2 what you need to know, 3 the quality of service general screen – ZyXEL Communications Prestige P-870HW-51a v2 User Manual
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Chapter 11 Quality of Service (QoS)
P-870HW-51a v2 User’s Guide
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11.2 What You Need to Know
The following terms and concepts may help as you read through this chapter.
QoS versus Cos
QoS is used to prioritize source-to-destination traffic flows. All packets in the same
flow are given the same priority. CoS (class of service) is a way of managing traffic
in a network by grouping similar types of traffic together and treating each type as
a class. You can use CoS to give different priorities to different packet types.
CoS technologies include IEEE 802.1p layer 2 tagging and DiffServ (Differentiated
Services or DS). IEEE 802.1p tagging makes use of three bits in the packet
header, while DiffServ is a new protocol and defines a new DS field, which replaces
the eight-bit ToS (Type of Service) field in the IP header.
Tagging and Marking
In a QoS class, you can configure whether to add or change the DSCP (DiffServ
Code Point) value, IEEE 802.1p priority level and VLAN ID number in a matched
packet. When the packet passes through a compatible network, the networking
device, such as a backbone switch, can provide specific treatment or service
based on the tag or marker.
11.3 The Quality of Service General Screen
Click Advanced Setup > Quality of Service to open the screen as shown next.
Use this screen to enable or disable QoS and set the default DSCP value for
incoming traffic does not match a class. See
for more
information.
Figure 63 QoS General