with the growing number of network applications, local area networks (lans) must deliver data for a wide variety applications. email, file transfers, database queries, voice over ip (voip), video-conferencing and multimedia must all be delivered to the end-user's. some of the traffic, such as video-conferencing, is of a higher priority, with a slight delay of packets resulting in noticeable degeneration of video and audio quality, while other traffic, such as email will not be noticeably affected by tiny delays. the large number of programs run over today's networks serves to impede the ability to deliver time-critical data. even if bandwidth is not usually a problem on your network, during peak hours bursts in network traffic can result in the delay of time-critical traffic.

    ieee802.1p defines seven levels of prioritization for ethernet packets. high priority packets will be sent through a network using 801.2p-compliant switches first. lower priority packets will be transferred whenever bandwidth is available. when properly setup, this ensures that time-critical data arrives on time and is not affected by other traffic.