Path Selection

Path Selection is a core feature of the Wanscale Platform, enabling granular control over how traffic moves across your network. By defining WAN Interface Groups and applying Path Selection Policies, you can determine exactly which physical links should be used based on traffic type, link health, or cost.

1. Define WAN Interface Groups

WAN Interface Groups allow you to categorize physical links (e.g., Fiber, 5G, Starlink) and set specific health thresholds for each.

Create an Interface Group

1. Navigate to the Services page and select your VNET.
2. In the left sidebar, expand SD-WAN and select WAN Interface Groups.
3. Click the Add WAN interface group button.
4. Complete the following fields in the form:
5. Interface Group Name: Enter a short, explanatory name (e.g., Fiber, Primary, or 5G).
   • Polling Profile: Select the rate for monitoring packets. Choose a profile consistent with your WAN type.
   • Existing Interfaces: Optionally assign existing WAN interfaces to this group.
6. Specify your custom Conditions and Thresholds that define the health of links in this group. This allows you to set stricter thresholds for Fiber than for Mobile links.
7. Click Save.

* **Up:** Packet loss < 5% for ≥ 5 seconds.
* **Degraded:** Packet loss > 20% for 60 seconds OR Latency > 150ms for 10 seconds.
* **Down:** Packet loss > 70% for 3 seconds OR Latency > 250ms for 30 seconds.

2. Configure Path Selection Policies

Policies consist of rules that are parsed from top to bottom. The first rule that matches the traffic criteria will be executed.

Add a Path Selection Rule

1. Navigate to the Services page and select your VNET.
2. In the left sidebar, expand Policies and select Path Selection.
3. Click Add path (top-left) or click Add within a specific policy group.
4. Define the rule parameters in the right sidebar:
5. Name: A unique identifier for the rule.
   • Group Name (optional): The policy group for this rule. If left empty, it will be placed in the Default Policy.
   • Enable Toggle (optional): Toggle to Enable to activate the rule.
   • Policy Traffic (optional): Specify the Source and/or Destination. Leave blank for ANY. Choose from Address book, Traffic identifier or Configuration. You can add multiple entries.
   • Check Working with objects on how these are defined.
   • Match Criteria (optional): Define the conditions (e.g., link status) required for the rule to trigger. You can add multiple entries.
   • Select a WAN Interface Group, select a Condition and select the Status.
   • Function: Choose the action to take (e.g., Choose Path, then select the Path).

3. Configuration Examples

Example 1: Simple Failover

This scenario ensures traffic uses high-speed Fiber by default and switches to Starlink only if the Fiber link is unavailable.

Rule 1 (Backup):

• Name: Use Starlink when Fiber is Not Up
• Match Criteria: Fiber Internet -> Not Up
• Action: Choose Path -> Satellite Internet

Rule 2 (Default):

• Name: Use Fiber by Default
• Match Criteria: (Leave Empty)
• Action: Choose Path -> Fiber Internet

![](../assets/images/deep-dive/path-selection/simple-example-03.png)

Use the arrows in front of the rule to re-oder them

![](../assets/images/deep-dive/path-selection/simple-example-04.png)

Example 2: Application-Specific Routing (Printer Traffic)

In this scenario, we offload printer traffic to a secondary link to preserve bandwidth on the primary Fiber link.

A. Identify Traffic (Traffic Identification)

1. Click Admin in the top menu and select Traffic Identification in the left sidebar.
2. Click Add traffic identification.
3. Provide a Name and Description.
4. In the IP Subnet section, click Add and enter your printer network prefix.
5. Click Save. (Repeat this for the destination/DC prefix if necessary).

B. Create the Path Selection Rule

1. Return to the Path Selection screen for your VNET.
2. Add a new rule with the following:
3. Name: Use Starlink for Printer Traffic
   • Source: Select your server Traffic Identifier (TI).
   • Destination: Select your printer TI.
   • Action: Choose Path -> Satellite Internet.
4. Ensure this rule is moved to the top of the list so it is evaluated before general traffic rules.

Finalizing Your Setup

1. Click Save in the top-left corner of the screen.