COS and QOS

Quality of Service (QoS)
 
1: on the Internet or other networks, Quality of Service (QoS) indicates that the transmission rate, error rate, and other characteristics of the network can be measured and improved, and to some extent, advance assurance. QoS of the networks that transmit video and multimedia information is particularly concerned.
 
With the Internet Resource Reservation Protocol (RSVP), packets can be accelerated when they pass through the host based on policies and predefined reserved standards. Using ATM allows companies or users to select quality standards of service terms in advance. QoS can be measured and guaranteed based on the average latency of one channel, that is, the delay changes, cell loss rate and transmission error rate of a group of cells (cell is a 53-byte transmission unit. Common Open Policy Service (COPS) is a relatively new protocol that allows routers or layer-3 switches to obtain QoS policy information from Network-Layer servers.
 
2. Class of Service (CoS)
 
Class of Service (CoS) is a way to manage the same network path using similar clustering methods (such as e-mail, data streaming video, voice, large file processing and conversion ). Each category has its own level and priority. Unlike Quality of Service (QoS) path management, Service types cannot guarantee bandwidth and time-related Service levels. They provide the most effective way. In addition, CoS technology is easier to control and upgrade when the network structure is complex and traffic increases. We can regard CoS technology as rough control, while QoS as precise path control. Generally, there are three main CoS technologies: 802.1 p Layer 2 tag technology, type management (ToS), and difference service (DiffServ ).
 
 
 
To put it simply, COS is a mechanism that allows data to enjoy different benefits and is part of the service quality control standard.
 
What benefits does it bring to customers?
 
CoS assigns different transmission statuses to each application, so that data transmission with different priorities is treated differently. For example, for key data applications that require rapid response, such as data transaction processing, video or voice transmission, CoS will assign a "Highest Level" priority tag, coS is assigned a low-level tag for time-insensitive data applications, such as E-mail or Web surfing. According to the priorities set by enterprise users, data can be transmitted to all parts of the world, which of course cannot be guaranteed by service providers. CoS technology is now supported by major network equipment companies, such as Cisco and 3Com.
 
So what is the difference between Cos and Qos?
 
CoS and QoS are different: QoS is divided into service levels based on bandwidth or transmission time (such as bandwidth priority or Traffic Shaping), while CoS is the transport priority of traffic. The IP-based frame relay and ATM networks allow users to fully utilize the benefits brought by QoS and CoS technologies. With CoS, you can achieve end-to-end priority allocation and transmission across the network. For a private network, because the service provider owns the entire network, the priority of the entire network can be guaranteed.
 
CoS works as follows: first, in each connected terminal, CoS sets the differentiated service Diff-Serv code for each IP Data grouping header based on the needs of various applications, that is, set the priority for the Data Group. The management of network data is completed by users. Diff-Serv is only a protocol used to prioritize data. Based on the user's network, IP groups with different priorities are encapsulated into frame relay or ATM cells and transmitted over the user's network. Data passes through the user's network and arrives at the entry switch, where frame relay or ATM cells are unblocked as downstream IP groups. The entry switch measures downstream data traffic based on user traffic requirements, and assembles these data groups in an appropriate order based on the priority of different traffic types. Then, the data is encapsulated in the Multi-Protocol Label Switching MPLS group and transmitted in the core network running MPLS. Vswitches in the core network can guarantee the data priority service and finally send the data to the egress switch. The egress switch then unpacks the MPLS group into an IP group. At the user's exit interface, the IP Group is re-adjusted according to the initial order and then encapsulated into frame relay or ATM cells. The cells are finally transmitted to the user's device through the loop. The User device switches the group to IP data and sends the data based on their priority.
 
In short, CoS is a technology that can improve network and business efficiency for enterprises that need to classify data, voice and video priorities to achieve more reliable and high-performance data transmission.