Azure Virtual Network Routing Appliance (VNRA) is a new managed, Azure-native network routing device currently in public preview. Unlike traditional hub-and-spoke architectures that rely on VM-based network virtual appliances, VNRA runs on specialized networking hardware, acting as a high-performance forwarding layer for virtual networks.

Key benefits

  • High throughput & low latency - eliminates forwarding bottlenecks common in hub-spoke topologies
  • Horizontal scaling - scales routing capacity up to 200 Gbps configurable bandwidth
  • East-west traffic acceleration - optimized for traffic flows between spokes
  • Availability zone resilience - built-in high availability by default, no load balancer required
  • Azure-native management - managed as a top-level Azure resource via familiar tools (RBAC, governance)

How it works

VNRA is deployed in a dedicated subnet named VirtualNetworkApplianceSubnet within a virtual network. It acts as the forwarding layer for routed traffic, replacing the need for VM-based NVAs and their associated load balancers. This approach removes the performance ceiling imposed by VM SKUs and simplifies the network architecture.

Context: NVAs in Azure networking

To understand where VNRA fits, it helps to look at how NVAs are used today. A practical example is described in the article Azure VMware Solution with vWAN Routing Intent and Palo Alto Cloud NGFW, which demonstrates a hub-and-spoke architecture where a Virtual WAN hub with Palo Alto Cloud NGFW acts as a central inspection and routing point.

In that architecture:

  • The vWAN hub advertises default RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) to all connected networks
  • All inter-network traffic is forced through the hub’s security appliance for inspection
  • AVS connects via ExpressRoute with NSX-T Tier-0 learning routes via BGP/ECMP
  • Spoke VNets receive default routes plus specific learned routes from the hub

This pattern works well but introduces routing bottlenecks when traffic volume grows, especially for east-west flows between spokes. VNRA addresses exactly this problem by providing a hardware-accelerated forwarding layer that can scale horizontally without the performance limits of VM-based NVAs.

Summary

VNRA represents a shift toward hardware-accelerated, managed routing in Azure. For organizations running large hub-and-spoke topologies with heavy east-west traffic, it promises to eliminate the scaling challenges of VM-based NVAs while keeping everything Azure-native. Worth watching as it moves toward general availability.