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QOS Overview (summary). Class Map >> Policy Map >> Service Policy AF = Assured Forwarding – basically a guideline for marking traffic EF = Expedited Forwarding – only 40 or 46. Example: AF 1 2 First value is Class Selector Second value is Drop Probability.
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QOS Overview (summary) Class Map >> Policy Map >> Service Policy AF = Assured Forwarding – basically a guideline for marking traffic EF = Expedited Forwarding – only 40 or 46 Example: AF 12 First value is Class Selector Second value is Drop Probability TOS (Type of Service) – field is 8 bits in IP header DSCP – Differentiated Services Code Pointer DSCP only uses 6 of the 8 bits within TOS field First 3 bits = Class Selector Next 2 bits = Drop Probability Last 1 bit = Reserved Class Selector 0 0 1 – Worst Class 0 1 0 0 1 1 1 0 0 – Best Class C C C D D R X X 0 0 0 0 0 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 0 0 1 0 1 0 0 1 1 0 Drop Probability 0 1 - Low 1 0 - Medium 1 1 - High AF Bits 0 0 0 1 1 0 Worst Best EF (voice) AF11 - Low AF12 - Med AF13 - High AF21 - Low AF22 - Med AF23 - High AF31 - Low AF32 - Med AF33 - High AF41 - Low AF42 - Med AF43 - High Service Bits