How many bits in the modified IP ToS field does the DiffServ DSCP use to designate the packet's PHB?

The Differentiated Services Code Point (DSCP) utilizes 6 bits from the modified IP Type of Service (ToS) field to designate the Per-Hop Behavior (PHB) for packets. This is significant because the DSCP provides a mechanism for setting and handling Quality of Service (QoS) in network traffic.

By using these 6 bits, DSCP allows for a variety of service levels by classifying packets into different traffic classes, which can then be treated with different forwarding behaviors within the network. This flexibility enables the prioritization of certain types of traffic such as voice or streaming video, ensuring that they receive the necessary resources and bandwidth to maintain performance levels, especially in congested network conditions.

The use of 6 bits permits the specification of up to 64 different DSCP values, facilitating a robust framework for traffic management in modern networks. This is essential for supporting various applications that may have differing requirements in terms of latency, jitter, and bandwidth.