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BGP topics to be discussed in the next few weeks: Excessive route update Routing instability BGP policy issues BGP route slow convergence problem Interaction between BGP/IGP and among BGP components Anti-IP-spoofing with BGP New EGP proposals.
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BGP topics to be discussed in the next few weeks: • Excessive route update • Routing instability • BGP policy issues • BGP route slow convergence problem • Interaction between BGP/IGP and among BGP components • Anti-IP-spoofing with BGP • New EGP proposals
BGP Routing Stability of Popular DestinationsJennifer Rexford, Jia Wang, Zhen Xiao, and Yin Zhang
Some causes of BGP route changes: • Equipment failures. • Policy changes • Intra-domain topology changes • Potential problems caused BGP route changes: • One “event” triggers a long sequence of updates • CPU • Changing paths with traffic can cause congestion • Transient loops • Make it hard to direct (engineer) the traffic
What is the current situation: • A large fraction of prefixes have stable BGP routes • A small fraction of prefixes are responsible for the majority of Internet traffic • Are prefixes receiving a large volume of traffic more or less stable than prefixes receiving a lower volume of traffic? • Intuitively, more traffic can cause more changes • Popular sites have well managed multiple connections to the Internet.
How the study is done? • BGP routes and updates in RouteViews and RIPE NCC are publicly available • This study adds one monitor in the ATT backbone • The anomalies are removed: • Burst updates due to router failure • Redundant advertisements: • Multiple updates for the same route • Withdraw before announce • Updates or events • An event can cause a lot of updates • Routing stability is better reflected by events • How to get events from updates? • Updates spaced close together in time are counted as one event • This may not be accurate.
A small number of prefixes are responsible for most updates events
Update event vs. traffic volume • Most traffic goes to a small number of prefixes
Update event vs. traffic volume • Prefixes responsible for most update events do not receive a lot of traffic
Explanations: • Unstable prefixes tend to be unpopular • Unstable BGP routes make it different for other hosts to reach the destinations. They cannot be popular.
Conclusion: • The majority of the update events are concentrated in a few prefixes that do not receive much traffic • Popular sites almost have no updates • Implications: suppressing updates mostly likely will not cause disruption of the Internet. • Who are the prefixes that cause most of the updates? • How long does the instability last? • Can we do something about it?