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IPV6 & ADDRESS TRANSLATION ENGINEERING

IPv6 & NAT Planning Calculator

Plan IPv6 hierarchy and canonical addresses, NAT44 port capacity, deterministic CGNAT blocks and logging, plus NAT64/DNS64 synthesis.

IPv6 prefix planningNAT44/PAT capacityCGNAT port blocksNAT64/DNS64
v6

IPv6 Prefix Planner · Inputs

Supports compression/expansion, parent-child prefixes, adjacent subnets and up to 32 preview rows.

All defaults are editable engineering presets, not universal standards or vendor capacity guarantees.
/
/
R

IPv6 Prefix Planner · Planning results

Canonical address—
—
Compressed address—
Address type—
Parent network—
Prefix allocation—
Available child prefixes—
Addresses per child—
Containing child prefix—
Containing index—
Previous child—
Next child—
IndexSubnet CIDR

METHODOLOGY

Methodology and standards boundary

IPv6 prefix arithmetic

IPv6 addresses are processed as 128-bit integers. Host bits are cleared by the prefix mask; child-prefix count is 2^(new prefix − parent prefix).

NAT44 capacity

Mapping capacity is estimated from the allocatable port range, reserve, pool utilization and enabled protocol namespaces, then compared with subscriber peak demand including margin.

Deterministic CGNAT

Deterministic subscriber capacity per public IPv4 equals usable ports divided by block size; TCP and UDP normally use the same numeric block independently.

NAT64/DNS64

RFC 6052 embeds IPv4 bits after the selected prefix and reserves the u octet at bits 64–71 when the prefix is shorter than /96.

RFC: 4291 · 5952 · 6177 · 6598 · 6888 · 6052 · 6147 · 8215

FAQ

Frequently asked questions

Why are IPv6 subnet address counts so large?

IPv6 has 128 bits. A /64 leaves 64 interface-identifier bits, so it contains 2^64 addresses. The tool shows both exponent and exact integer.

Why is the port range editable?

Platforms may reserve management ports, static mappings or use different pool policies, so 1024–65535 is only a common engineering starting point.

Can TCP and UDP capacity be added?

Their port namespaces are independent and can be estimated separately, but real capacity is also limited by session tables, memory, CPU, timeouts and applications.

Is a smaller deterministic block always better?

Smaller blocks improve public-IPv4 sharing but increase port-exhaustion and application risks; choose them from busy-hour session distributions.

Can the NAT64 well-known prefix represent private IPv4?

RFC 6052 restricts the well-known prefix from representing non-global IPv4. Domain-local deployments can assess a network-specific prefix or the RFC 8215 local-use prefix.

PROJECT RECORDS

Planning history

ENGINEERING WORKFLOW

Continue the engineering workflow

Current workflowEnterprise LAN & IP Planning Workflow

Plan addressing, VLAN capacity, packet size, uplinks, optics, access policy and DNS behavior as one LAN design sequence.

Step 2 of 9
PreviousIP Subnet CalculatorCalculate IPv4, IPv6, CIDR, masks, broadcast ranges and host capacity, with VLSM planning.NextVLAN & IP Subnet Capacity PlannerPlan VLAN count, IPv4 prefix, address capacity and growth headroom.

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Engineering boundary