Cisco Systems SRW248G4PK9NA User Manual

QoS Features and Components

413

Cisco Small Business 300 Series Managed Switch Administration Guide 

The QoS feature is used to optimize network performance.

QoS provides the following:

•

Classification of incoming traffic to traffic classes, based on attributes, 
including:

-

Device Configuration

-

Ingress interface

-

Packet content

-

Combination of these attributes

QoS includes the following:

•

Traffic Classification—Classifies each incoming packet as belonging to a 
specific traffic flow, based on the packet contents and/or the port. The 
classification is done by ACL (Access Control List), and only traffic that 
meets the ACL criteria is subject to CoS or QoS classification.

•

Assignment to Hardware Queues—Assigns incoming packets to 
forwarding queues. Packets are sent to a particular queue for handling as a 
function of the traffic class to which they belong. See 

•

Other Traffic Class-Handling Attribute—Applies QoS mechanisms to 
various classes, including bandwidth management.

The QoS mode that is selected applies to all interfaces in the system.

•

Basic Mode—Class of Service (CoS).

All traffic of the same class receives the same treatment, which is the single 
QoS action of determining the egress queue on the egress port, based on 
the indicated QoS value in the incoming frame. This can be the VLAN 
Priority Tag (VPT) 802.1p value in Layer 2 and the Differentiated Service 
Code Point (DSCP) value for IPv4 or Traffic Class (TC) value for IPv6 in 
Layer 3. When operating in Basic Mode, the device trusts this external 
assigned QoS value. The external assigned QoS value of a packet 
determines its traffic class and QoS.