What is a Path?

A path is the end-to-end route that carries traffic between a local branch and a remote branch in an SD-WAN network, formed by pairing a local WAN circuit with a remote WAN circuit. When either branch has more than one circuit, multiple candidate paths exist between the same two sites.

Key takeaways

• A path pairs one local WAN circuit with one remote WAN circuit.
• Multiple circuits per branch create multiple candidate paths.
• Path priority and SLA compliance decide which path carries a flow.
• SLA Monitoring probes every path, per forwarding class, to track health.
• Continuous evaluation can shift real-time flows to a better path.

On this page: Why it matters · How it works · Types · Paths & Versa · FAQ

Why are paths important?

SD-WAN’s central promise is using every available WAN link intelligently instead of routing statically over one connection. That only works if the network can evaluate performance at the level of a specific route, not just a circuit. A branch’s Internet-1 circuit can look healthy overall while the particular path it forms to one remote branch is congested, because the problem lives on the remote circuit or somewhere in between. Tracking paths individually lets SD-WAN detect that asymmetry.

Path awareness also makes automated failover and load balancing possible. Each path is monitored against configured latency, jitter, and packet-loss thresholds, so the network knows which paths meet a session’s requirements and which have degraded. New flows go to the highest-priority compliant path; real-time flows can be moved off a path that stops complying – otherwise a device could react only to a circuit going fully down, not a route degrading.

What is a path?

In Versa SD-WAN terminology, a circuit and a path are related but distinct. A circuit is a WAN endpoint on a single VOS device – an Ethernet, DSL, or LTE interface such as Internet-1 or Internet-2. A path is the end-to-end route formed by pairing a local circuit with a remote circuit. If Branch-1 and Branch-2 each have two circuits, four paths exist between them, one per combination – and the same model extends to paths a branch forms toward its controllers.

Versa branches continuously monitor every path independently. SLA Monitoring sends request-response probes down each path at a configured interval, per forwarding class, computing delay, jitter, and loss in both directions. That per-path visibility is what a forwarding profile consults when it assigns priority, marks a non-compliant path SLA-violated, and picks the next candidate path.

Types of paths

Paths vary along two axes: how they’re prioritized and what topology they traverse.

By priority, a forwarding profile ranks candidate paths and treats the highest-priority SLA-compliant path as primary. A path can also be marked last resort, used only when every higher-priority path is down – a common way to keep a metered LTE path in standby.

By topology, a spoke-to-spoke-direct design gives two branches a path that runs straight between them. A spoke-to-spoke-via-hub design instead routes the data path through a hub site; a second hub gives each spoke pair a redundant path. The same branch pair can have direct and hub-relayed paths available at once, with priority and SLA compliance deciding which carries traffic.

Paths & Versa

Versa’s forwarding profiles turn path awareness into a steering decision. Administrators set circuit priority, an SLA profile’s latency, jitter, and loss thresholds, and a load-balancing method, and the SD-WAN traffic-steering engine ranks every path toward a remote branch before choosing where to send a flow. Continuous evaluation can move an existing real-time flow to a better path as conditions change.

SD-WAN Path Policies drive SLA Monitoring: every branch probes each path toward peer branches and controllers, per forwarding class, to keep delay, jitter, and loss figures current. Branches also fold in metrics distributed over BGP to pick the best path to a SaaS application. The Versa SD-WAN Design Guide covers how topology choices, such as routing through a hub versus directly between spokes, shape which paths exist in a deployment.

Frequently asked questions

What is the difference between a path and a circuit?

A circuit is a single WAN endpoint on one device, such as a branch’s Internet-1 interface. A path is the end-to-end route formed by pairing a local circuit with a remote circuit – so one circuit can be part of several different paths, one for each remote circuit it pairs with.

How does Versa SD-WAN decide which path to use for a new flow?

The forwarding profile ranks paths by priority and checks each against its SLA profile’s thresholds. New flows go to the highest-priority SLA-compliant path; if multiple compliant paths share the top priority, traffic is load-balanced across them, typically using weighted round-robin.

What happens when a path stops meeting its SLA?

The path is marked SLA-violated, a priority level just below the lowest configurable value. Path-selection logic then looks for another compliant path with a higher priority. Existing flows only move onto it immediately if continuous evaluation has been enabled for that particular traffic type.

Can a network have more than one path between the same two branches?

Yes. Each WAN circuit at one branch can pair with each circuit at the other, so two circuits per branch produce four possible paths. Topology multiplies the count: a spoke pair can have a direct path plus a redundant path per configured hub.

Does Versa monitor paths to controllers as well as to other branches?

Yes. SD-WAN Path Policies apply SLA Monitoring to paths toward both peer branches and controllers, with different default probe intervals – roughly every 2 seconds toward branches using the expedited-forwarding class, and every 10 seconds toward controllers using the network-control class.

More on paths

If you want to learn more, these are sources we trust.

Related terms

If you’re reading about paths, these are worth looking at next.