| Platform SDK: Quality of Service |
To facilitate explanation, Windows 2000 Quality of Service (QOS) documentation divides its QOS components into three categories:
This division is purely for the sake of convenience and clarity. Though each of these QOS components is in some way initiated at the client or end-node, and in pure semantics, is initiated by the application, the impact of the component may actually be greatest elsewhere.
For an example (which may be clearer once the 802.1p QOS component is further explained), the 802.1p precedence bits are actually set in the end-node's network stack. This is done because it was an application-initiated sequence of QOS events that eventually triggered the setting of the bits. The cause of this bit-setting, then, could be argued to be the application's initiation of QOS service (thus application-driven). However, because the effect of setting the priority on 802.1p bits has the greatest impact when the packets associated with this session cross their local segment, 802.1p is included in the Network-Driven QOS Components category, but not in the Application-Driven QOS Components category. Despite the fact that no QOS requests would have been instigated to set the 802.1p bit without the application's invocation of a QOS component, its explanation is best placed in a discussion of network-driven components. The ripple-effect of 802.1p bit setting, then, is felt greatest in the network.
Although individual components from among the three categories can function independently at times to provide subsets of QOS functionality, Windows 2000 QOS overall is an integrated technology.
The following figure provides a visual representation of the structure of QOS documentation, and the reasoning behind its structure; certain QOS components have greatest impact in one of the three categories, and are thus discussed there.