Chapter 14 Quality of Service (QoS)
P-870HN-51D User’s Guide
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•The Monitor screen lets you view the P-870HN-51D's QoS-related packet
statistics (Section 14.7 on page 183).
14.2 What You Need to Know
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.
14.3 The Quality of Service General Screen
Use this screen to enable or disable QoS, set the upstream bandwidth for WAN
and downsteam bandwidth for LAN/WLAN.
Upstream bandwdith refers to resources alloted to traffic, which goes from the
LAN device to the WAN device. On the other hand, downstream bandwidth refers
to resources alloted to traffic that comes back from the WAN device to the LAN
device
