docs/en-US/gslb.xml - cloudstack - Git at Google

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 <section id="gslb">
   <title>Global Server Load Balancing Support</title>
   <para>&PRODUCT; supports Global Server Load Balancing (GSLB) functionalities to provide business
     continuity, and enable seamless resource movement within a &PRODUCT; environment. &PRODUCT;
     achieve this by extending its functionality of integrating with NetScaler Application Delivery
     Controller (ADC), which also provides various GSLB capabilities, such as disaster recovery and
     load balancing. The DNS redirection technique is used to achieve GSLB in &PRODUCT;. </para>
   <para>In order to support his functionality, region level services and service provider are
     introduced. A new service 'GSLB' is introduced as a region level service. The GSLB service
     provider is introduced that will provider the GSLB service. Currently, NetScaler is the
     supported GSLB provider in &PRODUCT;. GSLB functionality works in an Active-Active data center
     environment. </para>
   <section id="about-gslb">
     <title>About Global Server Load Balancing</title>
     <para>Global Server Load Balancing (GSLB) is an extension of load balancing functionality, which
       is highly efficient in avoiding downtime. Based on the nature of deployment, GSLB represents a
       set of technologies that is used for various purposes, such as load sharing, disaster
       recovery, performance, and legal obligations. With GSLB, workloads can be distributed across
       multiple data centers situated at geographically separated locations. GSLB can also provide an
       alternate location for accessing a resource in the event of a failure, or to provide a means
       of shifting traffic easily to simplify maintenance, or both.</para>
   </section>
   <section id="prereq-gslb">
     <title>Prerequisites and Guidelines</title>
     <itemizedlist>
       <listitem>
         <para>The GSLB functionality is supported both Basic and Advanced zones.</para>
       </listitem>
       <listitem>
         <para>GSLB is added as a new network service.</para>
       </listitem>
       <listitem>
         <para>GSLB service provider can be added to a physical network in a zone.</para>
       </listitem>
       <listitem>
         <para>The admin is allowed to enable or disable GSLB functionality at region level.</para>
       </listitem>
       <listitem>
         <para>The admin is allowed to configure a zone as GSLB capable or enabled. </para>
         <para>A zone shall be considered as GSLB capable only if a GSLB service provider is
           provisioned in the zone.</para>
       </listitem>
       <listitem>
         <para>When users have VMs deployed in multiple availability zones which are GSLB enabled,
           user is allowed to use the GSLB functionality to load balance traffic across the VMs in
           multiple zones.</para>
       </listitem>
       <listitem>
         <para>The users are allowed to use GSLB to load balance across the VMs across zones in a
           region only if the admin has enabled GSLB in that region. </para>
       </listitem>
       <listitem>
         <para>The users are allowed to load balance traffic across the availability zones in the
           same region or different regions.</para>
       </listitem>
       <listitem>
         <para>The admin is allowed to configure DNS name for the entire cloud.</para>
       </listitem>
       <listitem>
         <para>The users can specify an unique name, across the cloud, for a globally load balanced
           service. The provided name will be used as the domain under the DNS name associated with
           the cloud.</para>
         <para>The user-provided name along with the admin-provided DNS name is used to produce a
           globally resolvable FQDN for the globally load balanced service of the user. For example,
           if the admin has configured xyztelco.com as the DNS name for the cloud, and user specifies
           'foo' for the GSLB virtual service, then the FQDN name of the GSLB virtual service is
           foo.xyztelco.com.</para>
       </listitem>
       <listitem>
         <para>While setting up GSLB, users can select a load balancing method, such as round robin
           or least RTT, that would be the load balance traffic used across the zones that are part
           of GSLB.</para>
       </listitem>
       <listitem>
         <para>The user shall be able to set weight to zone-level virtual server. Weight shall be
           considered by the load balancing method is distributing the traffic.</para>
       </listitem>
       <listitem>
         <para>The GSLB functionality shall support session persistence, where series of client
           requests for particular domain name is sent to a virtual server on the same zone. </para>
         <para>Statistics is collected from each GSLB virtual server.</para>
       </listitem>
     </itemizedlist>
   </section>
   <section id="gslb-add">
     <title>Adding a GSLB Rule</title>
     <orderedlist>
       <listitem>
         <para>Log in to the &PRODUCT; UI as administrator.</para>
       </listitem>
       <listitem>
         <para>In the left navigation pane, click Region.</para>
       </listitem>
       <listitem>
         <para>Select the region for which you want to create a GSLB rule.</para>
       </listitem>
       <listitem>
         <para>In the Details tab, click View GSLB.</para>
       </listitem>
       <listitem>
         <para>Click Add GSLB.</para>
         <para>The Add GSLB page is displayed as follows:</para>
         <mediaobject>
           <imageobject>
             <imagedata fileref="./images/add-gslb.png"/>
           </imageobject>
           <textobject>
             <phrase>gslb-add.png: adding a gslb rule</phrase>
           </textobject>
         </mediaobject>
       </listitem>
       <listitem>
         <para>Specify the following:</para>
         <itemizedlist>
           <listitem>
             <para><emphasis role="bold">Name</emphasis>: Name for the GSLB rule.</para>
           </listitem>
           <listitem>
             <para><emphasis role="bold">Description</emphasis>: (Optional) A short description of
               the GSLB rule that can be displayed to users.</para>
           </listitem>
           <listitem>
             <para><emphasis role="bold">GSLB Domain Name</emphasis>: A preferred domain name for the
               service.</para>
           </listitem>
           <listitem>
             <para><emphasis role="bold">Algorithm</emphasis>: (Optional) The algorithm to use to
               load balance the traffic across the zones. The options are Round Robin, Least
               Connection, and Proximity.</para>
           </listitem>
           <listitem>
             <para><emphasis role="bold">Service Type</emphasis>: The transport protocol to use for
               GSLB. The options are TCP and UDP.</para>
           </listitem>
           <listitem>
             <para><emphasis role="bold">Domain</emphasis>: (Optional) The domain for which you want
               to create the GSLB rule.</para>
           </listitem>
           <listitem>
             <para><emphasis role="bold">Account</emphasis>: (Optional) The account on which you want
               to apply the GSLB rule.</para>
           </listitem>
         </itemizedlist>
       </listitem>
       <listitem>
         <para>Click OK to confirm.</para>
       </listitem>
     </orderedlist>
   </section>
   <section id="assign-lb-gslb">
     <title>Assigning Load Balancing Rules to GSLB</title>
     <para/>
   </section>
   <section id="concept-gslb">
     <title>How Does GSLB Works in &PRODUCT;?</title>
     <para>The following is an illustrated conceptual model of how GLSB functionality is provided in
       &PRODUCT;: An organization, xyztelco, has set up a public cloud that spans two zones, Zone-1
       and Zone-2, across geographically separated data centers that are managed by &PRODUCT;.
       Tenant-A of the cloud launches a highly available solution by using xyztelco cloud. For that
       purpose, they launch two instances each in both the zones: VM1 and VM2 in Zone-1 and VM5 and
       VM6 in Zone-2. Tenant-A acquires a public IP, IP-1 in Zone-1, and configures a load balancer
       rule to load balance the traffic between VM1 and VM2 instances. &PRODUCT; orchestrates setting
       up a virtual server on the LB service provider in Zone-1. Virtual server 1 that is set up on
       the LB service provider in Zone-1 represents a publicly accessible virtual server that client
       reaches at IP-1. The client traffic to virtual server 1 at IP-1 will be load balanced across
       VM1 and VM2 instances. </para>
     <para>Tenant-A acquires another public IP, IP-2 in Zone-2 and sets up a load balancer rule to
       load balance the traffic between VM5 and VM6 instances. Similarly in Zone-2, &PRODUCT;
       orchestrates setting up a virtual server on the LB service provider. Virtual server 2 that is
       setup on the LB service provider in Zone-2 represents a publicly accessible virtual server
       that client reaches at IP-2. The client traffic that reaches virtual server 2 at IP-2 is load
       balanced across VM5 and VM6 instances. At this point Tenant-A has the service enabled in both
       the zones, but has no means to set up a disaster recovery plan if one of the zone fails.
       Additionally, there is no way for Tenant-A to load balance the traffic intelligently to one of
       the zones based on load, proximity and so on. The cloud administrator of xyztelco provisions a
       GSLB service provider to both the zones. A GSLB provider is typically an ADC that has the
       ability to act as an ADNS (Authoritative Domain Name Server) and has the mechanism to monitor
       health of virtual servers both at local and remote sites. The cloud admin enables GSLB as a
       service to the tenants that use zones 1 and 2. </para>
     <mediaobject>
       <imageobject>
         <imagedata fileref="./images/gslb.png"/>
       </imageobject>
       <textobject>
         <phrase>gslb.png: GSLB architecture</phrase>
       </textobject>
     </mediaobject>
     <para>Tenant-A wishes to leverage the GSLB service provided by the xyztelco cloud. Tenant-A
       configures a GSLB rule to load balance traffic across virtual server 1 at Zone-1 and virtual
       server 2 at Zone-2. The domain name is provided as A.xyztelco.com. &PRODUCT; orchestrates
       setting up GSLB virtual server 1 on the GSLB service provider at Zone-1. &PRODUCT; binds
       virtual server 1 of Zone-1 and virtual server 2 of Zone-2 to GLSB virtual server 1. GSLB
       virtual server 1 is configured to start monitoring the health of virtual server 1 and 2 in
       Zone-1. &PRODUCT; will also orchestrate setting up GSLB virtual server 2 on GSLB service
       provider at Zone-2. &PRODUCT; will bind virtual server 1 of Zone-1 and virtual server 2 of
       Zone-2 to GLSB virtual server 2. GSLB virtual server 2 is configured to start monitoring the
       health of virtual server 1 and 2. &PRODUCT; will bind the domain A.xyztelco.com to both the
       GSLB virtual server 1 and 2. At this point, Tenant-A service will be globally reachable at
       A.xyztelco.com. The private DNS server for the domain xyztelcom.com is configured by the admin
       out-of-band to resolve the domain A.xyztelco.com to the GSLB providers at both the zones,
       which are configured as ADNS for the domain A.xyztelco.com. A client when sends a DNS request
       to resolve A.xyztelcom.com, will eventually get DNS delegation to the address of GSLB
       providers at Zone 1 and 2. A client DNS request will be received by the GSLB provider. The
       GSLB provider, depending on the domain for which it needs to resolve, will pick up the GSLB
       virtual server associated with the domain. Depending on the health of the virtual servers
       being load balanced, DNS request for the domain will be resolved to the public IP associated
       with the selected virtual server.</para>
   </section>
   <section id="limitation-gslb">
     <title>Known Limitation</title>
     <para>Currently, &PRODUCT; does not support orchestration of services across the zones. The
       notion of services and service providers in region are to be introduced.</para>
   </section>
 </section>
	<?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="gslb">
	<title>Global Server Load Balancing Support</title>
	<para>&PRODUCT; supports Global Server Load Balancing (GSLB) functionalities to provide business
	continuity, and enable seamless resource movement within a &PRODUCT; environment. &PRODUCT;
	achieve this by extending its functionality of integrating with NetScaler Application Delivery
	Controller (ADC), which also provides various GSLB capabilities, such as disaster recovery and
	load balancing. The DNS redirection technique is used to achieve GSLB in &PRODUCT;. </para>
	<para>In order to support his functionality, region level services and service provider are
	introduced. A new service 'GSLB' is introduced as a region level service. The GSLB service
	provider is introduced that will provider the GSLB service. Currently, NetScaler is the
	supported GSLB provider in &PRODUCT;. GSLB functionality works in an Active-Active data center
	environment. </para>
	<section id="about-gslb">
	<title>About Global Server Load Balancing</title>
	<para>Global Server Load Balancing (GSLB) is an extension of load balancing functionality, which
	is highly efficient in avoiding downtime. Based on the nature of deployment, GSLB represents a
	set of technologies that is used for various purposes, such as load sharing, disaster
	recovery, performance, and legal obligations. With GSLB, workloads can be distributed across
	multiple data centers situated at geographically separated locations. GSLB can also provide an
	alternate location for accessing a resource in the event of a failure, or to provide a means
	of shifting traffic easily to simplify maintenance, or both.</para>
	</section>
	<section id="prereq-gslb">
	<title>Prerequisites and Guidelines</title>
	<itemizedlist>
	<listitem>
	<para>The GSLB functionality is supported both Basic and Advanced zones.</para>
	</listitem>
	<listitem>
	<para>GSLB is added as a new network service.</para>
	</listitem>
	<listitem>
	<para>GSLB service provider can be added to a physical network in a zone.</para>
	</listitem>
	<listitem>
	<para>The admin is allowed to enable or disable GSLB functionality at region level.</para>
	</listitem>
	<listitem>
	<para>The admin is allowed to configure a zone as GSLB capable or enabled. </para>
	<para>A zone shall be considered as GSLB capable only if a GSLB service provider is
	provisioned in the zone.</para>
	</listitem>
	<listitem>
	<para>When users have VMs deployed in multiple availability zones which are GSLB enabled,
	user is allowed to use the GSLB functionality to load balance traffic across the VMs in
	multiple zones.</para>
	</listitem>
	<listitem>
	<para>The users are allowed to use GSLB to load balance across the VMs across zones in a
	region only if the admin has enabled GSLB in that region. </para>
	</listitem>
	<listitem>
	<para>The users are allowed to load balance traffic across the availability zones in the
	same region or different regions.</para>
	</listitem>
	<listitem>
	<para>The admin is allowed to configure DNS name for the entire cloud.</para>
	</listitem>
	<listitem>
	<para>The users can specify an unique name, across the cloud, for a globally load balanced
	service. The provided name will be used as the domain under the DNS name associated with
	the cloud.</para>
	<para>The user-provided name along with the admin-provided DNS name is used to produce a
	globally resolvable FQDN for the globally load balanced service of the user. For example,
	if the admin has configured xyztelco.com as the DNS name for the cloud, and user specifies
	'foo' for the GSLB virtual service, then the FQDN name of the GSLB virtual service is
	foo.xyztelco.com.</para>
	</listitem>
	<listitem>
	<para>While setting up GSLB, users can select a load balancing method, such as round robin
	or least RTT, that would be the load balance traffic used across the zones that are part
	of GSLB.</para>
	</listitem>
	<listitem>
	<para>The user shall be able to set weight to zone-level virtual server. Weight shall be
	considered by the load balancing method is distributing the traffic.</para>
	</listitem>
	<listitem>
	<para>The GSLB functionality shall support session persistence, where series of client
	requests for particular domain name is sent to a virtual server on the same zone. </para>
	<para>Statistics is collected from each GSLB virtual server.</para>
	</listitem>
	</itemizedlist>
	</section>
	<section id="gslb-add">
	<title>Adding a GSLB Rule</title>
	<orderedlist>
	<listitem>
	<para>Log in to the &PRODUCT; UI as administrator.</para>
	</listitem>
	<listitem>
	<para>In the left navigation pane, click Region.</para>
	</listitem>
	<listitem>
	<para>Select the region for which you want to create a GSLB rule.</para>
	</listitem>
	<listitem>
	<para>In the Details tab, click View GSLB.</para>
	</listitem>
	<listitem>
	<para>Click Add GSLB.</para>
	<para>The Add GSLB page is displayed as follows:</para>
	<mediaobject>
	<imageobject>
	<imagedata fileref="./images/add-gslb.png"/>
	</imageobject>
	<textobject>
	<phrase>gslb-add.png: adding a gslb rule</phrase>
	</textobject>
	</mediaobject>
	</listitem>
	<listitem>
	<para>Specify the following:</para>
	<itemizedlist>
	<listitem>
	<para><emphasis role="bold">Name</emphasis>: Name for the GSLB rule.</para>
	</listitem>
	<listitem>
	<para><emphasis role="bold">Description</emphasis>: (Optional) A short description of
	the GSLB rule that can be displayed to users.</para>
	</listitem>
	<listitem>
	<para><emphasis role="bold">GSLB Domain Name</emphasis>: A preferred domain name for the
	service.</para>
	</listitem>
	<listitem>
	<para><emphasis role="bold">Algorithm</emphasis>: (Optional) The algorithm to use to
	load balance the traffic across the zones. The options are Round Robin, Least
	Connection, and Proximity.</para>
	</listitem>
	<listitem>
	<para><emphasis role="bold">Service Type</emphasis>: The transport protocol to use for
	GSLB. The options are TCP and UDP.</para>
	</listitem>
	<listitem>
	<para><emphasis role="bold">Domain</emphasis>: (Optional) The domain for which you want
	to create the GSLB rule.</para>
	</listitem>
	<listitem>
	<para><emphasis role="bold">Account</emphasis>: (Optional) The account on which you want
	to apply the GSLB rule.</para>
	</listitem>
	</itemizedlist>
	</listitem>
	<listitem>
	<para>Click OK to confirm.</para>
	</listitem>
	</orderedlist>
	</section>
	<section id="assign-lb-gslb">
	<title>Assigning Load Balancing Rules to GSLB</title>
	<para/>
	</section>
	<section id="concept-gslb">
	<title>How Does GSLB Works in &PRODUCT;?</title>
	<para>The following is an illustrated conceptual model of how GLSB functionality is provided in
	&PRODUCT;: An organization, xyztelco, has set up a public cloud that spans two zones, Zone-1
	and Zone-2, across geographically separated data centers that are managed by &PRODUCT;.
	Tenant-A of the cloud launches a highly available solution by using xyztelco cloud. For that
	purpose, they launch two instances each in both the zones: VM1 and VM2 in Zone-1 and VM5 and
	VM6 in Zone-2. Tenant-A acquires a public IP, IP-1 in Zone-1, and configures a load balancer
	rule to load balance the traffic between VM1 and VM2 instances. &PRODUCT; orchestrates setting
	up a virtual server on the LB service provider in Zone-1. Virtual server 1 that is set up on
	the LB service provider in Zone-1 represents a publicly accessible virtual server that client
	reaches at IP-1. The client traffic to virtual server 1 at IP-1 will be load balanced across
	VM1 and VM2 instances. </para>
	<para>Tenant-A acquires another public IP, IP-2 in Zone-2 and sets up a load balancer rule to
	load balance the traffic between VM5 and VM6 instances. Similarly in Zone-2, &PRODUCT;
	orchestrates setting up a virtual server on the LB service provider. Virtual server 2 that is
	setup on the LB service provider in Zone-2 represents a publicly accessible virtual server
	that client reaches at IP-2. The client traffic that reaches virtual server 2 at IP-2 is load
	balanced across VM5 and VM6 instances. At this point Tenant-A has the service enabled in both
	the zones, but has no means to set up a disaster recovery plan if one of the zone fails.
	Additionally, there is no way for Tenant-A to load balance the traffic intelligently to one of
	the zones based on load, proximity and so on. The cloud administrator of xyztelco provisions a
	GSLB service provider to both the zones. A GSLB provider is typically an ADC that has the
	ability to act as an ADNS (Authoritative Domain Name Server) and has the mechanism to monitor
	health of virtual servers both at local and remote sites. The cloud admin enables GSLB as a
	service to the tenants that use zones 1 and 2. </para>
	<mediaobject>
	<imageobject>
	<imagedata fileref="./images/gslb.png"/>
	</imageobject>
	<textobject>
	<phrase>gslb.png: GSLB architecture</phrase>
	</textobject>
	</mediaobject>
	<para>Tenant-A wishes to leverage the GSLB service provided by the xyztelco cloud. Tenant-A
	configures a GSLB rule to load balance traffic across virtual server 1 at Zone-1 and virtual
	server 2 at Zone-2. The domain name is provided as A.xyztelco.com. &PRODUCT; orchestrates
	setting up GSLB virtual server 1 on the GSLB service provider at Zone-1. &PRODUCT; binds
	virtual server 1 of Zone-1 and virtual server 2 of Zone-2 to GLSB virtual server 1. GSLB
	virtual server 1 is configured to start monitoring the health of virtual server 1 and 2 in
	Zone-1. &PRODUCT; will also orchestrate setting up GSLB virtual server 2 on GSLB service
	provider at Zone-2. &PRODUCT; will bind virtual server 1 of Zone-1 and virtual server 2 of
	Zone-2 to GLSB virtual server 2. GSLB virtual server 2 is configured to start monitoring the
	health of virtual server 1 and 2. &PRODUCT; will bind the domain A.xyztelco.com to both the
	GSLB virtual server 1 and 2. At this point, Tenant-A service will be globally reachable at
	A.xyztelco.com. The private DNS server for the domain xyztelcom.com is configured by the admin
	out-of-band to resolve the domain A.xyztelco.com to the GSLB providers at both the zones,
	which are configured as ADNS for the domain A.xyztelco.com. A client when sends a DNS request
	to resolve A.xyztelcom.com, will eventually get DNS delegation to the address of GSLB
	providers at Zone 1 and 2. A client DNS request will be received by the GSLB provider. The
	GSLB provider, depending on the domain for which it needs to resolve, will pick up the GSLB
	virtual server associated with the domain. Depending on the health of the virtual servers
	being load balanced, DNS request for the domain will be resolved to the public IP associated
	with the selected virtual server.</para>
	</section>
	<section id="limitation-gslb">
	<title>Known Limitation</title>
	<para>Currently, &PRODUCT; does not support orchestration of services across the zones. The
	notion of services and service providers in region are to be introduced.</para>
	</section>
	</section>