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Fast network recovery. Amund Kvalbein Post Doc. My place in the world. Simula Public basic research institute About 80 researchers About 25 in Networks and Distributed Systems Myself Leading (small) REPAIR project REPAIR = REsilient Protocols And Ip Routing. Outline.
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Fast network recovery Amund Kvalbein Post Doc
My place in the world • Simula • Public basic research institute • About 80 researchers • About 25 in Networks and Distributed Systems • Myself • Leading (small) REPAIR project • REPAIR = REsilient Protocols And Ip Routing
Outline • What is wrong with todays routing • Current solutions (IPFRR) • (MPLS) • For connectionless, single path routing • Long term solutions • Multipath routing
Todays routing • Single path • Semi-static • Optimized for some TM estimate • Global reaction to failures • Reactive rather than proactive
What is the problem? • Handling unexpected situations is too expensive! • Realtime applications need fast recovery • A global network convergence is too expensive for transient failures • Slow (O(seconds)) • Stability issues
Fast IGP rerouting • Fast proactive rerouting mechanisms developed • Prepares backup paths in advance • Packet forwarding during re-convergence • Can delay triggering re-convergence
Solutions for existing routing protocols (OSPF/IS-IS) • Equal Cost MultiPath (ECMP) • Loop-Free Alternates • Not-Via addresses • Failure-Inference Routing • Multiple Routing Configurations
Multiple Routing Configurations • Relies on multiple logical topologies • Builds backup configurations so that all components are protected • Recovered traffic is routed in the backup configurations • Repairs to the egress node
Multiple Routing Configurations C3 C1 C2
Forwarding C0 C3
Multipath routing • If we have multiple paths to a destination, we also have fast rerouting • Rising interest in multipath routing • Multipath routing algorithms • Intradomain (JJ Garcia-Luna-Aceves) • Interdomain (J Rexford) • Randomized approaches • ”Source routing” (X Yang) • Network slicing (N Feamster)
Adaptive routing • This is an old idea • ARPANET did adaptive routing • Wang/Crowcroft 1992: Adaptive routing gives oscillations • Is this always true?
Summary • Fast recovery needed • Should be local and proactive • Solutions proposed for current routing protocols • Multipath routing could be long-time solution