Quality of Service
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Instruction Manual - NXA-ENET8-POE+
Quality of Service
This chapter describes the following tasks required to apply QoS policies:
Class Map
- Creates a map which identifies a specific class of traffic.
Policy Map
- Sets the boundary parameters used for monitoring inbound traffic, and the action to take for conforming and
non-conforming traffic.
Binding to a Port
- Applies a policy map to an ingress port.
Overview
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, VLAN lists, CoS values, or source ports. Using access lists allows you select traffic 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:
You can configure up to 16 rules per class map. You can also include multiple classes in a policy map.
NOTE:
You should create a class map before creating a policy map. Otherwise, you will not be able to select a class map from the
policy rule settings screen (see page 210).
Command Usage
To create a service policy for a specific category or ingress traffic, perform these steps:
1.
Use the Configure Class (Add) page to designate a class name for a specific category of traffic.
2.
Use the Configure Class (Add Rule) page to edit the rules for each class which specify a type of traffic based on an access list,
a DSCP or IP Precedence value, a VLAN, or a CoS value.
3.
Use the Configure Policy (Add) page to designate a policy name for a specific manner in which ingress traffic will be handled.
4.
Use the Configure Policy (Add Rule) page to add one or more classes to the policy map. Assign policy rules to each class by
setting the QoS value (CoS or PHB) to be assigned to the matching traffic class. The policy rule can also be configured to
monitor the maximum throughput and burst rate. Then specify the action to take for conforming traffic, or the action to take
for a policy violation.
5.
Use the Configure Interface page to assign a policy map to a specific interface.
NOTE:
Up to 16 classes can be included in a policy map.
Configuring a Class Map
A class map is used for matching packets to a specified class. Use the Traffic > DiffServ (Configure Class) page to configure a class
map.
Command Usage
The class map is used with a policy map (page 128) to create a service policy (page 130) for a specific interface that
defines packet classification, service tagging, and bandwidth policing. Note that one or more class maps can be assigned
to a policy map.
Up to 32 class maps can be configured.
The following table lists the options on this page:
Traffic - Diffserv Options
Add
Class Name
Name of the class map. (Range: 1-32 characters)
Type
Only one match command is permitted per class map, so the match-any field refers to the criteria
specified by the lone match command.
Description
A brief description of a class map. (Range: 1-64 characters)
Add Rule
Class Name
Name of the class map.