Optimum Implementation of TI-LFA and Segment Routing on SURFnet 8 - - PowerPoint PPT Presentation

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Optimum Implementation of TI-LFA and Segment Routing on SURFnet 8 - - PowerPoint PPT Presentation

Jan 08, 2024 154 likes •653 views

Optimum Implementation of TI-LFA and Segment Routing on SURFnet 8 RP #22 Peter Prjevara & Fouad Makioui Supervisors: Marijke Kaat & Wouter Huisman The Goals of Networks ARPANET - 1974 2 https://en.wikipedia.org/wiki/ARPANET What

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Optimum Implementation of TI-LFA and Segment Routing on SURFnet 8

RP #22 Peter Prjevara & Fouad Makioui Supervisors: Marijke Kaat & Wouter Huisman

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The Goals of Networks

ARPANET - 1974

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https://en.wikipedia.org/wiki/ARPANET

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What IGPs Currently Offer?

  • Sub-second convergence times (< 1000ms)

○ If effects BGP -> can take up to 3 minutes

  • Reactive Approach

○ Fault Recognition ○ Information Flooding

3 Source: T Anji Kumar and MHM Prasad. Enhanced multiple routing configurations for fast ip network recovery from multiple failures.

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The Goals of Networks Today

  • Real time services

○ VoIP / Video ○ Cloud Software ○ Financial Trading ○ Experimental

Where might virtual reality lead us?

David Ramos/Getty Images

Not good enough

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Network in a Normal State

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Failure Occurs

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The Reactive Approach: Step 1

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The Reactive Approach: Step 2

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Segment Routing (or SPRING)

  • Every node is labelled

○ Node ID

  • Every link is labelled

○ Adjacency ID

  • MPLS labels

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  • IGP to distribute Segment IDs (SIDs) creating a full mesh
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Protective Fast Reroute Solutions

rLFA TI-LFA

5 6 5 5 5 5 100

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Point of Local Repair (PLR) Juniper Networks, 2017. Juniper Tech Library - Fast Reroute Overview.

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Feature Link / Node Protection

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Link Protection

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Node Protection

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Link / Node Protection Summary

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Fate Sharing

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SURFnet8 Topology

  • Interfaces that share the same fate due to:

○ Line card sharing ○ Optical path sharing

  • Juniper Routers used that support:

○ TI-LFA ○ SPRING ○ Node Protection ○ Fate Sharing

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Line card sharing

Optical cable sharing

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Research Questions

  • 1. How do different TI-LFA configurations perform when

implementing Node / Link Protection and Fate Sharing?

  • 2. How do they affect the proposed metrics in IGP?
  • 3. Is fate sharing necessary for all links that share the same

line card or optical layer?

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Methodology

  • Desk research

○ Understand novel concepts

  • Define experiments

○ Create topology

  • Analyse results
  • Draw conclusions

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Our Test Topology

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Our Test Topology

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Our Test Topology

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Our Test Topology

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Experiment Sub Experiment Baseline SR Without TI-LFA With TI-LFA Baseline SR with extra hop Without TI-LFA With TI-LFA Multiple link failures with source as PLR With a single backup path With equal cost multi paths With fate sharing Link/Node Protection Observe the routing table on PLR ECMP Metric Calculation Python Script Simulation / Paper analysis

List of Experiments

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Baseline SR

  • SR without TI-LFA vs SR with TI-LFA

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Baseline SR with Extra Hop

  • SR without TI-LFA vs SR with TI-LFA (without crosslink)

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Results

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Multiple Link Failures 1

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Multiple Link Failures 2

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Multiple Link Failures 3

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Multiple Link Failures 4

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Multiple Backup Paths

Route output

145.125.124.6/32 (2 entries, 1 announced) *L-ISIS Preference: 14 Next hop: 145.125.176.59 via ge-2/3/0.0 weight 0x1, selected Next hop: 145.125.176.18 via xe-2/0/2.0 weight 0xf000 Next hop: 145.125.176.0 via et-1/1/0.0 weight 0xf000

  • Maximum 8 backup paths

○ Equal Cost Multi Path (ECMP)

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Experiment: Fate Sharing

  • TI-LFA with fate sharing

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Results

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Multiple Broken Links

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Average ~500ms

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Multiple Broken Links

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Average ~500ms

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Multiple ECMPs

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Average ~52ms

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Fate Sharing Enabled

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Average ~30ms

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Link | Node Protection

Link protection

145.125.124.6/32 (2 entries, 1 announced) *L-ISIS Preference: 14 Next hop: 145.125.176.59 via ge-2/3/0.0 weight 0x1, selected Next hop: 145.125.176.18 via xe-2/0/2.0 weight 0xf000 Next hop: 145.125.176.0 via et-1/1/0.0 weight 0xf000

Node protection

145.125.124.6/32 (2 entries, 1 announced) *L-ISIS Preference: 14 Next hop: 145.125.176.59 via ge-2/3/0.0 weight 0x1, selected Next hop: 145.125.176.61 via ge-2/3/1.0 weight 0xf000 Age: 51 Metric: 25 40

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Discussion

  • TI-LFA works well with ECMPs, so ECMPs should be

implemented on SURFnet8

  • Node protection effects ECMPs
  • If fate sharing is enabled, routers might not use the post

convergence backup path

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Recommendations

  • Use low metrics on links between core routers

○ Default metric on the daisy chain (default 10) ○ Increase number of ECMPs

  • Implement fate sharing
  • Do not use node protection

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Future Work

  • Improve failure detection speed

○ Bidirectional Forwarding Detection (1 - 10ms)

  • How will SRv6 perform in comparison with SR on MPLS?

○ Currently not implemented yet

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Acknowledgements

  • Special thanks:

○ Marijke Kaat and Wouter Huisman ○ SURFnet Team

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Q & A

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