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			101 lines
		
	
	
		
			5.1 KiB
		
	
	
	
		
			XML
		
	
	
	
	
	
			
		
		
	
	
			101 lines
		
	
	
		
			5.1 KiB
		
	
	
	
		
			XML
		
	
	
	
	
	
<?xml version='1.0' encoding='utf-8' ?>
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<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY % BOOK_ENTITIES SYSTEM "cloudstack.ent">
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%BOOK_ENTITIES;
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]>
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<!-- Licensed to the Apache Software Foundation (ASF) under one
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 or more contributor license agreements.  See the NOTICE file
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 distributed with this work for additional information
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 regarding copyright ownership.  The ASF licenses this file
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 to you under the Apache License, Version 2.0 (the
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 "License"); you may not use this file except in compliance
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 with the License.  You may obtain a copy of the License at
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 http://www.apache.org/licenses/LICENSE-2.0
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 Unless required by applicable law or agreed to in writing,
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 software distributed under the License is distributed on an
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 "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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 KIND, either express or implied.  See the License for the
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 specific language governing permissions and limitations
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 under the License.
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-->
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<section id="persistent-network">
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  <title>Persistent Networks</title>
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  <para>The network that you can provision without having to deploy any VMs on it is called a
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    persistent network. A persistent network can be part of a VPC or a non-VPC environment.</para>
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  <para>When you create other types of network, a network is only a database entry until the first
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    VM is created on that network. When the first VM is created, a VLAN ID is assigned and the
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    network is provisioned. Also, when the last VM is destroyed, the VLAN ID is released and the
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    network is no longer available. With the addition of persistent network, you will have the
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    ability to create a network in &PRODUCT; in which physical devices can be deployed without
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    having to run any VMs. Additionally, you can deploy physical devices on that network.</para>
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  <para>One of the advantages of having a persistent network is that you can create a VPC with a tier
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    consisting of only physical devices. For example, you might create a VPC for a three-tier
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    application, deploy VMs for Web and Application tier, and use physical machines for the
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    Database tier. Another use case is that if you are providing services by using physical
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    hardware, you can define the network as persistent and therefore even if all its VMs are
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    destroyed the services will not be discontinued.</para>
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  <section id="persistent-network-consideration">
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    <title>Persistent Network Considerations</title>
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    <itemizedlist>
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      <listitem>
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        <para>Persistent network is designed for isolated networks.</para>
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      </listitem>
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      <listitem>
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        <para>All default network offerings are non-persistent.</para>
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      </listitem>
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      <listitem>
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        <para>A network offering cannot be editable because changing it affects the behavior of the
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          existing networks that were created using this network offering.</para>
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      </listitem>
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      <listitem>
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        <para>When you create a guest network, the network offering that you select defines the
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          network persistence. This in turn depends on whether persistent network is enabled in the
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          selected network offering. </para>
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      </listitem>
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      <listitem>
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        <para>An existing network can be made persistent by changing its network offering to an
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          offering that has the Persistent option enabled. While setting this property, even if the
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          network has no running VMs, the network is provisioned. </para>
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      </listitem>
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      <listitem>
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        <para>An existing network can be made non-persistent by changing its network offering to an
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          offering that has the Persistent option disabled. If the network has no running VMs,
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          during the next network garbage collection run the network is shut down.</para>
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      </listitem>
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      <listitem>
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        <para>When the last VM on a network is destroyed, the network garbage collector checks if
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          the network offering associated with the network is persistent, and shuts down the network
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          only if it is non-persistent.</para>
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      </listitem>
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    </itemizedlist>
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  </section>
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  <section id="set-up-persistent-network">
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    <title>Creating a Persistent Guest Network</title>
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    <para>To create a persistent network, perform the following:</para>
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    <orderedlist>
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      <listitem>
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        <para>Create a network offering with the Persistent option enabled.</para>
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        <para condition="admin">See <xref linkend="creating-network-offerings"/>.</para>
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        <para condition="install">See the Administration Guide.</para>
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      </listitem>
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      <listitem>
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        <para>Select Network from the left navigation pane.</para>
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      </listitem>
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      <listitem>
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        <para>Select the guest network that you want to offer this network service to.</para>
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      </listitem>
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      <listitem>
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        <para>Click the Edit button.</para>
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      </listitem>
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      <listitem>
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        <para>From the Network Offering drop-down, select the persistent network offering you have
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          just created.</para>
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      </listitem>
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      <listitem>
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        <para>Click OK.</para>
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      </listitem>
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    </orderedlist>
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  </section>
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</section>
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