What VLAN tagging standard header does IEEE 802.1p modify to identify Ethernet frame priority?

The correct response is based on the function of the IEEE 802.1Q standard, which is specifically designed for VLAN tagging and includes a mechanism for priority tagging through a modified header. IEEE 802.1Q adds a tag to Ethernet frames, allowing the identification of VLAN memberships, which is crucial in networks that separate traffic into different virtual LANs.

Along with VLAN identification, this standard provides the capability for Quality of Service (QoS) by utilizing the 3-bit priority code point (PCP), which allows up to eight levels of priority for traffic. This is essential in environments where certain types of data, such as voice over IP (VoIP), may need to be prioritized over less time-sensitive data. In this way, the header modification of the Ethernet frame done by IEEE 802.1Q is fundamental for both traffic segmentation and management in network communications.

The other standards listed do not pertain to VLAN tagging or priority management in the same way. For example, IEEE 802.1X relates to port-based network access control, which involves authentication. IEEE 802.1D focuses on spanning tree protocols for loop prevention in network topologies. Lastly, IEEE 802.3ad deals with link aggregation for combining multiple