ZyXEL Communications Prestige 2000W, User Manual, Page: 76 / 81

Prestige 2000W User’s Guide
Administrator-specific Settings 12-7
Table 12-4 System
LABEL DESCRIPTION
RESTART Click this button to restart the Prestige and have your configuration changes take
affect.
SAVE Click this button to save your changes without restarting the Prestige. Your
wireless LAN, Internet and SIP settings changes do not take affect until you use
RESTART.
12.5 Quality of Service
Quality of Service refers to both a network's ability to deliver data with minimum delay, and the networking methods
used to provide bandwidth for real-time multimedia applications. Network traffic can be classified by setting the TOS
(Type Of Service) values at the data source (for example, at the Prestige) so a server can decide the best method of
delivery i.e. least cost, fastest route etc.
12.6 TOS
The second byte in an IPv4 packet is the Type of Service (ToS) byte. The first three bits (by themselves) of the ToS byte
are referred to as the IP Precedence bits and refer to a priority from 0 to 7. The next three bits are used in conjunction
with the IP Precedence bits to define the Diffserv Code Point protocol (DSCP bits). The last two bits are reserved for
future use.
12.7 Introduction to DiffServ
Quality of Service (QOS) mechanisms provides the best service on a per-flow guarantee. To fine-tune the levels of
services on the priority of the traffic flow using QoS places a heavy burden on the network infrastructure.
DiffServ is a class of service (CoS) model that marks packets so that they receive specific per-hope treatment at
DiffServ-compliant network devices along the route based on the application types and traffic flow. Packets are marked
with DiffServ Code Points (DSCPs) indicating the level of service desired. This allows the intermediary
DiffServ-compliant network devices to handle the packets differently depending on the code points without the need to
negotiate paths or remember state information for every flow. In addition, applications do not have to request a
particular service or give advanced notice of where the traffic is going.