Extreme Networks EPICenter 5.0, Manual

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Policy Configuration
EPICenter Concepts and Solutions Guide 161
The Grouping Manager allows groups to contain members of different resource types, including other
groups. However, when you are setting up groups for use with the Policy Manager, it is recommended
that you create relatively simple groups that contain only the resources that you intend to use for a
single purpose.
For example, when you use a group to define a traffic flow, you are specifying that all members of that
group (that can be mapped to an IP address) are endpoints of the specified traffic flow. If you define a
large group that is used for a variety of purposes, especially one with subgroups as members, you need
to ensure that it does not contain members that will result in policy traffic flows other than the ones you
intended to specify.
Furthermore, if the membership of the group changes after you have implemented your policies, the
endpoints for the traffic flow will change. If you have policy auto-configuration enabled, new policy
rules will automatically be computed and configured on your network, based on the new traffic flow
definition.
Precedence Relationships within the Policy Manager
The EPICenter Policy Manager has several types of precedence relationships:
• Precedence between resources within the scope of a policy
• Precedence between EPICenter policies
• Precedence between the QoS rules implemented on an Extreme Networks device
Each of these has a somewhat different use and effect.
Precedence between the resources in a policy scope is used to determine which QoS profile specification
should be used when a particular device is specified multiple times within a scope definition.
Policy precedence (precedence between policies) is used to determine which policy should be used when
multiple policies could apply to the same traffic flow. If this occurs, the policy with higher priority is
used by the switch over policies of lower priority. Policy precedence only controls the relationships
between policies of the same type. Policies of different types have a predefined precedence relationship:
IP QoS policies are the highest priority, Source Port QoS policies are second, and VLAN QoS policies
have the lowest priority.
For IP policies, policy precedence is implemented by assigning precedence numbers to IP access-lists
that are configured to the devices. These precedence numbers may be different on different devices
depending on how many policies are active on a given device. The actual IP access-list precedence
number is not as important because it is the relative ordering between the precedence numbers from the
access-list that matters.
Policy Configuration
The EPICenter Policy Manager supports automatic configuration of QoS policies. If Auto Configuration
is enabled, every change you make on a device or within the EPICenter software has the potential to
trigger an immediate recomputation and reconfiguration of the QoS policies on your network. An
automatic reconfiguration can be triggered by any of the following events:
• Changes to group memberships made through the Grouping Manager or Inventory Manager that
affect a group used to define a policy endpoint or policy scope