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Chapter 17 Quality of Service (QoS)
P-2612HNU-Fx User’s Guide
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•Use the Monitor screen (Section 17.5 on page 233) to view the ZyXEL Device’s
QoS-related packet statistics.
17.1.2 What You Need to Know
The following terms and concepts may help as you read 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.
17.2 The QoS General Screen
Use this screen to enable or disable QoS, and select to have the ZyXEL Device
assign the allowable upstream bandwidth.