Chapter
Configuring the Switch
1
24-Port 10/100 + 4-Port Ggabt Swtch wth WebVew and Power over Ethernet
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 .
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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 .
Prorty Level Mappngs
Prorty Level
Traffc Type
1
Background
2
(Spare)
0
(default) Best Effort
3
Excellent Effort
4
Controlled Load
5
Video, less than 100 ms latency and jitter
6
Voice, 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 Servce
CoS value . (Range: 0-7, where 7 is the
highest priority queue)
Queue (0-)
The output priority queue . (Range: 0-3,
where 3 is the highest CoS priority queue)
