QoS Operational Model

Thus far, the discussion has laid out the fundamentals of QoS and the types of roles it can play, and has defined some general terms such as CoS, ToS, and DCSP. This section will explore the various steps necessary for a QoS packet to traverse from a Catalyst 6500 switch's ingress to egress port.

Catalyst QoS operational model consists of five steps:

1.
Classification
2.
Input scheduling
3.
Marking and policing
4.
Marking
5.
Output scheduling

Classification

Classification is the initial step that needs to be discussed. The Catalyst switch needs to distinguish one incoming frame from another so that it can appropriately forward the packet through the switch.

Figure 8-1 depicts the path the frame takes before going to the switching ...

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