Class of Service

What Does Class of Service Mean?

Class of Service (CoS) is a term that describes the process of managing different kinds of data traffic in the network in different ways. Professionals may talk about giving each type of data it’s own “service priority” or “bandwidth” within the system.


Techopedia Explains Class of Service

In order to achieve this kind of prioritization, systems may use specific tools such as 802.1 layer 2 tagging, type of service (TOS) indicators, or differentiated services resources. One example is that by using layer 2 of the OSI model, systems can evaluate packets and assign them a class of service that determines how that data is treated in the network. For example, a network might treat voice data differently than informational data, in order to preserve crystal-clear voice connections. Or, with data transmission, formats like image and video may be treated differently than text or alphanumerical data. It is all part of sophisticated network administration, and allocating resources for different types of data transmissions.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.