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QSW-2900-24T-AC
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Qtech QSW-2900-24T-AC [133/209] Chapter 9

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Chapter 9 QOS Configuration

9.1 Brief introduction of QOS

In traditional packet network, all packets are equal to be handled. Each switch and router handles packet by

FIFO to make best effort to send packets to the destination and not to guarantee the transmission delay and delay

variation.

With the fast development of computer network, the requirement of network is higher. More and more voice,

image and important data which are sensitive about bandwidth, delay and jittering transferred through network,

which greatly enrich network service resources and the requirement of quality of service is higher for the network

congestion. Now, Ethernet becomes the leading technology in every independent LAN, and many LAN in the form

of Ethernet have become a part of internet. With the development of Ethernet technology, Ethernet connecting will

become one of main connecting for internet users. To realize end-to-end QoS solution has to consider the service

guarantee of Ethernet QoS, which needs Ethernet device applies to Ethernet technology to provide different levels of

QoS guarantee for different types of service flow, especially the service flow highly requiring delay and jitter.

1. Flow

Flow is traffic which means all packets through switch.

2. Traffic classification

Traffic classification means adopting certain regulation to recognize packet with some features. Clasification

rule means the filtration regulation configured by the administrator according to managing need which can be simple,

such as realizing flow with the feature of different priority according to the ToS field of IP packet head and can be

complicated, such as information of integrated link layer (layer 2), network layer (layer 3), transmission layer (layer

4), such as MAC address, IP protocol, source address, destination address or application program interface number to

classify packet. General classification is limited in the head of encapsulation packet. Use packet content to be

classification standard is singular.

3. Access control list

To classify flow is to provide service distinctively which must be connected resource distributing. To adopt

which kind of flow control is related to the stage it is in and the current load of the network. For example: monitor

packet according to the promised average speed rate when the packet is in the network and queue scheduling manage

the packet before it is out of the node.

4. Packet filtration

Packet filtration is to filtrate service flow, such as deny, that is, deny the service flow which is matching the

traffic classification and permit other flows to pass. System adopts complicated flow classification to filtrate all kinds

of information of service layer 2 packets to deny useless, unreliable, and doubtable service flow to strengthen

network security.

Two key points of realizing packet filtration:

Step 1: Classify ingress flows according to some regulation;

Step 2: Filtrate distinct flow by denying. Deny is default accessing control.

5. Flow monitor

In order to serve customers better with the limited network resources, QoS can monitor service flow of

specified user in ingress interface, which can adapt to the distributed network resources.

6. Interface speed limitation

Interface speed limitation is the speed limit based on interface which limits the total speed rate of interface

outputting packet.

7. Redirection

User can re-specify the packet transmission interface based on the need of its own QoS strategies.

Qtech QSW-2900-24T-AC [133/209] Chapter 9

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