Cisco Catalyst SD-WAN Onboarding Guide, Releases 26.x and Later

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Cisco Catalyst SD-WAN Onboarding Guide, Releases 26.x and Later

Configure the port offset

Updated: July 7, 2026

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Configure a port offset when multiple Cisco vEdge devices are behind the same full-cone NAT device to avoid port conflicts.

The purpose of configuring a port offset is to avoid port conflicts when multiple Cisco vEdge devices are deployed behind the same full-cone NAT device.

When two or more Cisco vEdge devices are behind the same full-cone NAT device, one device can use the default port offset, and you should configure a port offset on the remaining devices. The port offset can be a value from 0 through 19. The default port offset is 0.

Figure 1. Example of port offset configuration
Example of port offset configuration, where default port offset of 0 is set at vEdge-1 and 1 is set at vEdge-2.

Procedure

Configure the port offset on the device.

Example:

Device(config)# system port-offset number

The port offset is configured. In the example where vEdge-1 uses the default port offset of 0 and vEdge-2 has a port offset of 1:

  • vEdge-1 attempts to connect first using base port 12346. If that attempt is not successful, the router attempts port 12366, 12386, 12406 and 12426.

  • vEdge-2 has a port offset of 1, so the first port it attempts to connect on is 12347 (12346 plus offset of 1). If it fails to connect using port 12347, the router hops by increments of 20 and attempts to connect on ports 12367, 12387, 12407, and 12427.