Router Shaping in Azure Virtual WAN

Router shaping lets you control the bandwidth allocated to each type of traffic flowing through a Virtual WAN hub. By configuring shaping policies, you can ensure critical applications receive the required throughput while preventing less‑important traffic from consuming excess capacity.

When to Use Router Shaping

Multi‑tenant environments where each tenant must be guaranteed a minimum bandwidth.
Scenarios with a mix of latency‑sensitive (e.g., VoIP) and bulk transfer (e.g., backup) traffic.
Compliance requirements that mandate bandwidth caps for specific services.

Key Concepts

Term	Description
Shaping Policy	A collection of rules that define bandwidth limits per traffic class.
Traffic Class	A grouping based on protocol, port, or custom tags (e.g., “Video”, “Backup”).
Maximum Bandwidth (Mbps)	Upper limit for a traffic class on a specific hub.
Guaranteed Bandwidth (Mbps)	Minimum reserved bandwidth; traffic will be prioritized up to this value.

Creating a Shaping Policy

Navigate to Virtual WAN > Hubs in the Azure portal.
Select the hub you want to configure.
Click Router Settings > Shaping Policies.
Press Create Policy and fill in the following fields:
- Name: Descriptive identifier (e.g., Video_Streaming_Policy).
- Traffic Class: Choose from predefined or create a custom class.
- Maximum Bandwidth: Enter the ceiling value.
- Guaranteed Bandwidth: Enter the floor value.
Save the policy. The hub will apply the shaping rules within a few minutes.

Example: Prioritizing VoIP Traffic


{
  "policyName": "VoIP_Priority",
  "trafficClass": "VoIP",
  "maxBandwidthMbps": 500,
  "guaranteedBandwidthMbps": 200
}

This policy guarantees 200 Mbps for VoIP traffic and caps it at 500 Mbps, ensuring consistent call quality even during peak usage.

Monitoring & Diagnostics

Use the Metrics Explorer to view real‑time bandwidth consumption per traffic class. The RouterShapingPolicy log provides audit information whenever a policy is added, modified, or deleted.

Best Practices

Start with conservative guarantees and adjust based on observed traffic patterns.
Combine shaping with Azure Firewall policies for layered security.
Regularly review metrics to avoid over‑provisioning.