Optimizing AS Paths
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Transcript of Optimizing AS Paths
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Nick Kephart, Sr. Director of Product Marketing
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• May 5th 2016• Intro to Autonomous Systems, the BGP protocol and
how routes are advertised and learned
BGP Webinar Series
• June 16th 2016• How to visualize, diagnose and set alerts to detect
BGP hijacks and leaks
How BGP Works
Detecting Hijacks & Leaks
• May 24th 2016• Explore data from routing change events and learn
how to detect BGP changes with alerts
Monitoring Route Changes
Optimizing AS Paths
• July 28th 2016• Tips and tricks for using routing data to improve how
traffic flows into or out of your network
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About ThousandEyesThousandEyes delivers visibility into every network your organization relies on.
Founded by network experts; strong
investor backing
Relied on for critical operations by leading enterprises
Recognized as an innovative
new approach
30 Fortune 5005 top 5 SaaS Companies
4 top 6 US Banks
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• Generally prefers the shortest AS Path
• Generally trusted advertisements
• Has quick convergence across the Internet
• Follows the route of the most specific prefix
BGP Strengths and Limitations
• It’s often not the most performant
• Hijacks and leaks, even from trusted sources
• Flapping and route instability
• Many covered prefixes not finely tuned
BGP… Yet…
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When BGP Delivers Suboptimal Results
• Developing country connections
• Peering at remote IXs
• Underlying capacity issues
Examples
Two sources in Taiwan, one target in Taiwan,
one path via the U.S. (+150ms)
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Common, Perhaps Suboptimal, Peering Points
MiamiLos Angeles
San Jose
FrankfurtLondonAmsterdam
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1. Monitor the layer 3 path2. Monitor both forward and reverse paths3. Evaluate your peering policies4. Layer covering and covered prefixes5. Prepending, MED and advertisements6. Consider Anycast where appropriate
Optimizing AS Paths
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• Map actual traffic paths to BGP routes
• Understand loss and latency of the path
• Does the path double-back across the Pacific? Peer in Frankfurt?
Monitor the Layer 3 Path
Optimizing BGP #1:
Intra-Asia traffic peering in LAX
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• See how asymmetric routing impacts performance
• Decompose loss and latency in each direction
• Agent-to-Agent tests for reverse path; Private BGP Monitors for reverse routes
Monitor Both Forward & Reverse Path
Optimizing BGP #2:EWRàLON via ZayoEWRßLON via Telia
DFWàLON via TeliaDFWßLON via Softlayer
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• Reduce suboptimal routing by increasing peering
• Consider primary ISPs with most/nearest peering connections
• Consider peering with a regional IXP
How Well Do You Peer?
Optimizing BGP #3: Google’s peering
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• Use prefixes to your advantage
• Place backup policies/routes in a covering prefix
• Especially for DDoS mitigation, failover routes
Covered & Covering Prefixes
Optimizing BGP #4:
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• Prepending can make a route less desirable, but can have unintended consequences
• MED can signal which routes your prefer to be be propagated
• Communities can be used to coordinate route propagation with your ISP
Prepending, MED and Communities
Optimizing BGP #5:
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• For some services (even TCP!) Anycast can make sense
• Broadcast routes for the same prefix from multiple origins
• Make sure to validate optimal routes
Consider Anycast
Optimizing BGP #6: J Root:6 origin Autonomous Systems
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Demo
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Two Tales of Taiwan Peering
Target in Taiwan
Verizon peering in Palo Alto
Telia peering in San Jose
Telstra backbone to San Jose
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See what you’re missing.
Watch the webinar
www.thousandeyes.com/webinars/optimizing-as-paths