Chapter 5

Configuring the Switch

Generate  This button is used to generate the host key pair.. Note that you must first generate the host key pair before you can enable the SSH server..

Clear  This button clears the host key from both volatile memory (RAM) and non-volatile memory (Flash)..

QoS

Network traffic is usually unpredictable, and the only basic assurance that can be offered is best effort traffic delivery.. To overcome this challenge, Quality of Service (QoS) is applied throughout the network.. This ensures that network traffic is prioritized according to specified criteria, and that specific traffic receives preferential treatment.. QoS in the network optimizes network performance and entails two basic facilities:

Classifying incoming traffic into handling classes, based on an attribute, including:

The ingress interface

Packet content

A combination of these attributes

Providing various mechanisms for determining the allocation of network resources to different handling classes, including:

The assignment of network traffic to a particular hardware queue

The assignment of internal resources

Traffic shaping

The terms Class of Service (CoS) and QoS are used in the following context:

CoS provides varying Layer 2 traffic services.. CoS refers to classification of traffic to traffic-classes, which are handled as an aggregate whole, with no per-flow settings.. CoS is usually related to the 802..1p service that classifies flows according to their Layer 2 priority, as set in the VLAN header..

QoS refers to Layer 2 traffic and above.. QoS handles per- flow settings, even within a single traffic class..

QoS > CoS Settings

Class of Service (CoS) allows you to specify which data packets have greater precedence when traffic is buffered in the Switch due to congestion.. The Switch supports CoS with four priority queues for each port.. Data packets in a port’s high-priority queue will be transmitted before those in the lower-priority queues.. You can set the default priority for each interface, and configure the mapping of frame priority tags to the Switch’s priority queues..

QoS > Cos Settings

The priority levels recommended in the IEEE 802..1p standard for various network applications are shown in the following table.. However, you can map the priority levels to the Switch’s output queues in any way that benefits application traffic for your own network..

 

Priority Level Mappings

 

 

Priority Level

Traffic Type

 

 

1

Background

2

(Spare)

0

(default) Best Effort

3

Excellent Effort

4

Controlled Load

5Video, less than 100 ms latency and jitter

6Voice, less than 10 ms latency and jitter

7

Network Control

CoS to Queue

Assign priorities to the traffic classes (output queues) for the selected interface..

Class of Service  CoS value.. (Range: 0-7, where 7 is the highest priority queue)

Queue (0-3) The output priority queue.. (Range: 0-3, where 3 is the highest CoS priority queue)

24-Port 10/100 + 4-Port Gigabit Switch with WebView and Power over Ethernet

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Linksys SRW224G4P manual QoS CoS Settings, CoS to Queue