Chapter 17

Packet Queueing and Scheduling

We dance round in a ring and suppose,

But the Secret sits in the middle and knows.

Robert Frost


A critical function of a router is to handle queueing of arriving packets and then schedule them on an outgoing interface. This is essentially the job of the “queue manager” at a router. An important requirement is that these functions need to be efficient so that a packet leaves a router extremely quickly while giving priority to certain packet types as and when needed. In this chapter, we discuss queueing disciplines a router might employ for scheduling packets and measures for dropping them.


packet scheduling; weighted round robin (WRR); weighted fair queueing (WFQ); ...

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