Configuring the ECN330-switch
342 1553-KDU 137 365 Uen D 2006-06-16
6.15 Quality of Service
The commands described in this section are used to configure Quality of
Service (QoS) classification criteria and service policies. Differentiated Services
(DiffServ) provides policy-based management mechanisms used for prioritizing
network resources to meet the requirements of specific traffic types on a per hop
basis. Each packet is classified upon entry into the network based on access
lists, IP Precedence, DSCP values, or VLAN lists. Using access lists allows
traffic to be selected based on Layer 2, Layer 3, or Layer 4 information contained
in each packet. Based on configured network policies, different kinds of traffic
can be marked for different kinds of forwarding.
All switches or routers that access the Internet rely on class information to
provide the same forwarding treatment to packets in the same class. Class
information can be assigned by end hosts, or switches or routers along the path.
Priority can then be assigned based on a general policy, or a detailed
examination of the packet. However, note that detailed examination of packets
should take place close to the network edge so that core switches and routers
are not overloaded.
Switches and routers along the path can use class information to prioritize the
resources allocated to different traffic classes. The manner in which an
individual device handles traffic in the DiffServ architecture is called per-hop
behavior. All devices along a path should be configured in a consistent manner
to construct a consistent end-to-end QoS solution.
Note: Only one rule per Class Map can be configured. However, multiple
classes can be included in a Policy Map.
Note: A Class Map must be created before creating a Policy Map.
6.15.1 Configuring Quality of Service Parameters
To create a service policy for a specific category or ingress traffic, follow these
steps:
1. Use the “Class Map” to designate a class name for a specific category of
traffic.
2. Edit the rules for each class to specify a type of traffic based on an access
list, a DSCP or IP Precedence value, or a VLAN.
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