DSCP values can be expressed in decimal form or by PHB.
Which PHB is the equivalent of DSCP 20?
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A. B. C. D.B.
Differentiated Services Code Point (DSCP) is a field in the IP packet header that defines the priority level of the packet. Per-Hop Behavior (PHB) is a set of rules that define how routers and switches handle traffic based on the DSCP value.
There are 64 possible values for DSCP. The first 6 bits of the 8-bit DSCP field define the codepoint, and the last 2 bits are unused. DSCP values can be represented in decimal form or in PHB notation.
AF (Assured Forwarding) is a PHB that defines four classes of traffic, each with a different priority level. AF class values are defined in the range of 1 to 4, and within each class, there are three drop precedence levels (low, medium, and high), denoted by the values 1 to 3.
The AF PHB corresponding to DSCP 20 can be found by looking at the DSCP to PHB mapping table. DSCP 20 falls into the AF21 class, which has a drop precedence of 1. Therefore, the answer is option B, AF22, which represents the same AF class with a drop precedence of 2.
To summarize, DSCP 20 maps to the AF21 PHB, and the equivalent PHB notation is AF22.