An IPv6 broadband deployment has two separate addressing jobs. The customer router needs connectivity on its WAN, and it needs a prefix it can use on networks behind it. A WAN address alone does not give the household or business a routed LAN. A delegated prefix alone does not describe how the WAN discovers its next hop.
Keep those jobs separate in the address plan, provisioning policy and acceptance tests. Netavo models them as different pool families: ipv6-wan supplies a /64 per subscriber, while ipv6-pd supplies a delegated prefix whose size is set by delegationLength. IPv4 and IPv6 belong to one subscriber session.
The two allocations
The WAN /64 belongs to the subscriber's access link. It provides the prefix from which the customer router can obtain its global WAN address. Do not confuse allocating that /64 with handing the CPE a /64 to distribute across its internal networks.
The delegated prefix is routed towards the subscriber. The CPE can divide it into /64 LAN prefixes for its internal interfaces. With a /56 delegation, for example, there are 256 possible /64 subnets. That is address-plan arithmetic, not a requirement that a customer use every subnet.
| Allocation | Netavo pool family | Purpose |
|---|---|---|
| IPv4 address | ipv4 |
IPv4 service on the subscriber session |
| IPv6 WAN /64 | ipv6-wan |
Addressing on the access link |
| Routed IPv6 prefix | ipv6-pd |
Networks behind the subscriber router |
Choose delegation sizes according to the service you intend to offer. Larger delegations leave customers room for multiple networks; smaller delegations fit more subscribers into an aggregate. Keep enough space for growth, and document how static assignments and pool assignments coexist.
RA, SLAAC and DHCPv6-PD have different jobs
Router Advertisements communicate IPv6 router and prefix information on a link. SLAAC lets a host form an address from an advertised prefix when the advertisement permits autonomous configuration. DHCPv6 prefix delegation uses an IA_PD exchange to give a router a prefix for downstream networks.
The often-asked question, “SLAAC vs DHCPv6-PD?”, therefore combines two different decisions. SLAAC can address the WAN while DHCPv6-PD supplies the LAN prefix. They can operate together. DHCPv6 address assignment through IA_NA is another WAN mechanism; it is distinct from IA_PD.
On an Ethernet access link, check receipt of Router Advertisements and installation of the default route independently of DHCPv6 success. A CPE can receive a delegated prefix yet fail to forward traffic because it lacks a usable upstream route. Conversely, its own diagnostics may reach IPv6 destinations while every LAN client remains IPv4-only.
For each test, inspect both the router and a device behind it. Confirm that the LAN device receives an address, installs its route and exchanges traffic through the delegated prefix. A successful ping from the CPE is only a WAN test.
A real addressPools example
This is an overlay for an existing configuration. It assumes a residential VRF already exists and that subscriber policy selects these pools. The IPv6 ranges are documentation prefixes; replace them with space allocated to your network before deployment.
{
"addressPools": [
{
"name": "residential-v6-wan",
"family": "ipv6-wan",
"vrf": "residential",
"subnets": [
{ "prefix": "2001:db8:1000::/48", "announce": true }
]
},
{
"name": "residential-v6-pd",
"family": "ipv6-pd",
"vrf": "residential",
"delegationLength": 56,
"subnets": [
{ "prefix": "2001:db8:2000::/40", "announce": true }
]
}
]
}
The WAN pool allocates /64s. The PD pool allocates /56s because delegationLength is 56. The two aggregates are separate, making ownership and route inspection easier to reason about. Their presence in the file does not by itself grant IPv6 service to every subscriber.
For RADIUS-driven selection, Framed-IPv6-Pool identifies the WAN pool and Delegated-IPv6-Prefix-Pool identifies the delegation pool. Check the returned pool names against the configuration and the session's VRF. Also verify upstream routing through FRR: allocation succeeds locally only to be useful when return traffic can reach that subscriber.
Pool ownership is local to an appliance. Do not configure overlapping allocation ranges on parallel BNGs and assume they share a lease database. Address continuity across a migration needs an explicit allocation plan.
IPoE: bring up IPv6 with the subscriber
In Netavo's IPoE path, DHCPv4 creates the subscriber session. For a subscriber entitled to IPv6, WAN allocation can happen during that initial bring-up instead of waiting for DHCPv6. The ipoe.ipv6WanSlaac and ipoe.unsolicitedRa settings default to enabled.
The allocated WAN /64 is advertised with autonomous and on-link flags. If the CPE also requests an IA_NA address, Netavo uses ::1 within that same subscriber /64 rather than allocating another WAN block. Prefix delegation remains a separate DHCPv6 operation.
This distinction matters when troubleshooting. First establish that the authenticated session has IPv6 entitlement and a WAN allocation. Then inspect RA delivery and the CPE's WAN configuration. Finally inspect the IA_PD exchange and the route towards the delegated LAN prefix. Treating all three as “DHCPv6 failed” hides where the exchange stopped.
An existing session that predates the relevant allocation can acquire the IPv6 configuration at a subsequent DHCPv4 renewal. Include renewal behaviour in rollout testing, rather than checking only freshly connected clients.
PPPoE: addressing sits above IPv6CP
On a PPP link, IPv6CP brings up IPv6 on the link itself, negotiating the interface identifiers and the link-local addresses at each end. By design it goes no further. IPv6CP does not carry a global address or delegate a prefix; that is DHCPv6's job, and on PPP the DHCPv6 exchange runs over the link once IPv6CP is open.
So the delegated prefix reaches a PPPoE subscriber the same way it reaches an IPoE one. After IPv6CP, the CPE runs DHCPv6 over the PPP link and receives its delegated prefix (IA_PD), along with its WAN address by DHCPv6 (IA_NA) or from the router advertisement, all from the same ipv6-wan and ipv6-pd pools. A subscriber gets a routed IPv6 LAN over PPPoE exactly as it does over IPoE. Only the link bring-up differs.
The practical point for testing is that IPv6CP reaching its open state tells you the link is up, not that an address or prefix has been assigned. Verify the DHCPv6 exchange over the link, the IA_NA address and the IA_PD prefix, before you call a PPPoE line's IPv6 complete.
Dual-stack is one session
Netavo's session model ties IPv4 and IPv6 to the same access circuit. That gives operations one subscriber context for service state and accounting correlation. It also means tests should consider what happens when only one address family fails.
Exercise IPv4 and IPv6 together, then inspect each independently. Confirm rate enforcement, routing isolation and service restrictions on both families. A suspension policy that blocks IPv4 while IPv6 remains reachable does not implement the intended service state.
Test the CPEs you actually deploy
CPE behaviour varies across models and firmware. Test initial connection, renewal, reboot, loss of the WAN link and replacement of the delegated prefix. Check that LAN clients stop using an old prefix appropriately and that the router requests delegation after reconnecting.
Include DNS and path-MTU behaviour in end-to-end tests. Use a wired LAN client as well as router diagnostics, and retain the relevant RA and DHCPv6 exchanges with the model and firmware version.
Qualify several representative CPE models before a broad rollout. One router accepting a WAN address and prefix does not establish compatibility with the rest of the installed estate.
Use the free evaluation, the full production build licensed for up to 50 concurrent subscribers, for the CPE matrix. Consult the manual for pool configuration and current protocol support.