Creating Policies - NETGEAR GS108T-200NAS Software Administration Manual

You can combine these classifiers with logical AND or OR operations to build complex MF-
classifiers (by specifying a class type of all or any, respectively). That is, within a single class,
multiple match criteria are grouped together as an AND expression or a sequential OR expression,
depending on the defined class type. Only classes of the same type can be nested; class nesting
does not allow for the negation (i.e., exclude option) of the referenced class.
To configure DiffServ, you must define service levels, namely the forwarding classes/PHBs
identified by a given DSCP value, on the egress interface. These service levels are defined by
configuring BA classes for each.

Creating Policies

Use DiffServ policies to associate a collection of classes that you configure with one or more QoS
policy statements. The result of this association is referred to as a policy.
From a DiffServ perspective, there are two types of policies:
• Traffic Conditioning Policy: a policy applied to a DiffServ traffic class
• Service Provisioning Policy: a policy applied to a DiffServ service level
You must manually configure the various statements and rules used in the traffic conditioning and
service provisioning policies to achieve the desired Traffic Conditioning Specification (TCS) and
the Service Level Specification (SLS) operation, respectively.
Traffic Conditioning Policy
Traffic conditioning pertains to actions performed on incoming traffic. There are several distinct
QoS actions associated with traffic conditioning:
• Dropping: drop a packet upon arrival. This is useful for emulating access control list
operation using DiffServ, especially when DiffServ and ACL cannot co-exist on the same
interface.
• Marking IP DSCP or IP Precedence: marking/re-marking the DiffServ code point in a
packet with the DSCP value representing the service level associated with a particular
DiffServ traffic class. Alternatively, the IP Precedence value of the packet can be marked/re-
marked.
• Marking CoS (802.1p): sets the three-bit priority field in the first/only 802.1p header to a
specified value when packets are transmitted for the traffic class. An 802.1p header is inserted
if it does not already exist. This is useful for assigning a layer 2 priority level based on a
DiffServ forwarding class (i.e., DSCP or IP Precedence value) definition to convey some QoS
characteristics to downstream switches which do not routinely look at the DSCP value in the
IP header.
Configuration Examples
GS108T and GS110TP Smart Switch Software Administration Manual
v1.0, April 2010
B-9