Extreme Networks ExtremeWare XOS 11.1, Руководство пользователя

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ExtremeWare XOS 11.1 Concepts Guide
179
11 Policies and ACLs
This chapter describes the following topics:
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Policy Manager on page 179
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Creating and Editing Policies on page 179
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Checking Policies on page 180
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Refreshing Policies on page 181
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Applying Policies on page 181
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ACL Policies on page 182
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Routing Policies on page 190
Policy Manager
One of the processes that make up the ExtremeWare XOS system is the policy manager. The policy
manager is responsible for maintaining a set of policy statements in a policy database and
communicating these policy statements to the applications that request them.
Policies are used by the routing protocol applications to control the advertisement, reception, and use of
routing information by the switch. Using policies, a set of routes can be selectively permitted (or
denied) based on their attributes, for advertisements in the routing domain. The routing protocol
application can also modify the attributes of the routing information, based on the policy statements.
Policies are also used by the access control list (ACL) application to perform packet filtering and
forwarding decisions on packets. The ACL application will program these policies into the packet
filtering hardware on the switch. Packets can be dropped, forwarded, moved to a different QoS profile,
or counted, based on the policy statements provided by the policy manager.
Creating and Editing Policies
A policy is created by writing a text file that contains a series of rule entries describing match conditions
and actions to take. Prior to release 11.0, all policies were created by writing a text file on a separate
machine and then downloading it to the switch. Once on the switch, the file was then loaded into a
policy database to be used by applications on the switch. With release 11.0, policy text files can also be
created and edited directly on the switch.
NOTE
Although ExtremeWare XOS does not prohibit mixing ACL and routing type entries in a policy file, it is strongly
recommended that you do not mix the entries, and you use separate policy files for ACL and routing policies.