optimizing as paths

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