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NANOG Meeting Presentation Abstract

Controlling the Impact of BGP Policy Changes on IP Traffic
Meeting: NANOG25
Date / Time: 2002-06-10 2:30pm - 3:15pm
Room: Grand York Ballroom
Presenters: Speakers:
Nick Feamster, MIT.
Jennifer Rexford, AT&T Labs.
Jay Borkenhagen, AT&T Labs.
Abstract: The Internet consists of about 13,000 autonomous systems (AS\'s) that exchange routing information using the Border Gateway Protocol (BGP). Network operators must have control over the flow of traffic into, out of, and across their networks. However, BGP does not facilitate common traffic engineering tasks, such as balancing load across multiple links to a neighboring AS or directing traffic to a different neighbor.



Solving these problems is difficult because:

  • The number of possible changes to routing policies is too large to exhaustively test all possibilities



  • Some changes in routing policy can have an unpredictable effect on the flow of traffic, and



  • The BGP decision process implemented by router vendors limits an operator\'s control over path selection.





We use empirical analysis of routing tables and traffic measurements from the AT&T backbone to derive operational guidelines for using BGP policy to perform traffic engineering tasks, such as shifting traffic away from a congested peering link. We show that a network operator can manipulate traffic efficiently by changing the routes for the small fraction of destination prefixes (and sets of related prefixes) responsible for the majority of traffic. We show how certain BGP policy changes can move traffic in a predictable fashion, despite limited knowledge about about the routing policies in neighboring domains.
Finally, we show how operators can gain greater flexibility for traffic engineering by relaxing some steps in the BGP decision process (such as the use of AS path length) and ensuring that neighboring AS\'s send consistent advertisements at each peering location. These results enable network operators to use existing BGP features, such as BGP import policies, to accomplish common traffic engineering tasks.



An outline of the talk follows:

  1. Introduction

  2. BGP Traffic Engineering

    1. Border Gateway Protocol

    2. Tools for network-wide traffic engineering



  3. Data Collection

    • BGP routing tables

    • Flow-Level traffic measurements



  4. Overhead of routing changes

    • Simpler import policies: groups of related prefixes

    • Fewer routing changes: popular destinations



  5. Predictability of traffic flows

    • More stable traffic volumes: large traffic aggregates

    • Inbound traffic: limit globally visible changes

    • Tolerating routing changes: limit sensitivity to AS path



  6. Influence of neighboring domains

    • Ensuring consistent advertisements from neighbor AS\'s

    • Limiting the influence of AS path length

  7. Conclusion




A full draft of our writeup is available from:



http://nms.lcs.mit.edu/~feamster/papers/paper-nanog.pdf
Files: youtubeControlling the Impact of BGP Policy Changes on IP Traffic
Sponsors: None.

Back to NANOG25 agenda.

NANOG25 Abstracts

  • Panel: Smart Routing Technologies
    Moderators:
    Sue HaresNextHop; .
    Panelists:
    Jeremy JohnsonnetVmg; .
    Aaron BrittOpnix; .
    Robert BaysProficient; .
    Mike LloydRouteScience; .
    Daniel GoldingSockeye; .
    Brandon RossSockeye; .
  • Panel: Smart Routing Technologies
    Moderators:
    Sue HaresNextHop; .
    Panelists:
    Jeremy JohnsonnetVmg; .
    Aaron BrittOpnix; .
    Robert BaysProficient; .
    Mike LloydRouteScience; .
    Daniel GoldingSockeye; .
    Brandon RossSockeye; .
  • Panel: Smart Routing Technologies
    Moderators:
    Sue HaresNextHop; .
    Panelists:
    Jeremy JohnsonnetVmg; .
    Aaron BrittOpnix; .
    Robert BaysProficient; .
    Mike LloydRouteScience; .
    Daniel GoldingSockeye; .
    Brandon RossSockeye; .
  • Panel: Smart Routing Technologies
    Moderators:
    Sue HaresNextHop; .
    Panelists:
    Jeremy JohnsonnetVmg; .
    Aaron BrittOpnix; .
    Robert BaysProficient; .
    Mike LloydRouteScience; .
    Daniel GoldingSockeye; .
    Brandon RossSockeye; .
  • Panel: Smart Routing Technologies
    Moderators:
    Sue HaresNextHop; .
    Panelists:
    Jeremy JohnsonnetVmg; .
    Aaron BrittOpnix; .
    Robert BaysProficient; .
    Mike LloydRouteScience; .
    Daniel GoldingSockeye; .
    Brandon RossSockeye; .
  • Panel: Smart Routing Technologies
    Moderators:
    Sue HaresNextHop; .
    Panelists:
    Jeremy JohnsonnetVmg; .
    Aaron BrittOpnix; .
    Robert BaysProficient; .
    Mike LloydRouteScience; .
    Daniel GoldingSockeye; .
    Brandon RossSockeye; .
  • Panel: Smart Routing Technologies
    Moderators:
    Sue HaresNextHop; .
    Panelists:
    Jeremy JohnsonnetVmg; .
    Aaron BrittOpnix; .
    Robert BaysProficient; .
    Mike LloydRouteScience; .
    Daniel GoldingSockeye; .
    Brandon RossSockeye; .

 

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