Load balancing in OSPF
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This document discusses OSPF, load balancing, and ECMP. It begins with an overview of OSPF as an intra-AS routing protocol that uses the Dijkstra algorithm to find the shortest path. It then discusses the load balancing problem and how ECMP can provide a solution by equally splitting traffic across multiple equal-cost paths. The benefits of ECMP include load balancing, improved bandwidth utilization, and congestion mitigation. Traditional ECMP has drawbacks, but weighted ECMP can optimize end-to-end delay by distributing traffic based on pre-determined weight ratios.
Load balancing in OSPF
- 1. OSPF Load Balancing Sharif University of Technology Department of Computer Engineering Winter 2016 By: Arash Pourdamghani
- 2. Arash PourdamghaniWinter 2016 Update: OpenSignal’s New Report 2 November 2016 Iran
- 3. Arash PourdamghaniWinter 2016 Review of OSPF Stands for Open Shortest Path First Inside Autonomous Systems(Intra-AS) Local Link-State(Dijkstra) algorithm in order to find shortest path Version 2 -> IPv4 , Version 3 -> IPv6 3
- 4. Arash PourdamghaniWinter 2016 Load Balancing Problem Optimize Networking! Layaer-4 switching NAT-like function 4
- 5. Arash PourdamghaniWinter 2016 Solution: ECMP Equal-Cost Multiple Routes Equally split traffic over multiple paths ECMP is available only for Linux in UNIX world 5 http://www.cs.princeton.edu/courses/archive/spring11/cos461/
- 6. Arash PourdamghaniWinter 2016 Benefits of ECMP Load balancing Improve bandwidth utilization Mitigate congestion 6
- 7. Arash PourdamghaniWinter 2016 Source DAG Each Router has set of next hops 7 http://courses.cs.washington.edu/courses/csep561/13au
- 8. Arash PourdamghaniWinter 2016 ECMP Forwarding Random Allocation Round-Robin Hash-Threshold Information Random! Per-packet Header based Balanced Complete Near-Optimal Partial Disruption High High Low TCP-Friendly No No Yes 8
- 9. Arash PourdamghaniWinter 2016 Traditional ECMP drawback 9 Link capacity = 1
- 10. Arash PourdamghaniWinter 2016 Weighted ECMP Optimize end-to-end delay Distributes based pre-determined ratios Use heuristic algorithm Obtain the near-optimal weight configuration 10
- 11. Arash PourdamghaniWinter 2016 Weighted ECMP advantage 11
- 12. Arash PourdamghaniWinter 2016 References J. Moy, (April 1998). "OSPF Version 2". The Internet Society. OSPFv2. Retrieved 2007-09-28. J. Kurose, K. Ross, “Computer Network Top-Down Approach”,6th edition, Pearson Education Inc., 2013 A. Tanenbaum, D. Wetherall, “Computer Networks”, 5th edition, Pearson Education Inc., 2011 12
- 13. Arash PourdamghaniWinter 2016 References(cont’d) C. Hopps, “Analysis of an Equal-Cost Multi-Path Algorithm(RFC 2992), The Internet Society”, 2000 J. Zhang, K. Xi, L. Zhang , “Optimizing Network Performance using Weighted Multipath Routing”, NYU Tandon School of Engineering 13
- 14. Arash PourdamghaniWinter 2016 Thank You 14
Editor's Notes
- #3: 3 meg be 11 meg Coverage 52 be 47 !!
- #4: توی کتاب صرفا به ورژن ۲ اشاره کرده
- #5: -NAT-like function, translating the public external IP address to the internal IP address of the appropriate host -Optimize resource use, throughput, response time and overload of any single resource
- #8: Extended Dijkstra
- #9: Disruption is the measurement of how many flows have their paths changed due to some change in the router.
- #10: Link capacity = 1
- #11: overloading or underutilizing some links
- #12: The results indicate Weighted ECMP reduces the end-to-end delay of most pairs in the network