Configuration Examples
192
XS728T ProSAFE 28-Port 10-Gigabit L2+ Smart Switch
To configure DiffServ, you must define service levels, namely the forwarding classes, or
PHBs identified by a given DSCP value, on the egress interface. You define the service
levels by configuring BA classes for each.
Create 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. Several distinct QoS
actions are associated with traffic conditioning:
• Dropping. Drops 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. Marks and remarks the DiffServ code point in a packet with the DSCP
value representing the service level associated with a particular DiffServ traffic class.
• Marking CoS (802.1p). Sets the 3-bit priority field in the first or 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 exist. This is useful for assigning a Layer 2 priority level based on a
DiffServ forwarding class (that is, DSCP or IP precedence value) definition to convey
some QoS characteristics to downstream switches that do not routinely look at the DSCP
value in the IP header.
• Policing. A method of limiting incoming traffic associated with a particular class so that it
conforms to the terms of the TCS. Special treatment can be applied to out-of-profile
packets that are either in excess of the conformance specification or are non-conformant.
The DiffServ feature supports the following types of traffic policing treatments (actions):
• Drop. The packet is dropped.
• Mark CoS. 802.1p user priority bits are marked or re-marked and forwarded.
• Mark DSCP. The packet DSCP is marked or re-marked and forwarded.
• Send. The packet is forwarded without DiffServ modification.
Color mode awareness. Policing in the DiffServ feature uses either color blind or color
aware mode. Color blind mode ignores the coloration (marking) of the incoming packet.
Color aware mode considers the current packet marking when determining the policing
outcome. An auxiliary traffic class is used with the policing definition to specify a value for
one of the 802.1p, IP DSCP, or IP precedence fields designating the incoming color value
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