Chapter 5. Quality of Service (QoS)


Voice, video, and data travel side by side over today's converged networks. Some of these traffic types (for example, VoIP) need better treatment (that is, higher priority) than other types of traffic (for example, FTP). Fortunately, Cisco offers a suite of QoS tools for providing special treatment for special traffic.

In the absence of QoS, traffic might suffer from one or more of the following symptoms:

  • Delay (latency)—Excessive time required for a packet to traverse the network
  • Delay variation (jitter)—The uneven arrival of packets, which in the case of VoIP can be interpreted by the listener as dropped voice packets
  • Packet loss—Dropping packets, especially problematic for User Datagram Protocol ...

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