The internet can be unpredictable, and this can affect time-sensitive data such as VoIP and streaming media. In IPv4, the TOS field can be used to prioritize traffic so that it is delivered at a higher precedence than email or web pages.

Wireshark presents the TOS field as DiffServ, which is similar to TOS in offering prioritization, but with subtle differences and improvements to handle the real-time protocols in use today:

• DiffServ 8-bit: This field is separated into two functions: Quality of Service (QoS) and Explicit Congestion Notification (ECN).

In frame 1, we can see the Differentiated Services Field: 0X00 (DSCP: CSO, ECN: Not-ECT). Let's step through what this represents. We'll start with the first 6-bit of the DiffServ field, which is used to represent the QoS requested when traveling through a network.