Trafficaware InterDomain Routing for Improved Internet Routing Stability

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Traffic-aware Inter-Domain Routing for Improved
Internet Routing Stability

• Zhenhai Duan
• Florida State University

2
Outline

• Introduction and Background
• Motivation and Intuition
• Traffic-Aware Inter-Domain Routing (TIDR)
• Performance Studies
• Summary

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Introduction and Background

• Internet consists of large number of network
  domains
• Or Autonomous Systems (ASes)
• Currently about 26K
• Exchange network prefix reachability information
  using BGP
• In a system this big, things happen all the time
• Fiber cuts, equipment outages, operator errors
• Direct consequence on routing system
• Large number of BGP updates exchanged between
  ASes
• Re-computing/propagating best routes
• Events may propagated through entire Internet
• Effects on user-perceived network performance
• Long network delay, packet loss, even loss of
  network connectivity

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Introduction and Background

• Implicit design assumption in BGP
• Failure events of same importance to all users
• No explicit mechanisms to localize failure in BGP
• Internet global reachability global
  propagation of failure
• Is this valid?
• A user (AS) in US may not be interested in
  failure in Asian country
• Design of BGP failed to recognize two Internet
  properties
• Internet access non-uniformity
• Prevalence of transient failures

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Motivation and Intuition

• Internet access non-uniformity
• APRANET(1970, Kleinrok and Naylor)
• Top 12.6 responsible for 90 of traffic
• NSFNET(1980,Rekhter and Chinoy)
• Top 10 responsible for 85 of traffic
• Fang and Peterson (1999), and Rexford(2002)
• Non-uniform distribution nature of Internet
  traffic
• Model on network value IEEE/SPECTRUM2006
• Zipfs law

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Internet Access Non-Uniformity

• FSU Study
• Study if Internet access locality holds from
  viewpoint of edge network
• Bidirectional data traffic collected at border
  router at FSU for 16 days

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FSU Data Traffic on other Days
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BGP Updates (RouteViews Project)
Most of updates are from rest of the prefixes
Only a few updates are related to top prefixes at
FSU
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Motivation and Intuition

• Prevalence of transient failures
• Sprint backbone measurement (2002)
• BGP misconfigurations
• 50 misconfigurations lasted less than 10 minutes

• 50 lt 1 minute
• 80 lt 10 minutes
• 90 lt 20 minutes

Majority of network failures are transient
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Motivation and Intuition
TIDR
Prevalence of Transient Failure Majority of the
network failures on the Internet are transient
Internet Access Non-Uniformity Users
(networks) normally communicates with small set
of other network domains
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Traffic-aware Inter-Domain Routing (TIDR)

• Prefix classified into either significant or
  insignificant
• At AS v, with respect to neighbor n
• Treat differently propagation of sign/insign
  prefixes
• Propagating BGP updates of sign prefixes with
  high priority
• Aggressively slow down propagation of BGP updates
  of insign prefixes
• Localizing effect of transient failures on insign
  prefixes
• Hold propagation of transient failures if valid
  alternative route exists
• BGP withdrawals always propagated

n
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TIDR Timers
Recovery
AS
10 MIN.
15/30 SEC.
TIDR TIMER
MRAI TIMER
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TIDR Design

• How to avoid traffic black-holes?
• If the alternative route that is held by Timer is
  invalid, node will be the black-hole that drops
  all the packets that it receives
• Utilizing Root Cause Information (RCI)
• Similar to EPIC and RCN
• flush out all local invalid alternative routes
• Alternative route chosen can be guaranteed to be
  valid
• How to avoid slow propagation of long-term
  failure of insign pref
• Every node will hold propagation of BGP update,
  if not design carefully
• Only one node will apply TIDR timer to insign
  prefixes
• Nodes neighboring to failure
• First node to have valid alternative route

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TIDR Algorithm
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Performance Studies

• Used simBGP simulator
• With both clique and Waxman random network
  topologies
• Simulated both link fail-down and fail-over
  events
• Only dummy node announce prefixes
• 20 to be significant, 80 to be insignificant
• Link failure
• 20 to be long-term, 80 to be transient
• Settings
• Link delay randomly from 0.01 to 0.1 seconds
• Processing delay randomly from 0.001 to 0.01
  seconds
• MRAI timer 30 seconds
• TIDR timer 10 minutes

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Fail-down Events
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Fail-Over Events
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Summary and On-going Work

• TIDR Traffic-aware Inter-Domain Routing
• Capitalizing on two important properties
• Internet access non-uniformity
• Prevalence of transient failure
• Differentiated BGP update propagation for sign
  and insign prefixes
• Propagating updates of sign prefixes with higher
  priority
• Aggressively slow down propagation of updates of
  insign prefix
• Performed simulation studies
• Outperforms BGP and other existing enhancements