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排队规则
路由器的队列是拥塞变得可见的地方，而清空队列的规则决定了谁会受损：先进先出加尾部丢弃是简单的默认做法，它会让一个贪婪的流攫取其所能获得的任何份额；优先级队列让被标记的流量插队，但存在饿死未标记流量的风险；而公平队列则将每个流隔离在各自的队列中，通过给每个分组盖上其在理想逐比特轮转下完成的时间戳、并优先服务最小时间戳的方式来近似该理想轮转——这一公式可通过加权扩展为加权公平队列，从而保护表现良好的流免受其他流的影响。
1. The Default and Its Blindness
The Default and Its Blindness
2. Bit-by-Bit, Approximately
Bit-by-Bit, Approximately
3. Weights and What Fairness Buys
Weights and What Fairness Buys
4. When Queues Meet Windows
When Queues Meet Windows
5. The separable pair
A router runs FIFO with tail drop. Which statement about its two components is correct?
6. The starving queues
Why is priority queuing dangerous without admission control or pricing?
7. Packet-size unfairness
Two flows share a link under simple packet-by-packet round-robin. One sends 1000-byte packets, the other 500-byte packets. What happens?
8. The finish-time rule
In fair queuing's approximation of bit-by-bit round-robin, a packet arrives at tick 10 for a flow whose previous packet finished at tick 14, and the packet is 3 bits long. What is its finish time?
9. Isolation
A source floods the link far beyond its fair share. Under fair queuing, who suffers?
10. Weights
Under weighted fair queuing, flow A has weight 2 and flow B has weight 1, and both are backlogged. What share does A receive?
11. The tail's fate
What drop policy discards any packet that arrives to find the buffer full?
12. The idealized service
Fair queuing approximates which impossible ideal, in which the router would interleave one bit from each active flow in turn?
13. The smallest stamp
Under fair queuing, the router next transmits the queued packet with the smallest what?
14. The policy knob
What per-flow parameter does weighted fair queuing add so shares can be proportional rather than equal?