Chapter 14 Quality of Service (QoS)

•The Monitor screen lets you view the P-870HN-51D's QoS-related packet statistics (Section 14.7 on page 183).

14.2What 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

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P-870HN-51D User’s Guide