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ip-backbone

ISP backbone

MPLS backbones

SystemTechniques · 4Primitives · 24 ip-backbone Active queue managementnetworking · medium: RED, CoDel and PIE: drop or ECN-mark early to keep switch and router queues shortFast reroutenetworking · medium: Precomputed loop-free alternates (LFA, TI-LFA) for sub-50 ms failoverLink state routingnetworking · medium: OSPF/IS-IS link-state flooding and SPF route computationTraffic engineeringnetworking · medium: Constrained SPF and centralized path computation to place traffic under capacity limitsFair queuingnetworking · low: Deficit round robin / weighted fair queuing to share capacity among tenants or flowsDijkstra's algorithmgraphs · low: Single-source shortest paths with non-negative edge weights by settling vertices in order of distance with a priority queue.›Bfdnetworking · low: Bidirectional Forwarding Detection: sub-second link/path failure detection with tight hello timersSegment routingnetworking · low: Source routing with segment lists (SR-MPLS, SRv6) for traffic steeringLongest prefix matchnetworking · low: IP prefix lookup structures (DIR-24-8, Poptrie, LC-trie) for routes, ACLs and geo-IPMpls label switchingnetworking · low: MPLS label push/swap/pop forwarding and label distributionSimplex methodoptimization · low: Solves linear programs by walking along the edges of the feasible polytope from vertex to vertex, one basis swap (pivot) at a time; the workhorse behind MIP solvers.›Count-min sketchdata-structures · low: d rows of w counters estimate any item's frequency in a stream, overestimating by at most ε·N with probability 1-δ, in fixed tiny memory.›Max flow (Dinic)graphs · low: Maximum s-t flow by BFS level graphs and blocking flows; also gives the min cut, bipartite matching and assignment with capacities.›Bgpnetworking · low: BGP sessions, UPDATE messages, path attributes and best-path selectionEcmpnetworking · low: Equal-cost multipath: hash flows across next hops; resilient hashing on changesRpki route origin validationnetworking · low: RPKI ROAs and route origin validation to reject hijacked BGP announcementsToken bucketsystems · low: A bucket of up to b tokens refilled at rate r; requests spend tokens, enforcing an average rate while allowing bursts of b.›Packet header parsingnetworking · low: Parse graph state machines for Ethernet, IP, TCP and UDP headers in hardware and softwarePRNGs (PCG, xoshiro)numerics · low: Small, fast, statistically strong non-cryptographic generators: PCG32 and xoshiro256**, with seeding, parallel streams and unbiased ranges.›Exponential smoothing (ETS, Holt-Wi…statistics · low: Forecast by keeping a few running states (level, trend, seasonal) updated by a fraction of each forecast error; O(1) memory per series and a strong baseline.›+ 8 more primitives

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In-house systems

Named systems of this kind at large companies, with their paper or write-up.

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