................................................................................................................. 18 Conclusion ............................................................................................................................. 19 Appendix: BGP Testing Examples ....................................................................................20 Glossary ..............................................................................................................................30 Bibliography .......................................................................................................................33 Acknowledgements ...........................................................................................................33 Copyright © 1998-2004 Ixia. 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Internet: www.ixiacom.com 2 Copyright © 2004, Ixia BGP: Conformance and Performance Testing Border Gateway Protocol: Conformance and Performance Testing Introduction The relentless evolution of the Internet organizations with multiple links to one or continues to transform the way individuals, more service providers use BGP. as well as businesses, educational The increasing popularity of BGP stems institutions, and government organizations from its broad ability to distribute access, share, and communicate reachability information by selecting the information. Convergence of digital voice, best route to each destination according to video, and data, is further consolidating policies specified by network the Internet as a critical infrastructure. administrators. To manage the complexity One of the main routing protocols in the of BGP, however, a wide range of services, Internet and current de facto standard is applications, and hardware must be tested the Border Gateway Protocol (BGP). and validated. Indeed, a comprehensive Presently ubiquitous, BGP is a critical and well-designed conformance and component of the exponentially growing performance testing solution is crucial to network of routers that constitutes our successful BGP deployment. contemporary Internet. Carrier networks, as well as most large enterprise What Is BGP? BGP is a protocol for facilitating announce current routing to neighbor BGP communications between routers in speakers, which includes a list of all transit different autonomous systems. An ASs that must be used to reach the target autonomous system (AS) is a network or network. By carrying path information group of networks under a shared associated with a given destination technical administration and with common between autonomous systems, BGP routing policies. enables loop-free inter-domain routing. Network traffic in an AS is classified as BGP conveys information about AS-Path either local traffic or transit traffic. Local topologies and achieves inter-AS routing traffic either comes from or terminates in without constraining the underlying that AS, where either the IP host source network topology. An intra-AS routing address or destination address reside. Any protocol—that is, Interior Gateway Protocol other traffic traversing that AS constitutes (IGP), examples of which are Routing transit traffic. A major goal of BGP usage in Information Protocol (RIP), Open Shortest the Internet is to reduce transit traffic. Path First (OSPF), etc.—provides the routing within an autonomous system. In BGP advertises routes as a “promise” to some circumstances, BGP is used to carry data to the address space indicated exchange routes within an AS. In those by the IP prefix of the announced route. cases, it is called Internal BGP (I-BGP), as Generally, all routes in a BGP routing table opposed to External BGP (E-BGP) when outline Internet network connections. used between ASs. When a BGP router advertises to a neighbor that it has a path for reaching a Internal And External BGP specific IP prefix, the neighbor can be A BGP router can communicate with other confident that the advertising BGP speaker BGP routers in its own AS or in other ASs. is actively using that path to reach the Both the I-BGP and E-BGP implement the target destination. Route advertisements BGP protocol with a few different rules. All in BGP use the AS-Path attribute to I-BGP-speaking routers within the same AS BGP: Conformance and Performance Testing Copyright © 2004, Ixia 3 must peer with each other in a fully advertise 3rd-party information to their E- connected mesh. They are not required to BGP peers, by default. be physical neighbors, just to keep a TCP Figure 1 shows routers R1, R2, and R3 connection as a reliable transport using I-BGP to exchange routing mechanism. Because there is no loop information within the same AS, and router detection mechanism in I-BGP, all I-BGP- pairs R4-R2, R3-R5, and R4-R5 using E- speaking routers must not forward any 3rd- BGP to exchange routing information party routing information to their peers. In between ASs. contrast, E-BGP routers are able to Figure 1. Internal BGP (I-BGP) versus external BGP (E-BGP). Historical Perspective Several extensions for BGP-4 have been proposed since then. RFC 2283 defines Originally defined in RFC 1105, BGP BGP-4+, which includes IPV6 prefix became an Internet standard in 1989. It advertisement and other important replaced the older Exterior Gateway enhancements,