Editing Differentiated services (section)

==Traffic management mechanisms==
DiffServ is a ''coarse-grained'', ''class-based'' mechanism for traffic management. In contrast, IntServ is a ''fine-grained'', ''flow-based'' mechanism. DiffServ relies on a mechanism to ''classify'' and ''mark'' packets as belonging to a specific class.  DiffServ-aware routers implement [[per-hop behavior]]s (PHBs), which define the packet-forwarding properties associated with a class of traffic.  Different PHBs may be defined to offer, for example, [[Packet loss|low-loss]] or [[Network delay|low-latency]] service.

Rather than differentiating network traffic based on the requirements of an individual flow, DiffServ operates on the principle of [[traffic classification]], placing each data packet into one of a limited number of traffic classes. Each router on the network is then configured to differentiate traffic based on its class. Each traffic class can be managed differently, ensuring preferential treatment for higher-priority traffic on the network. The premise of Diffserv is that complicated functions such as packet classification and policing can be carried out at the edge of the network by edge routers. Since no classification and policing is required in the core routers, functionality there can then be kept simple. Core routers simply apply PHB treatment to packets based on their markings. PHB treatment is achieved by core routers using a combination of scheduling policy and queue management policy.

A group of routers that implement common, administratively defined DiffServ policies are referred to as a ''DiffServ domain''.<ref>{{citation |url=http://enterprise.huawei.com/ilink/enenterprise/download/HW_134362 |title=S3700HI Ethernet Switches Configuration Guide - QoS |page=7 |publisher=[[Huawei]] |access-date=2016-10-07 |quote=A DiffServ domain is composed of a group of interconnected DiffServ nodes that use the same service policy and PHBs.}}</ref>

While DiffServ does recommend a standardized set of traffic classes,{{Ref RFC|4594}} the DiffServ architecture does not incorporate predetermined judgments of what types of traffic should be given priority treatment.  DiffServ simply provides a framework to allow classification and differentiated treatment. The standard traffic classes (discussed below) serve to simplify interoperability between different networks and different vendors' equipment.