Computer Networks · free preview
Issues in Resource Allocation
A packet-switched network hands out its bandwidth among competing flows, and the handoff splits into two jobs, congestion control, keeping the network from choking when demand exceeds supply, and resource allocation, dividing what is there fairly, which are easily confused with flow control, the separate matter of not flooding a slow receiver, and the design space is taxonomized along three axes, router-centric versus host-centric intelligence, reservations versus feedback, and windows versus rates, while success is measured by throughput and delay in tension, summarized as power, with fairness the quiet second criterion that decides who bears the pain when the network says no.
1. Two Jobs, One Scarce Resource
Two Jobs, One Scarce Resource
2. Not a Routing Problem
Not a Routing Problem
3. A Taxonomy of Responsibility
A Taxonomy of Responsibility
4. Measuring Success
Measuring Success
5. Three kinds of no
A sender's packets are dropped because the destination's receive buffer is full. Which mechanism was supposed to prevent this?
6. Where the smarts live
What distinguishes a host-centric congestion mechanism from a router-centric one?
7. Ask first or adjust later
What separates a reservation-based approach from a feedback-based one?
8. The power curve
What does the power metric, throughput divided by delay, capture about a congestible network?
9. Stability
What does it mean for a congestion control mechanism to be stable?
10. Windows and rates
Why are rate-based controls natural for multimedia reservations while window-based controls suit stream transports?
11. The protected party
Flow control protects the slow receiver, while congestion control protects what?
12. The dividing ratio
What is the classic metric that divides throughput by delay to summarize a congestible network's operating point?
13. The bad regime
What is the name of the catastrophic regime where the network carries packets only to discard most of them downstream, and almost no useful work completes?
14. The asking approach
In which approach does a source declare its needs and get admitted or rejected before it may send any data?
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