Internet Routing Instability

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Internet Routing Instability

• OFFENSE
• Scott Crosby Atul Singh

2
Critique

• Poor title
• Level of contribution
• Clarity of presentation
• Correctness
• Methodology
• Claims
• Relevance

3
Poor Title

• Not about stability
• But, its about routing traffic
• Doesnt tell desirable updates from undesirable
  updates
• Better title Characterization of BGP routing
  traffic

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Route updates
Change state
Change nothing
Desirable and Necessary
Undesirable
Topology
Policy
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Contribution

• Measurement results must be clear for this to be
  a contribution
• Most paths are stable
• Already known from Paxon96
• Free debugging
• bad implementations
• vendor screw ups

6
Clarity

• Figure 2
• Only shows 10 of the picture Where is WWDup?
• Appears uncorrected for missing data
• Useless to estimate true distribution
• Cant eyeball ratio of different categories

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(No Transcript)
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Clarity

• Figure 3
• Impressive graph with 30,000 sample points
• Unreadable, unnecessary
• Only discusses trends should graph trends.

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Fig 3 Internet forwarding instability density
measure at Mae-east Exchange point during 1996.
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Correctness

• '99 of routing messages are pathological'?
• No data to backup their claim
• Analysis of routing messages
• Wheres the table of the number of each type?
• Wheres the table estimating the number of
  unnecessary routing messages?

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Methodology

• Only 5 sites, why is that enough?
• Discount private exchanges
• Do the instabilities actually effect performance?
  
• Claim yes, but no evidence
• Ugliness is not a crime
• Uses prefix-pair tuple
• How to deal with aggregation?

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Claims

• routing instability contributes to poor
  end-to-end performance?
• Paxon96 paper shows 1 problems
• high levels of instability can lead to packet
  loss
• Paxon96 shows this is rare
• Unverified

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Relevance

• Does instability matter?
• If the network changes, it changes
• A network with static routes would be perfectly
  stable
• But not robust
• Debug vendor Xs code
• Obsolescent
• new routers contain a full forwarding table in
  RAM
• Care about end-to-end performance

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Its a dirty job to critique but someone had to
do it

• Poor title
• Level of contribution
• Clarity of presentation
• Correctness
• Methodology
• Claims
• Relevance