ZyXEL Communications GS2200-24P Series, User Manual, Page: 261 / 360

GS2200-24/24P User’s Guide
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Differentiated Services
29.1 Overview
This chapter shows you how to configure Differentiated Services (DiffServ) on the
Switch.
Quality of Service (QoS) is used to prioritize source-to-destination traffic flows. All
packets in the flow are given the same priority. You can use CoS (class of service)
to give different priorities to different packet types.
DiffServ is a class of service (CoS) model that marks packets so that they receive
specific per-hop treatment at DiffServ-compliant network devices along the route
based on the application types and traffic flow. Packets are marked with DiffServ
Code Points (DSCPs) indicating the level of service desired. This allows the
intermediary DiffServ-compliant network devices to handle the packets differently
depending on the code points without the need to negotiate paths or remember
state information for every flow. In addition, applications do not have to request a
particular service or give advanced notice of where the traffic is going.
29.1.1 What You Can Do
• Use the DiffServ screen ( Section 29.2 on page 263 ) to activate DiffServ to
apply marking rules or IEEE 802.1p priority mapping on the Switch.
• Use the DSCP screen ( Section 29.3.1 on page 264 ) to change the DSCP-IEEE
802.1p mapping.
29.1.2 What You Need to Know
Read on for concepts on Differentiated Services that can help you configure the
screens in this chapter.
DSCP and Per-Hop Behavior
DiffServ defines a new DS (Differentiated Services) field to replace the Type of
Service (ToS) field in the IP header. The DS field contains a 6-bit DSCP field which