The diffserv approach to providing QoS in networks employs a small, well-defined set of building blocks from which you can build a variety of(71). Its aim is to define the differentiated services (DS) byte, the Type of Service (ToS) byte from the Internet Protocol Version 4 (72)and the Traffic Class byte from IP Version 6, and mark the standardized DS byte of the packet such that it receives a particular forwarding treatment, or per-hop behavior (PHB), at each network node. The diffserv architecture provides a(73)within which service providers can offer customers a range of network services, each differentiated based on performance. A customer can choose the (74)level needed on a packet-by-packet basis by simply marking the packet's Differentiated Services Code Point (DSCP) field to a specific value.
This  (75) specifies the PHB given to the packet within the service provider network。
(71) A services     B. Users C.networks D. structures
(72) A message    B. Packet C.header D. package
(73) A. information  B. Structure C.means D. framework
(74) A. performance B. Secure C.privacy D. data
(75) A. packet     B value C.service D. Paragraph