# Create Server Pool elements

The Server Pool element collects servers that provide a particular service into a single element and defines the settings for handling the inbound traffic.

## Before you begin

You must have a Host element that represents the internal IP address of each server that you want to add to the Server Pool.

##

Note: Make sure that other NAT configurations do not overlap with the internal and external IP addresses of the Server Pool.

We recommend creating a separate Server Pool element for each type of service. Add servers to Server Pools based on the services that the servers provide.

The Server Pool can have up to 255 members. If you have only one server and you want to balance the inbound traffic between your NetLinks, you can define a Server Pool element with just one host. This approach allows dynamic DNS update information to be used to prevent contacting clients from attempting to use a NetLink that is out of service.

For more details about the product and how to configure features, click Help or press F1.

## Steps

1. Select Configuration, then browse to SD-WAN.
2. Browse to Traffic Handlers.
3. Right-click Traffic Handlers, then select New > Server Pool.
4. In the Name field, enter a unique name for the Server Pool.
5. Define the external IP addresses of the Server Pool.
   1. In the External Addresses section, click Add.
   2. Select a NetLink element.
      Tip: To load-balance servers without using Multi-Link for inbound traffic management, select Not Specified.
   3. From the Network drop-down list, select the network to which the Server Pool’s external IP address belongs.
   4. In the IP Address field, enter the external IP address for the Server Pool.
      Note: The IP address you enter here must be reserved for NAT and it must not be used by any equipment in your network. Remember to update your DNS server with any changes in IP addressing.
   5. From the Status drop-down list, select Enabled.
6. Add servers to the list of Server Pool members.
   1. In the Server Pool Members section, click Add.
   2. Add the Host elements that represent the internal IP address of the servers to the list of Server Pool members.
      Tip: For servers that have some special role in the SMC configuration, you can add the existing Server element.
   3. From the Allocate Traffic to Servers by drop-down list, select the granularity for the server selection.

      Consider the type of traffic when selecting the allocation method. Connections from the same source might be directed to different servers in the following cases:

      - Using the Host setting if the host’s IP address apparent to the SMC can change.
      - Using the Connection setting in all cases.

      Depending on the services offered, directing connections from the same source to different servers might reduce the quality of service.

7. Click OK.

## Server Pool Properties dialog box

Use this dialog box to define Server Pools.

Option | Definition
--- | ---
General tab
Name | The name of the element.
Category (Optional) | Includes the element in predefined categories. Click Select to select a category.
Comment (Optional) | A comment for your own reference.

Option | Definition
--- | ---
External Addresses section
NetLink | Specifies the NetLink you want to use.
IP Address | Specifies the external destination IP address for the Server Pool.
Status | Shows the NetLink status: Enabled or Disabled. Enabled NetLinks are used in the Server Pool.
Proxy ARP/Neighbor Discovery | When enabled, automatically generates a proxy ARP or neighbor discovery entry for the external IP address in the selected network.
Add | Opens the External Address dialog box.
Edit | Opens the External Address dialog box and allows you to change the settings for the selected NetLink.
Remove | Removes the selected external address.
Enable Dynamic DNS Updates | Enables Dynamic DNS Updates from the Server Pool to the DNS Server.
DNS Server | Specifies the External DNS Server element to which the DDNS updates are sent. Note: Only IPv4 addresses are supported for DNS servers for DDNS updates. The External DNS Server element must have an IPv4 address.
FQDN | Specifies the fully qualified domain name (FQDN) for the Server Pool service (for example, “www.example.com”).

Option | Definition
--- | ---
Server Pool Members section
Element | Shows the names of the elements selected as pool members.
IP Address | Shows the IP addresses of the elements selected as pool members.
Add | Adds a row to the table.
Remove | Removes the selected row.
Up | Moves the selected row up.
Down | Moves the selected row down.
Allocate Traffic to Servers by | Defines how likely it is that traffic is redirected to a particular server. Usually it is best to select the least granular option that still produces an acceptable distribution of traffic. The options are (from least granular to most granular): Not Defined — Not Defined has the same effect as the Source Network option. Source Network — Directs traffic coming from the same C-class network to the same server. This option is a good choice when connections come from many different networks. Host — Directs traffic coming from the same IP address to the same server. This option is a good choice when a large portion of connections come from different hosts in the same C-class network. Connection — Makes a new traffic management decision for each new connection. This choice might be necessary if a large portion of connections uses just one IP address. Order — Allocates traffic based on the order of the elements on the list.

Option | Definition
--- | ---
Monitoring tab
Frequency Check | Specifies how often you want the availability to be checked.
Method | Specifies the method for monitoring the availability of the servers in the Server Pool. Ping — Uses ICMP echo request (ping) messages to monitor the availability of the servers. Agent — Uses the Server Pool Monitoring Agent feature. Before enabling this method, make sure that you have installed and configured the Monitoring Agents on all servers. TCP — Checks that a specific TCP service is available. HTTP — Checks that the HTTP service is available.

Option | Definition
--- | ---
When Method is Agent
Port | Defines the port number.

Option | Definition
--- | ---
When Method is TCP
Port | Defines the port number.
Request (Optional) | Specifies the string of ASCII text that the firewall sends.
Response (Optional) | Specifies the string of ASCII text that you expect to receive.

Option | Definition
--- | ---
When Method is HTTP
Port | Defines the port number.
Path | Specifies the path to the webpage.
Host Header (Optional) | Specifies the host name of the web server.
Response (Optional) | Specifies the string of ASCII text that you expect to receive.

## External Address dialog box

Use this dialog box to define the external address of a Server Pool as a property of the Server Pool element.

Option | Definition
--- | ---
NetLink | Specifies the NetLink you want to use.
Network | Specifies the network to which the Server Pool’s external IP address belongs.
IP address | Specifies the external IP address for the Server Pool.
Status | Specifies the NetLink status. Enabled — The NetLink is used in the Server Pool. Disabled — The NetLink is not used in the Server Pool.
Automatic Proxy ARP / Neighbor Discovery Entry Generation | When enabled, automatically generates a proxy ARP or neighbor discovery entry for the IP address in the selected network. If you do not select this option, you must define the ARP or neighbor discovery entry manually in the Firewall element properties.