Configuring Class of Service
147
Use the buttons to perform the following tasks:
To clear the hit count for one or more configured rules within an ACL, select the rule entry and
click
Clear Rule Hit Counte
r. You must confirm the action before the hit count is cleared for the
selected rule(s).
To clear the hit count for an ACL, select the ACL type from the ACL Type menu, select the ACL ID
from the ACL Identifier menu, and then click
Clear ACL Counters
. You must confirm the action
before the hit count is cleared for the selected ACL.
Configuring Class of Service
The Class of Service (CoS) queueing feature lets you directly configure certain aspects of switch
queueing. This provides the desired QoS behavior for different types of network traffic when the com-
plexities of DiffServ are not required. The priority of a packet arriving at an interface can be used to
steer the packet to the appropriate outbound CoS queue through a mapping table. CoS queue charac-
teristics that affect queue mapping, such as minimum guaranteed bandwidth, transmission rate shap-
ing, etc., are user-configurable at the queue (or port) level.
802.1p CoS Mapping Configuration
The IEEE 802.1p feature allows traffic prioritization at the MAC level. The switch can prioritize traffic
based on the 802.1p tag attached to the L2 frame. Each port on the switch has multiple queues to give
preference to certain packets over others based on the class of service (CoS) criteria you specify.
When a packet is queued for transmission in a port, the rate at which it is serviced depends on how the
queue is configured and possibly the amount of traffic present in the other queues of the port. If a delay
is necessary, packets get held in the queue until the scheduler authorizes the queue for transmission.
Use the 802.1p CoS Mapping Configuration page to assign 802.1p priority values to various traffic
classes on one or more interfaces.
To display the
page, click
QoS
>
Class of Service
in the navigation pane, and ensure that the
802.1p
tab is selected.
Rule Attributes
Each action — beyond the basic Permit and Deny actions — to perform on the traffic that
matches the rule.
Hit Count
Indicates the number of packets that match the configured rule in an ACL. If a rule is
configured without rate limit, then the hit count is the number of matched packets forwarded
or discarded by the port. If a rule is configured with rate limit, then if the sent traffic rate
exceeds the configured rate, the hit count displays the matched packet count equal to the
sent rate, despite packets getting dropped beyond the configured limit. If the sent traffic rate
is less than the configured rate, the hit count displays only the matched packet count.
Field
Description
