mirror of
https://github.com/apache/cloudstack.git
synced 2025-11-03 04:12:31 +01:00
104 lines
6.2 KiB
XML
104 lines
6.2 KiB
XML
<?xml version='1.0' encoding='utf-8' ?>
|
|
<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
|
|
<!ENTITY % BOOK_ENTITIES SYSTEM "cloudstack.ent">
|
|
%BOOK_ENTITIES;
|
|
]>
|
|
<!-- Licensed to the Apache Software Foundation (ASF) under one
|
|
or more contributor license agreements. See the NOTICE file
|
|
distributed with this work for additional information
|
|
regarding copyright ownership. The ASF licenses this file
|
|
to you under the Apache License, Version 2.0 (the
|
|
"License"); you may not use this file except in compliance
|
|
with the License. You may obtain a copy of the License at
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
Unless required by applicable law or agreed to in writing,
|
|
software distributed under the License is distributed on an
|
|
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
|
|
KIND, either express or implied. See the License for the
|
|
specific language governing permissions and limitations
|
|
under the License.
|
|
-->
|
|
<section id="elastic-ip">
|
|
<title>About Elastic IP</title>
|
|
<para>Elastic IP (EIP) addresses are the IP addresses that are associated with an account, and act
|
|
as static IP addresses. The account owner has the complete control over the Elastic IP addresses
|
|
that belong to the account. As an account owner, you can allocate an Elastic IP to a VM of your
|
|
choice from the EIP pool of your account. Later if required you can reassign the IP address to a
|
|
different VM. This feature is extremely helpful during VM failure. Instead of replacing the VM
|
|
which is down, the IP address can be reassigned to a new VM in your account. </para>
|
|
<para>Similar to the public IP address, Elastic IP addresses are mapped to their associated
|
|
private IP addresses by using StaticNAT. The EIP service is equipped with StaticNAT (1:1)
|
|
service in an EIP-enabled basic zone. The default network offering,
|
|
DefaultSharedNetscalerEIPandELBNetworkOffering, provides your network with EIP and ELB network
|
|
services if a NetScaler device is deployed in your zone. Consider the following illustration for
|
|
more details.</para>
|
|
<mediaobject>
|
|
<imageobject>
|
|
<imagedata fileref="./images/eip-ns-basiczone.png"/>
|
|
</imageobject>
|
|
<textobject>
|
|
<phrase>eip-ns-basiczone.png: Elastic IP in a NetScaler-enabled Basic Zone.</phrase>
|
|
</textobject>
|
|
</mediaobject>
|
|
<para>In the illustration, a NetScaler appliance is the default entry or exit point for the
|
|
&PRODUCT; instances, and firewall is the default entry or exit point for the rest of the data
|
|
center. Netscaler provides LB services and staticNAT service to the guest networks. The guest
|
|
traffic in the pods and the Management Server are on different subnets / VLANs. The policy-based
|
|
routing in the data center core switch sends the public traffic through the NetScaler, whereas
|
|
the rest of the data center goes through the firewall. </para>
|
|
<para>The EIP work flow is as follows:</para>
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>When a user VM is deployed, a public IP is automatically acquired from the pool of
|
|
public IPs configured in the zone. This IP is owned by the VM's account.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>Each VM will have its own private IP. When the user VM starts, Static NAT is provisioned
|
|
on the NetScaler device by using the Inbound Network Address Translation (INAT) and Reverse
|
|
NAT (RNAT) rules between the public IP and the private IP.</para>
|
|
<note>
|
|
<para>Inbound NAT (INAT) is a type of NAT supported by NetScaler, in which the destination
|
|
IP address is replaced in the packets from the public network, such as the Internet, with
|
|
the private IP address of a VM in the private network. Reverse NAT (RNAT) is a type of NAT
|
|
supported by NetScaler, in which the source IP address is replaced in the packets
|
|
generated by a VM in the private network with the public IP address.</para>
|
|
</note>
|
|
</listitem>
|
|
<listitem>
|
|
<para>This default public IP will be released in two cases:</para>
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>When the VM is stopped. When the VM starts, it again receives a new public IP, not
|
|
necessarily the same one allocated initially, from the pool of Public IPs.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>The user acquires a public IP (Elastic IP). This public IP is associated with the
|
|
account, but will not be mapped to any private IP. However, the user can enable Static
|
|
NAT to associate this IP to the private IP of a VM in the account. The Static NAT rule
|
|
for the public IP can be disabled at any time. When Static NAT is disabled, a new public
|
|
IP is allocated from the pool, which is not necessarily be the same one allocated
|
|
initially.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</listitem>
|
|
</itemizedlist>
|
|
<para>For the deployments where public IPs are limited resources, you have the flexibility to
|
|
choose not to allocate a public IP by default. You can use the Associate Public IP option to
|
|
turn on or off the automatic public IP assignment in the EIP-enabled Basic zones. If you turn
|
|
off the automatic public IP assignment while creating a network offering, only a private IP is
|
|
assigned to a VM when the VM is deployed with that network offering. Later, the user can acquire
|
|
an IP for the VM and enable static NAT.</para>
|
|
<para condition="admin">For more information on the Associate Public IP option, see <xref
|
|
linkend="creating-network-offerings"/>.</para>
|
|
<para condition="install">For more information on the Associate Public IP option, see the
|
|
Administration Guide.</para>
|
|
<note>
|
|
<para>The Associate Public IP feature is designed only for use with user VMs. The System VMs
|
|
continue to get both public IP and private by default, irrespective of the network offering
|
|
configuration.</para>
|
|
</note>
|
|
<para>New deployments which use the default shared network offering with EIP and ELB services to
|
|
create a shared network in the Basic zone will continue allocating public IPs to each user
|
|
VM.</para>
|
|
</section>
|