CoS, Class Of Service

CoS, or Class of Service is a common way to manage web traffic in groups such as email, streaming audio and video content, and large documents. After being grouped together, the categories are treated as a class and is assigned it’s own level of priority service. Opposed to the QoS (Quality of Service) traffic management system, Class of Service methods do not guarantee levels of service in the terms of delivery time and bandwidth; it simply offers a best effort. On the contrary, CoS technology is much simpler to maintain and becomes more extendable as a network expands in traffic volume and overall structure. When comparing the two, CoS can be thought of as a medium-tuned method of network traffic control while QoS can be considered as a more finely-tuned method. Three primary CoS methods: 802. 1p Layer 2 Tagging ToS (Type of Service) DiffServ (Differentiated Service) 802 1p Layer 2 Tagging and ToS implement three bits in the layer 2 packet header used to determine levels of priority. Differentiated Services, a new type of protocol, were developed since three bits only allows for minimal sophistication in managing network traffic. DiffServ does much more than managing packets with priority labeling. It actually indicates how given packets are to be forwarded, a process known as the PHP (Per Hop Behavior).