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Overview

Quality of Service (QoS) is a mechanism for providing differentiated services for different types of network traffic. The Passport 8000 Series switch implements QoS by providing support for the Differentiated Services (DiffServ) architecture. A DiffServ architecture enables service discrimination of traffic flows or microflows by offering network resources higher classes of service at the expense of lower classes of service. This architecture allows you to prioritize a microflow or aggregate flow and provides IP Quality of Service (QoS) that is scalable.

RFCs 2474 and 2475 define the DiffServ (DS) field, a one-byte (eight-bit) field in the IP header. The first 6 bits of this field, called the DiffServ codepoint (DSCP), are used in the DiffServ architecture. The marking of the DS codepoint dictates the forwarding treatment given to the packet at each hop. This marking occurs at the edge of the DiffServ domain and is based on the policy or filter for the particular microflow or an aggregate flow.

Within the DiffServ network, the marked packets are placed in a queue according to their marking. For example, if a video stream is marked to receive the highest priority, it is placed in a high-priority queue. As those packets traverse the DiffServ network, the video stream is forwarded before any other packets.


Note Note: The Passport 8600 Switch is shipped with QoS parameters already set to default values that will operate successfully in your network. You need only enable DiffServ access ports and core ports.

See also

See also:


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