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Evaluating Potential Routing Evaluating Potential Routing Diversity for Internet Failure Diversity for Internet Failure

RecoveryRecovery

*Chengchen Hu, *Chengchen Hu, ++Kai ChenKai Chen, , ++Yan Chen, *Bin LiuYan Chen, *Bin Liu*Tsinghua University, *Tsinghua University,

++Northwestern UniversityNorthwestern University

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Internet EmergencyEmergencies or disasters can lead to

substantial Internet disruptionEarthquakes, Storms,Terrorist incident: 9.11 event

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Example: Taiwan earthquake incident

Large earthquakes hit Luzon Strait, south of Taiwan on 26 December 2006

Only two of nine cross-sea cables not affected

All cables reported repaired as of February 14, 2007

Long-term network interruption from Asia to USA

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How reliable the Internet is?BGP resilience is limited [Wu, CoNEXT’07]

32% ASes are vulnerable to a single critical customer-provider link cut

93.7% Tier-1 ISP’s single-homed customers are lost due to Tier-1 depeering

Internet is not as reliable as people expected!Our question: can we find more resources to incre

ase the Internet reliability under Internet emergency?

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OutlineBackground and MotivationBasic IdeaSimulation StudyConclusion

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Basic IdeaInternet eXchange Points (IXPs)

Co-location where multiple ASes exchange their trafficParticipant ASes in an IXP may not be connected via BG

PInternet valley-free routing policy

AS relationships: customer-provider, peering, siblingPeering relationship won’t allow one peer to carry the

traffic from the other peer to its providerMentioned in [Wu, CoNEXT’07], without evaluation

How much can we gain from these two potential resources, i.e., IXP and PR?

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DatasetMost complete AS topology

BGP data + P2P traceroute120K AS links with relationshipshttp://aqualab.cs.northwestern.edu/projects/Sidewalk

Ends.html [Chen et al, CoNEXT’09]IXP data

PCH + Peeringdb + Euro-IX (~200 IXPs)3468 participant ASes

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Failure ModelsTier-1 depeering

Cogent and Level3 depeeringTier-1 provider-customer link teardown

Reported in NANOGMixed types of link breakdown

9.11 event, Taiwan Earthquakes,

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Evaluation MetricsRecovery Ratio

# of recovered <src-dst> AS pairs versus total # of affected <src-dst> AS pairs

Path Diversity# of increased link-disjoint AS paths between affected <

src-dst> AS pairsShifted Path

# of link-disjoint AS paths shifted onto a normal link after we use IXP or PR resources

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Results: Tier-1 Depeering36 experiments for 9 Tier-1 ASesRecovery ratio

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Results: Tier-1 DepeeringPath diversity

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Results: Tier-1 DepeeringShifted path

Different # of shifted AS paths for different links In average, 3.75 ~ 17.2 for all experiments

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ConclusionA first work to evaluate potential routing diversity

with the most complete AS map40%-80% of disconnected <Src, Dst> AS pairs can

be recovered via IXP and PRPoint out a new venue for Internet emergency rec

overy

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Thanks, Q&A

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Backup

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Results: Tier-1 provider-customer links teardown

Recovery ratio

Path diversity4.64 for 10 Tier-1 provider-customer links

teardown4.54 for 20 Tier-1 provider-customer links

teardown

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Results: Mixed types of links breakdownFocus on Taiwan earthquake, 9 big victim ASesRecovery ratio

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Results: Mixed types of links breakdownPath diversity