Specifying Policies - Nortel 4524GT Configuration

32 Chapter 1 An Introduction to Policy-Enabled Networks
If an IPv4 packet is received from an untrusted port and it does not match
any one of the classifier elements installed by the user on the port, the
Nortel Ethernet Routing Switch 4500 Series uses default system classifiers
to change the packet DSCP, IEEE 802.1p priority, and drop precedence as
follows:
•
•
System requirements for network service class definitions and mapping to
DSCP
DiffServ Code Point
(DSCP)
CS7, CS6
EF, CS5
AF1x, CS1
AF4x, AF3x, AF2x,
CS4, CS3, CS2, DF
(CSO), all unspecified
DSCPs

Specifying policies

Configure interface groups (role combinations), classification criteria, actions, and
meters before attempting to reference that data in a policy.
When network traffic attributes match those specified in a traffic pattern, the
policy instructs the network device to perform a specified action on each
packet that passes through it. A policy is a set of rules and actions that
are applied to specific ports.
When configuring policies, it is important to consider that the policy with the
highest precedence is evaluated first, then the policy with the next lowest
precedence and so on. The valid precedence range for QoS policies is
1 to 7. For example, with a precedence of 1 to 7, the system begins the
evaluation with 7, moves on to 6, and so forth.
Copyright © 2007, Nortel Networks
.
If the packet is tagged, the 802.1p user priority value is derived from the
DSCP-to-CoS mapping table using the best effort DSCP, which is 0.
If an IPv4 packet is untagged, the Nortel Ethernet Routing Switch 4500
Series uses the default classifier to change the DSCP based on the
default IEEE 802.1p priority of the ingress untrusted port to index into
the DSCP-to-CoS mapping table to determine the DSCP value.
Logical
queue
number
2
1
3
4
Nortel Ethernet Routing Switch 4500 Series
Configuration — Quality of Service
NN47205-504 (322816-B)
5.1 23 November 2007
Recommended
scheduler
Weighted
Priority
Weighted
Weighted
ATTENTION
03.01 Standard
Network service
class
Network
Premium
Bronze
Standard