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Chapter 9 Quality of Service (QoS)
FMG3024-D10A / FMG3025-D10A Series User’s Guide
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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.
9.2 The QoS General Screen
Use this screen to enable or disable QoS, set the bandwidth, and select to have the Device
automatically assign priority to upstream traffic according to the IEEE 802.1p priority level, IP
precedence or packet length.
Click Network Setting > QoS to open the General screen.
Figure 53 Network Setting > QoS > General