BGP Routing Stability of Popular Destinations Jennifer Rexford, Jia Wang, Zhen Xiao, and Yin Zhang

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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

2
BGP Routing Stability of Popular
DestinationsJennifer Rexford, Jia Wang, Zhen
Xiao, and Yin Zhang
3

• 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

4

• 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.

5

• 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.

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• Grouping events 45seconds/75seconds

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• Event duration mostly lt 5 mins

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• A small number of prefixes are responsible for
  most updates events

9

• Update event vs. traffic volume
• Most traffic goes to a small number of prefixes

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• Update event vs. traffic volume
• Prefixes responsible for most update events do
  not receive a lot of traffic

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• Explanations
• Unstable prefixes tend to be unpopular
• Unstable BGP routes make it different for other
  hosts to reach the destinations. They cannot be
  popular.

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• Popular prefixes do not experience many events

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• Top websites cause very few update events

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• 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?