Quality of Service | 17712Quality of ServiceThis chapter contains the following major sections:• Using Differentiated Services (DiffServ) on page 177•Deploying DiffServ on page 180•Monitoring DiffServ on page 184•Configuring Differentiated Services by Department on page 191•Configuring Differentiated Services for Voice over IP on page 194Using Differentiated Services (DiffServ)This section contains the following subsections:• Deploying DiffServ on page 180• Monitoring DiffServ on page 184• Configuring Differentiated Services by Department on page 191• Configuring Differentiated Services for Voice over IP on page 194For syntax details on commands discussed in this chapter, see Chapter 19 (Quality of Service (QoS)Commands) in the SFTOS Command Reference. That chapter also provides syntax statements for Class ofService commands (CoS). See also, in this chapter, Using Differentiated Services (DiffServ) on page 177,for more information on controlling traffic.Differentiated Services (DiffServ) is one technique for implementing Quality of Service (QoS) policies.Using DiffServ in your network allows you to directly configure the relevant parameters on the switchesand routers rather than using a resource reservation protocol.This section explains how to configure theS-Series to identify which traffic class a packet belongs to and how the packet should be handled toprovide the desired quality of service. As implemented on the S-Series, DiffServ allows you to controlwhat traffic is accepted, what traffic is transmitted, and what bandwidth guarantees are provided.How you configure DiffServ support on the S-Series will likely vary depending on the role of the switch inyour network:• Edge device: An edge device handles ingress traffic, flowing towards the core of the network, andegress traffic, flowing away from the core. An edge device will segregate inbound traffic into a smallset of traffic classes, and is responsible for determining a packet’s classification. Classification will beprimarily based on the contents of the Layer 3 and Layer 4 headers, and will be recorded in theDifferentiated Services Code Point (DSCP) added to a packet’s IP header.
