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Overview of Setting Up Networking for Users
-------------------------------------------

People using cloud infrastructure have a variety of needs and
preferences when it comes to the networking services provided by the
cloud. As a CloudStack administrator, you can do the following things to
set up networking for your users:

-  Set up physical networks in zones

-  Set up several different providers for the same service on a single
   physical network (for example, both Cisco and Juniper firewalls)

-  Bundle different types of network services into network offerings, so
   users can choose the desired network services for any given virtual
   machine

-  Add new network offerings as time goes on so end users can upgrade to
   a better class of service on their network

-  Provide more ways for a network to be accessed by a user, such as
   through a project of which the user is a member


About Virtual Networks
---------------------------

A virtual network is a logical construct that enables multi-tenancy on a
single physical network. In CloudStack a virtual network can be shared
or isolated.


Isolated Networks
~~~~~~~~~~~~~~~~~

An isolated network can be accessed only by virtual machines of a single
account. Isolated networks have the following properties.

-  Resources such as VLAN are allocated and garbage collected
   dynamically

-  There is one network offering for the entire network

-  The network offering can be upgraded or downgraded but it is for the
   entire network

For more information, see `“Configure Guest Traffic in an Advanced Zone” 
<networking2.html#configure-guest-traffic-in-an-advanced-zone>`_.


Shared Networks
~~~~~~~~~~~~~~~

A shared network can be accessed by virtual machines that belong to many
different accounts. Network Isolation on shared networks is accomplished
by using techniques such as security groups, which is supported only in
Basic zones in CloudStack 3.0.3 and later versions.

-  Shared Networks are created by the administrator

-  Shared Networks can be designated to a certain domain

-  Shared Network resources such as VLAN and physical network that it
   maps to are designated by the administrator

-  Shared Networks can be isolated by security groups

-  Public Network is a shared network that is not shown to the end users

-  Source NAT per zone is not supported in Shared Network when the
   service provider is virtual router. However, Source NAT per account
   is supported. For information, see `“Configuring a Shared Guest 
   Network” <networking2.html#configuring-a-shared-guest-network>`_.


L2 Networks
~~~~~~~~~~~

L2 networks provide network isolation without any other services.  This
means that there will be no virtual router.  It is assumed that the end
user will have their own IPAM in place, or that they will statically assign 
IP addresses.

-  L2 networks can be created by the end users, however network offerings
   which allow the network creator to specify a VLAN can only be created
   by the root admins.

-  CloudStack does not assign IP addresses to VMs.

-  Userdata and metadata can be passed to the VM using a config drive
   (which must be enabled in the network service offering)

Example GUI dialog box (for a regular user account) is shown below:

|L2-networks-gui.JPG|


Runtime Allocation of Virtual Network Resources
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When you define a new virtual network, all your settings for that
network are stored in CloudStack. The actual network resources are
activated only when the first virtual machine starts in the network.
When all virtual machines have left the virtual network, the network
resources are garbage collected so they can be allocated again. This
helps to conserve network resources.


Network Service Providers
-------------------------

.. note:: 
   For the most up-to-date list of supported network service providers, 
   see the CloudStack UI or call `listNetworkServiceProviders`.

A service provider (also called a network element) is hardware or
virtual appliance that makes a network service possible; for example, a
firewall appliance can be installed in the cloud to provide firewall
service. On a single network, multiple providers can provide the same
network service. For example, a firewall service may be provided by
Cisco or Juniper devices in the same physical network.

You can have multiple instances of the same service provider in a
network (say, more than one Juniper SRX device).

If different providers are set up to provide the same service on the
network, the administrator can create network offerings so users can
specify which network service provider they prefer (along with the other
choices offered in network offerings). Otherwise, CloudStack will choose
which provider to use whenever the service is called for.

*Supported Network Service Providers*

CloudStack ships with an internal list of the supported service
providers, and you can choose from this list when creating a network
offering.

.. cssclass:: table-striped table-bordered table-hover

+----------------------+-----------+------------+----------+-------------+-------------+
|                      | Virtual   | Citrix     | Juniper  | F5 BigIP    | Host based  |
|                      | Router    | NetScaler  | SRX      |             | (KVM/Xen)   |
+======================+===========+============+==========+=============+=============+
| Remote Access VPN    | Yes       | No         | No       | No          | No          |
+----------------------+-----------+------------+----------+-------------+-------------+
| DNS/DHCP/User Data   | Yes       | No         | No       | No          | No          |
+----------------------+-----------+------------+----------+-------------+-------------+
| Firewall             | Yes       | No         | Yes      | No          | No          |
+----------------------+-----------+------------+----------+-------------+-------------+
| Load Balancing       | Yes       | Yes        | No       | Yes         | No          |
+----------------------+-----------+------------+----------+-------------+-------------+
| Elastic IP           | No        | Yes        | No       | No          | No          |
+----------------------+-----------+------------+----------+-------------+-------------+
| Elastic LB           | No        | Yes        | No       | No          | No          |
+----------------------+-----------+------------+----------+-------------+-------------+
| Source NAT           | Yes       | No         | Yes      | No          | No          |
+----------------------+-----------+------------+----------+-------------+-------------+
| Static NAT           | Yes       | Yes        | Yes      | No          | No          |
+----------------------+-----------+------------+----------+-------------+-------------+
| Port Forwarding      | Yes       | No         | Yes      | No          | No          |
+----------------------+-----------+------------+----------+-------------+-------------+


Network Offerings
-----------------

.. note:: 
   For the most up-to-date list of supported network services, see the 
   CloudStack UI or call listNetworkServices.

A network offering is a named set of network services, such as:

-  DHCP

-  DNS

-  Source NAT

-  Static NAT

-  Port Forwarding

-  Load Balancing

-  Firewall

-  VPN

-  (Optional) Name one of several available providers to use for a given
   service, such as Juniper for the firewall

-  (Optional) Network tag to specify which physical network to use

When creating a new VM, the user chooses one of the available network
offerings, and that determines which network services the VM can use.

The CloudStack administrator can create any number of custom network
offerings, in addition to the default network offerings provided by
CloudStack. By creating multiple custom network offerings, you can set
up your cloud to offer different classes of service on a single
multi-tenant physical network. For example, while the underlying
physical wiring may be the same for two tenants, tenant A may only need
simple firewall protection for their website, while tenant B may be
running a web server farm and require a scalable firewall solution, load
balancing solution, and alternate networks for accessing the database
backend.

.. note:: 
   If you create load balancing rules while using a network service 
   offering that includes an external load balancer device such as 
   NetScaler, and later change the network service offering to one that 
   uses the CloudStack virtual router, you must create a firewall rule 
   on the virtual router for each of your existing load balancing rules 
   so that they continue to function.

When creating a new virtual network, the CloudStack administrator
chooses which network offering to enable for that network. Each virtual
network is associated with one network offering. A virtual network can
be upgraded or downgraded by changing its associated network offering.
If you do this, be sure to reprogram the physical network to match.

CloudStack also has internal network offerings for use by CloudStack
system VMs. These network offerings are not visible to users but can be
modified by administrators.


Creating a New Network Offering
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To create a network offering:

#. Log in with admin privileges to the CloudStack UI.

#. In the left navigation bar, click Service Offerings.

#. In Select Offering, choose Network Offering.

#. Click Add Network Offering.

#. In the dialog, make the following choices:

   -  **Name**. Any desired name for the network offering.

   -  **Description**. A short description of the offering that can be
      displayed to users.

   -  **Network Rate**. Allowed data transfer rate in MB per second.

   -  **Guest Type**. Choose whether the guest network is isolated or
      shared.

      For a description of this term, see `“About Virtual
      Networks” <#about-virtual-networks>`_.

   -  **Persistent**. Indicate whether the guest network is persistent
      or not. The network that you can provision without having to
      deploy a VM on it is termed persistent network. For more
      information, see `“Persistent
      Networks” <networking2.html#persistent-networks>`_.

   -  **Specify VLAN**. (Isolated guest networks only) Indicate whether
      a VLAN could be specified when this offering is used. If you
      select this option and later use this network offering while
      creating a VPC tier or an isolated network, you will be able to
      specify a VLAN ID for the network you create.

   -  **VPC**. This option indicate whether the guest network is Virtual
      Private Cloud-enabled. A Virtual Private Cloud (VPC) is a private,
      isolated part of CloudStack. A VPC can have its own virtual
      network topology that resembles a traditional physical network.
      For more information on VPCs, see `“About Virtual
      Private Clouds” <networking2.html#about-virtual-private-clouds>`_.

   -  **Supported Services**. Select one or more of the possible network
      services. For some services, you must also choose the service
      provider; for example, if you select Load Balancer, you can choose
      the CloudStack virtual router or any other load balancers that
      have been configured in the cloud. Depending on which services you
      choose, additional fields may appear in the rest of the dialog
      box.

      Based on the guest network type selected, you can see the
      following supported services:

      .. cssclass:: table-striped table-bordered table-hover
      
      =================== ============================================================================ ============= =============
      Supported Services  Description                                                                  Isolated      Shared   
      =================== ============================================================================ ============= =============
      DHCP                For more information, see `“DNS and DHCP” <networking2.html#dns-and-dhcp>`_. Supported     Supported
      DNS                 For more information, see `“DNS and DHCP” <networking2.html#dns-and-dhcp>`_. Supported     Supported
      Load Balancer       If you select Load Balancer, you can choose the CloudStack virtual           Supported     Supported
                          router or any other load balancers that have been configured in
                          the cloud.
      Firewall            For more information, see the Administration Guide.                          Supported     Supported
      Source NAT          If you select Source NAT, you can choose the CloudStack virtual              Supported     Supported
                          router or any other Source NAT providers that have been configured
                          in the cloud.
      Static NAT          If you select Static NAT, you can choose the CloudStack virtual              Supported     Supported
                          router or any other Static NAT providers that have been configured
                          in the cloud.
      Port Forwarding     If you select Port Forwarding, you can choose the CloudStack                 Supported     Not Supported
                          virtual router or any other Port Forwarding providers that have
                          been configured in the cloud.
      VPN                 For more information, see `“Remote Access                                    Supported     Not Supported
                          VPN” <networking2.html#remote-access-vpn>`_.
      User Data           For more information, see `“User Data and Meta                               Not Supported Supported
                          Data” <api.html#user-data-and-meta-data>`_.
      Network ACL         For more information, see `“Configuring Network Access                       Supported     Not Supported
                          Control List” <networking2.html#configuring-network-access-control-list>`_.
      Security Groups     For more information, see `“Adding a Security                                Not Supported Supported
                          Group” <networking2.html#adding-a-security-group>`_.
      =================== ============================================================================ ============= =============


   -  **System Offering**. If the service provider for any of the
      services selected in Supported Services is a virtual router, the
      System Offering field appears. Choose the system service offering
      that you want virtual routers to use in this network. For example,
      if you selected Load Balancer in Supported Services and selected a
      virtual router to provide load balancing, the System Offering
      field appears so you can choose between the CloudStack default
      system service offering and any custom system service offerings
      that have been defined by the CloudStack root administrator.

      For more information, see `“System Service Offerings” 
      <service_offerings.html#system-service-offerings>`_.

   -  **LB Isolation**: Specify what type of load balancer isolation you
      want for the network: Shared or Dedicated.

      -  **Dedicated**: If you select dedicated LB isolation, a dedicated
         load balancer device is assigned for the network from the pool of
         dedicated load balancer devices provisioned in the zone. If no
         sufficient dedicated load balancer devices are available in the
         zone, network creation fails. Dedicated device is a good choice
         for the high-traffic networks that make full use of the device's
         resources.

      -  **Shared**: If you select shared LB isolation, a shared load
         balancer device is assigned for the network from the pool of
         shared load balancer devices provisioned in the zone. While
         provisioning CloudStack picks the shared load balancer device that
         is used by the least number of accounts. Once the device reaches
         its maximum capacity, the device will not be allocated to a new
         account.

   -  **Mode**: You can select either Inline mode or Side by Side mode:

      -  **Inline mode**: Supported only for Juniper SRX firewall and BigF5
         load balancer devices. In inline mode, a firewall device is placed
         in front of a load balancing device. The firewall acts as the
         gateway for all the incoming traffic, then redirect the load
         balancing traffic to the load balancer behind it. The load
         balancer in this case will not have the direct access to the
         public network.
  
      -  **Side by Side**: In side by side mode, a firewall device is
         deployed in parallel with the load balancer device. So the traffic
         to the load balancer public IP is not routed through the firewall,
         and therefore, is exposed to the public network.

   -  **Associate Public IP**: Select this option if you want to assign
      a public IP address to the VMs deployed in the guest network. This
      option is available only if
      -  Guest network is shared.

      -  StaticNAT is enabled.

      -  Elastic IP is enabled.

      For information on Elastic IP, see `“About Elastic IP” 
      <networking2.html#about-elastic-ip>`_.

   -  **Redundant router capability**: Available only when Virtual
      Router is selected as the Source NAT provider. Select this option
      if you want to use two virtual routers in the network for
      uninterrupted connection: one operating as the master virtual
      router and the other as the backup. The master virtual router
      receives requests from and sends responses to the user’s VM. The
      backup virtual router is activated only when the master is down.
      After the failover, the backup becomes the master virtual router.
      CloudStack deploys the routers on different hosts to ensure
      reliability if one host is down.

   -  **Conserve mode**: Indicate whether to use conserve mode. In this
      mode, network resources are allocated only when the first virtual
      machine starts in the network. When conservative mode is off, the
      public IP can only be used for a single service. For example, a
      public IP used for a port forwarding rule cannot be used for
      defining other services, such as StaticNAT or load balancing. When
      the conserve mode is on, you can define more than one service on
      the same public IP.

      .. note:: 
        If StaticNAT is enabled, irrespective of the status of the 
        conserve mode, no port forwarding or load balancing rule can be 
        created for the IP. However, you can add the firewall rules by 
        using the createFirewallRule command.

   -  **Tags**: Network tag to specify which physical network to use.

   -  **Default egress policy**: Configure the default policy for
      firewall egress rules. Options are Allow and Deny. Default is
      Allow if no egress policy is specified, which indicates that all
      the egress traffic is accepted when a guest network is created
      from this offering.

      To block the egress traffic for a guest network, select Deny. In
      this case, when you configure an egress rules for an isolated
      guest network, rules are added to allow the specified traffic.

   -  **Public**: Indicate whether the network offering should be available to
      all domains or only some domains. Choose Yes to make it available to 
      all domains. Choose No to limit the scope to one or more domains.

   -  **Domain**: This is only visible When ‘Public’ is unchecked. When visible,
      this controls the domains which will be able to use this network offering. 
      A multi-selection list box will be displayed. One or more domains can be 
      selected from this list box by holding down the control key and selecting 
      the desired domains.

   -  **Zone**: This controls which zones a network offering is available in. 
      ‘All zones’ or only specific zones can be selected. One or more zones can be 
      selected from this list box by holding down the control key and selecting 
      the desired zones.

#. Click Add.

.. |L2-networks-gui.JPG| image:: /_static/images/L2-networks-gui.JPG
   :alt: Creating L2 network from GUI