36

Differentiated Services

This chapter describes how Differentiated Services (DiffServ) fits into a quality of service strategy and shows you how to configure Two Rate Three Color Marker traffic policing on the Switch.

36.1 DiffServ Overview

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.

36.1.1 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 can define up to 64 service levels and the remaining 2 bits are defined as currently unused (CU). The following figure illustrates the DS field.

Figure 170 DiffServ: Differentiated Service Field

DSCP (6 bits)

CU (2 bits)

DSCP is backward compatible with the three precedence bits in the ToS octet so that non-DiffServ compliant, ToS-enabled network device will not conflict with the DSCP mapping.

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ZyXEL Communications metrogigabit switch manual Differentiated Services, DiffServ Overview, 341

metrogigabit switch specifications

ZyXEL Communications has long been a prominent player in the networking hardware industry, providing innovative solutions that cater to both business and consumer markets. Among their notable offerings is the Metrogigabit switch, a device designed to meet the high demands of modern networks.

The ZyXEL Metrogigabit switch is primarily aimed at service providers and large enterprises, recognizing the need for seamless connectivity in an increasingly digital world. This switch is engineered for scalability, enabling users to effortlessly expand their network as their operational needs grow. With support for high bandwidth, it is particularly suited for environments requiring extensive data traffic management, such as data centers and campus networks.

One of the standout features of the Metrogigabit switch is its high-density gigabit Ethernet ports, which provide a backbone for reliable data transmission. The switch typically supports multiple 10G SFP+ uplinks, ensuring fast and efficient connections to upstream devices. This capability allows users to configure their networks to handle large volumes of data quickly and without interruption.

In terms of technology, the Metrogigabit switch leverages advanced Layer 2 and Layer 3 functionalities. This includes features such as VLAN support for traffic segmentation, Quality of Service (QoS) for prioritizing mission-critical applications, and robust multicast management. These capabilities contribute to enhanced network efficiency and performance.

Another characteristic that sets the ZyXEL Metrogigabit switch apart is its built-in security features. The device is designed to protect network integrity through mechanisms like port security, access control lists, and advanced authentication protocols. This focus on security helps prepare businesses to counteract potential threats in a landscape where cyber attacks are increasingly sophisticated.

Moreover, the switch is equipped with a user-friendly management interface, which simplifies the process of monitoring and configuring network settings. This is complemented by support for SNMP and RMON, allowing network administrators to leverage tools for effective performance monitoring.

In summary, the ZyXEL Metrogigabit switch is an essential tool for organizations seeking robust performance, reliability, and security in their networking infrastructure. With its high-density ports, flexible configuration options, and comprehensive management features, it provides a strong foundation for building efficient and scalable networks. Whether for service providers or enterprises, this switch stands out as a reliable choice in the fast-evolving technological landscape.