Cisco QOS Exam Certification Guide (IP Telephony Self-Study), Second Edition

Introduction

Computing in general, and networking in particular, must deal with the issues relating to constrained resources. For computers, operating systems must find a way to equitably distribute the CPU time and memory among the various programs running on the computer. When the need for memory exceeds the available memory, the CPU spends more time performing memory management, moving data from memory to permanent storage, typically on a hard disk. Of course, the computer might be low on CPU resources at the same time, meaning the CPU has less available time to devote to overhead tasks like memory management. With only a small load on the computer, all is well. When the load exceeds the capacity of the CPU, memory, and other resources, a ...