RackSwitch G8000 Application Guide
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Chapter 6: Quality of Service BMD00041, November 2008
Overview
QoS helps you allocate guaranteed bandwidth to the critical applications, and limit bandwidth
for less critical applications. Applications such as video and voice must have a certain amount
of bandwidth to work correctly; using QoS, you can provide that bandwidth when necessary.
Also, you can put a high priority on applications that are sensitive to timing out or that cannot
tolerate delay, by assigning their traffic to a high-priority queue.
By assigning QoS levels to traffic flows on your network, you can ensure that network
resources are allocated where they are needed most. QoS features allow you to prioritize net-
work traffic, thereby providing better service for selected applications.
Figure 6-1 shows the basic QoS model used by the switch.
Figure 6-1 QoS Model
The basic QoS model works as follows:
Classify traffic:
Read DSCP value.
Read 802.1p priority value.
Match ACL filter parameters.
Perform actions:
Permit packets.
Deny packets.
Map 802.1p Priority to COS queue.
Map DSCP to COS queue.
Set the number of COS queues (1-8).
Queue and schedule traffic:
Place packets in one of the COS queues.
Schedule transmission based on the COS queue.
Ports
ACL
Filter
Permit/Deny
Classify
Packets
Perform
Actions
Egress
Ingress
COS
Queue
Queue and
Schedule
