The Prefix Delegation (PD) model is a variant of the Routed prefix architecture in which the Wi-SUN Border Router obtains its IPv6 prefix dynamically from an upstream delegating router using DHCPv6-PD (Prefix Delegation). The Border Router then advertises and subdivides this prefix within the Wi-SUN mesh, ensuring that all nodes receive globally routable addresses consistent with the upstream network’s addressing plan.

This approach centralizes address management and aligns Wi-SUN networks with standard enterprise or service-provider IPv6 practices.

When to use

Choose Prefix delegation if:

  • The deployment must integrate directly into an existing IPv6-enabled core network.

  • Address space needs to be centrally allocated and coordinated across multiple Border Routers or segments.

  • Upstream routers (service provider, aggregation or any DHCPv6 server or delegator) already support DHCPv6-PD and maintain prefix lease policies.

This model is especially suitable for operators who want Wi-SUN networks to behave like other IPv6 access technologies managed by their core routing infrastructure.

Pros and cons

  • Pros

    • Seamless integration with existing IPv6 prefix plans and upstream routing.

    • Automates prefix allocation and reduces manual configuration.

    • Supports hierarchical scaling across multiple Border Routers.

    • Keeps Wi-SUN addressing aligned with enterprise or ISP policies.

  • Cons

    • Depends on the availability of an upstream DHCPv6-PD delegator.

    • Prefix leases are temporary — failures to renew can affect connectivity.

    • Requires coordination between Wi-SUN and core network teams for prefix planning.

    • Slightly more complex to troubleshoot than a static configuration.

Considerations

Prefix delegation brings these operational considerations:

  • Prefix partitioning: Delegated prefixes must be distributed consistently across routers and meshes to avoid overlap.

  • Lease management: Delegated prefixes are typically temporary and assigned dynamically. Prefix assignment policies must be carefully designed to limit or eliminate the need for address reassignment within the Wi-SUN network.

  • Monitoring and planning: Continuous monitoring of delegated prefixes and renewal timing helps ensure smooth operation in long-running deployments.