# Create Link Usage Profile elements

Link Usage Profile elements define which link types are preferred, avoided, or not used for specific types of traffic.

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Also, the Link Usage Profile elements can be used to enable the packet duplication functionality for Multi-Link tunnels or Forward Erasure Correction (FEC) functionality for any IPsec tunnels.

The link usage exceptions in the Link Usage Profile element override the link selection options in QoS Class elements. If you do not specify an exception for a particular QoS class, the connection is selected according to the link selection options in the QoS Class element.

For each link type, you can add QoS Class elements to one of the following categories:

- Prefer — The specified traffic uses the link type unless a connection with significantly higher quality is available.

  For VPN connections, links that are preferred on both ends of the connection are preferred over those that are preferred on just one end of the connection.

- Avoid — The specified traffic uses link type only if necessary.
- Do Not Use — The specified traffic must not use the link.

When you select a Link Usage Profile element in the properties of an Security Engine, the settings defined in the Link Usage Profile element are applied to outbound traffic that uses outbound Multi-Link.

When you select a Link Usage Profile element in the properties of a policy-based VPN, Route-based Tunnels group, or a VPN broker domain, the settings defined in the Link Usage Profile element are applied to all tunnels in the VPN according to their link types.

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

## Steps

1. Select Secure SD-WAN.
2. Browse to Other Elements > Link Usage Profiles.
3. Right-click Link Usage Profiles, then select New Link Usage Profile.
4. Configure the settings, then click OK.

## Link Usage Profile Properties dialog box

Use this dialog box to specify exceptions to the default link selection options.

Option | Definition
--- | ---
General tab
Name | The name of the element.
Default SD-WAN Link Balancing Preference | Specifies how the traffic is balanced over the links. You can use the slider to set the link balancing preference to determine which of the following is favored more: Equal Balancing: When slider position is set to the left-most position, the traffic is initially equally distributed among the links. But Over time as the engine gathers information about the behavior of the links, the traffic balancing changes between the links. Best link: The best available link is selected to transfer traffic. The best link is determined by considering the following link selection values: Bandwidth Jitter Latency Packet drop rate Link stability Also, the slider positions moving towards Best Link determine how strongly the link selection values are considered. Note: By default, the slider is set to the left-most position (Equal Balancing). You can only specify the Default SD-WAN Link Balancing Preference option and save the element to use it. The default link balancing preference can only be set per engine. You must select this link usage profile in engine properties to enable it. For more details refer to the Engine Editor > Routing > Link Usage section in the Create Security Engines topic. The Default SD-WAN Link Balancing Preference option is not applicable for link usage profiles with Route Based VPN tunnel group, Policy Based VPN, and VPN Broker.
Link Usage Exceptions | Exceptions that override the default link selection options in QoS Class elements.
Link Type | The Link Type element for which to create an exception.
Prefer | Specifies the types of traffic that use the link unless a connection with significantly higher quality is available. You can add QoS Class elements to this cell.
Avoid | Specifies the types of traffic that use the link only if necessary. You can add QoS Class elements to this cell.
Do Not Use | Specifies the types of traffic that must not use the link. You can add QoS Class elements to this cell.
Add Link Type | Adds a row to the table. Click Add Link Type, and then select a link type to add it to the table.
Remove Link Type | Removes the selected row from the table.
Category (Optional) | Includes the element in predefined categories. Click Select to select a category.
Comment (Optional) | A comment for your own reference.
Mutli-Link Packet Duplication tab
Apply Multi-Link Packet Duplication for QoS classes | Displays the list of QoS classes that are used for packet duplication: Click Add, and then select a QoS class to add it to the list. Select a QoS class in the list, and then click Remove to remove the QoS Class from the list.
Do not duplicate on Link Types | Displays the list of link types that must not be used for packet duplication: Click Add, and then select a link type to add it to the list. Select a link type in the list, and then click Remove to remove the link type from the list.
Forward Erasure Correction tab
Apply Forward Erasure Correction for QoS classes | Displays the list of QoS classes that select traffic for FEC: Click Add, and then select a QoS class to add it to the list. Select a QoS class in the list, and then click Remove to remove the QoS Class from the list.
Packet drop threshold to start FEC | Enter the packet drop threshold value in percentage to start FEC. For example, 2% or 50%. Note: If the value 0 is entered, then FEC is always enabled.
FEC Percentage | From the drop-down list, select the percentage of the correction packets relative to the data packets from the options 10 to 50. Note: The FEC percentage affects the amount of extra correction packets that are generated and sent.
Use FEC only on Link Types | Displays the list of link types that are only used for Forward Erasure Correction: - Click Add, and then select a link type to add it to the list. Select a link type in the list, and then click Remove to remove the link type from the list. Note: If no Link Type selection is done, FEC can be used on any type of link.