Every SD-WAN site can use more than one internet or private circuit at once. The edge bonds them into a single logical link and continuously measures each one, so your applications ride whichever transport is healthiest right now — the multi-transport link bonding and failover at the core of the service.
Supported transports
| Transport | Typical role |
|---|---|
| Fiber / dedicated | Primary for latency-sensitive and high-throughput traffic. |
| Broadband (cable/DSL) | Cost-effective capacity and a diverse failover path. |
| LTE / 5G | Wireless backup, or primary for sites without wired options. |
| MPLS / private | Optional, for sites still on a private WAN during migration. |
Add a transport to a site
Register the circuit
In the Network Portal, open the site and choose Transports → Add. Enter the circuit type, bandwidth, and whether it's metered (so the edge can prefer unmetered links).
Plug it into the edge
Connect the circuit to a WAN port on the SD-WAN edge. The edge auto-detects the link and begins measuring it.
Set a role
Mark each transport as primary, secondary, or backup — a starting preference the edge overrides in real time based on health.
How bonding works
The edge sends continuous probes across every transport to measure latency, loss, and jitter, and combines the links in one of two modes per traffic class:
- Active/active — traffic is spread across healthy links for more total capacity; a session can move mid-flow if a link degrades.
- Active/backup — traffic prefers the primary and fails over to a backup only when the primary breaks a threshold.
Which mode applies to which traffic is set by your application-steering and QoS policies.
Metered links & data caps
Mark LTE/5G or capped broadband as metered and set a monthly budget. The edge avoids metered links for bulk traffic and uses them for failover or real-time traffic only, so a backup circuit doesn't produce a surprise bill.
Note
Bonding needs no change at the application layer — servers and clients see one network. The edge handles measurement, path selection, and failover beneath them. See High availability for failover behavior.