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Quality of Service

Engineering head-end bandwidth explicitly rather than buying more of it — weighted random early detection, class-based weighted fair queuing and policing.

Also known as QoS, Traffic Engineering, WRED, CBWFQ

Left to right is time. Each row is one of the 3 disciplines this one worked alongside, ordered so kindred disciplines sit next to each other rather than alphabetically — a landscape only means anything if neighboring rows belong together. Height is the work running in that domain in that year, weighted by what failure would have cost — life-safety ×3, a statutory obligation ×2.2, the estate itself ×1.5, an evaluation ×1. Every project declares which of those it was, so each ridge traces to an entry you can open and disagree with. Only the work that used this technology is counted, so what shows here is the company it kept rather than the record around it. Height and color are on the record-wide scale rather than this page’s own, so a modest estate draws a modest landscape and any two of these pages can be read against each other.

Where a head end aggregates many branch circuits, the constraint is not the branch link but the point everything converges on. Quality of service is what decides which traffic degrades first when that point saturates, and leaving it to default is a decision too — usually the wrong one, made by whichever application is most aggressive.

Weighted random early detection to signal congestion before the queue is full rather than after, class-based weighted fair queuing to hold a floor under the traffic that cannot absorb loss, and policing at the edge so one site cannot consume the aggregate. On an estate carrying voice badges and public access on the same plant, the classification decision is a service decision rather than a technical preference.

Applied in

  • Enterprise Core Network2005–2024The city's core network across nineteen years — architecture, standards and, when it mattered, hands on the equipment.
  • Jacksonville Public Library Network2005–2023Eighteen years and two full redesigns of a central library and its branches, from the Main Library's opening to the carrier handoff.
  • Cisco DOCSIS Residential Cable Buildouts2000–2008Greenfield residential cable plant, headend policy, address management and voice — and one public address pool carrying thousands of residents.

See also

Also searched as

  • QoS
  • traffic engineering
  • congestion management
  • latency optimization