Qos Configuration; Qos Overview - D-Link DI-1750 Reference Manual

9. QoS Configuration

This chapter explains what is Quality of Service (QoS for short ), and the service models that fulfill it.
Moreover, introduce queue algorithms of Qos.
Configuration.

9.1 QoS Overview

This chapter explains quality of service (QoS) and the service models that embody it. In addition, QoS
Queue Algorithm will be indroduced. For the correlative configuration, see the QoS Configuration.
9.1.1 What is QoS
QoS refers to the ability of a network to provide improved service to selected network traffic over
various underlying technologies including Frame Relay, ATM (Asynchronous Transfer Mode), Ethernet
and 802.1 networks, and IP-routed networks. In command to ensure the QoS in the network, the
Router provides queueing, scheduling, and QoS signalling features. The Router features enable
networks to control and predictably service a variety of networked applications and traffic types.
1. End-to-End QoS Models
A service model, also called a level of service, describes a set of end-to-end QoS capabilities.
End-to-end QoS is the ability of the network to deliver service required by specific network traffic from
one end of the network to another. The QoS software supports three types of service models: best
effort, integrated, and differentiated services.
♦ Best-Effort Service
Best effort is a single service model in which an application sends data whenever it must, in any
quantity, and without requesting permission or first informing the network. For best-effort service,
the network delivers data if it can, without any assurance of reliability, delay bounds, or throughput.
The QoS feature that implements best-effort service is FIFO queueing.
♦ Integrated Service
Integrated service is a multiple service model that can accommodate multiple QoS requirements. In
this model the application requests a specific kind of service from the network before it sends data.
The request is made by explicit signalling; the application informs the network of its traffic profile
and requests a particular kind of service that can encompass its bandwidth and delay requirements.
The application is expected to send data only after it gets a confirmation from the network. It is also
expected to send data that lies within its described traffic profile.
The network performs admission control, based on information from the application and available
network resources. It also commits to meeting the QoS requirements of the application as long as the
traffic remains within the profile specifications.
The QoS provide Controlled Load Service and Guaranteed Rate Service by the Resource Reservation
Protocol (RSVP).
Controlled Load Service, which allows applications to have low delay and high throughput even during
times of congestion. D-Link QoS uses Weighted Fair Queueing (WFQ) to provide this kind of service..
2. Differentiated Service
Differentiated service is a multiple service model that can satisfy differing QoS requirements. However,
unlike in the integrated service model, an application using differentiated service does not explicitly
signal the router before sending data.
For differentiated service, the network tries to deliver a particular kind of service based on the QoS
specified by each packet. This specification can occur in different ways, for example, using the IP
Precedence bit settings in IP packets or source and destination addresses. The router uses the QoS
specification to classify and to perform intelligent queueing.
Model Name
The relating configuration please refer to Qos
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