Quality Differentiated services provide the end devices(host)
Quality of services ( QoS) is basically a network’s capability to provide quality service to selected network traffic . Basically, the goal of Qos is to provide guarantees on the ability of a network to deliver packets to destination without any error. Quality of services ( QoS) also dealing with others network performance elements such as error time , latency and uptime. Quality of services ( QoS) is controlling networks resources by setting the priorities for some data such as video , audio and files which is widely used on the network .
The main Qos requirements are bandwidth which is represents a data stream bandwidth, reliability which is represents the tolerance for losses in a data stream and delay which is the relative delay between packets and the round trip delay. Currently the this Qos especially apply on network traffic generated for video on demand, IPTV, VoIP, streaming media, videoconferencing and online gamingThe main services that differentiated services is classify the traffic into groups and handles different traffic groups differently. Basically, differentiated services is a multiple service model that can satisfy the most requirements on networks. DiffServ usually used for mission critical applications and to provide end to end qos.Differentiated services components are traffic conditioning, packet classification , packet marking , congestion management and congestion avoidance . Traffic conditioning function is that to make sure the traffic entering the differentiated services domain.
. Packet classification used to classifier the selects pakets based on the packets values in header fields and steers of packets to appropriate marking functionPacket marking to classify the packet based on a specific traffic descriptor . Congestion management use to scheduling and traffic queuing for packets. Congestion avoidance is use to monitor network traffic loads to avoid congestion on network.
Differentiated services is a computer networking architecture that specifies a simple, scalable, managing network and coarse mechanism for classifying . This model is appropriate for aggregate flows. Differentiated services provide the end devices(host) to classify the packet into different Traffic classes. Each of traffic classes will get a different Per-Hop-Behaviour (PHB) at each hop from the source to the destination. Every network device on the path treat packets according to the locally .The good thing of this model is does not require any resource reservation mechanism on end devices (hosts).
Very easy configuration, operation and maintenance and support complex traffic classification and conditioning at the edge.Integrated services is a framework developed by the Internet Engineering Task Force (IETF) to provide quality of service (Qos) on networks. Usually this qos model provide video and sound to reach the receiver without interruption. Integrated services provides services on a per flow basis where a flow is a packet stream with common source address and destination address . This qos model usually used to avoid the receiver any interruption for the video and sound. IntServ routers must maintain per flow state information.With this integrated service, the application will ask the network for a explicit resource reservation per flow.
The network devices will keep track on every flow traversing the nodes checking if there is any new packets belong to an existing flow, if there is enough of network resources available to accepts the packet.By reserving resources on the network for each flow, applications obtain resources guarantees and a predictable behaviour of the network.The scalability of this model is limited by the fact that exists a high resource consumption on network nodes caused by per flow processing and associated state. This integrated services has two key features which is reversed resources and call setup . In reversed resources , a router is supposed to know what amounts of its resources like link capacity and router buffers . In call setup , A session requiring QoS guarantees must first be able to reserve sufficient resources at all network router on its source to destination path to make sure that its end to end QoS requirement is met. This model perfect for managing flows in smaller networks such as home and small office. However, the disadvantages is poor scalability Both Qos model have different characteristics, for example the IntServ model is more focus on sharing the available network resources among the flows requiring resources to the network.
While the differentiated services model is focus in a less granular approach by sharing network resources among a set of previously defined Traffic ClassesDifferentiated services allows scalability across bigger networks. As differentiated services model is much more scalable than IntServ, it works much better in big network deployments. Integrated services works well on small networks because the number of flows and the size of the network is easy to control.
