IPv6 CIDR parse

ipv6-cidr-parse · version 1.0.0 · URLs & IP addresses · free, no key needed

Parse an IPv6 CIDR block into its canonical network address, prefix, first/last address, and total address count.

Use when you need to: ipv6 cidr parse · ipv6 subnet info · ipv6 cidr to network details.

Supported

• ipv6 cidr parse
• ipv6 subnet info
• ipv6 cidr to network details

Not supported

• IPv4
• host-address CIDR notation (host bits must be zero)
• subnet-router anycast/usable-host distinctions

Behavior

• cidr is address/prefix (address in any RFC 4291 textual form) with prefix a canonical decimal integer 0-128 and no leading zeros except 0.
• The network address must have host bits zero; otherwise the tool throws "cidr host bits must be zero".
• network, first_address and last_address are RFC 5952 canonical strings; network equals first_address.
• total_count is the canonical decimal string 2^(128-prefix), the number of addresses in the block. IPv6 has no broadcast address and this tool draws no usable/reserved distinction.

Input

• cidr (string, required): max length 49

Output

• network (string, required): max length 45
• prefix (integer, required): min 0; max 128
• first_address (string, required): max length 45
• last_address (string, required): max length 45
• total_count (string, required): max length 39; pattern ^(0|[1-9][0-9]*)$

Limits

• max cidr length: 49
• prefix min: 0
• prefix max: 128

Example

Request input:

{
  "cidr": "2001:db8::/32"
}

Response:

{
  "result": {
    "network": "2001:db8::",
    "prefix": 32,
    "first_address": "2001:db8::",
    "last_address": "2001:db8:ffff:ffff:ffff:ffff:ffff:ffff",
    "total_count": "79228162514264337593543950336"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "ipv6-cidr-parse",
  "version": "1.0.0",
  "input": {
    "cidr": "2001:db8::/32"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/ipv6-cidr-parse/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"cidr":"2001:db8::/32"}'

The machine-readable contract is at /v1/tools/ipv6-cidr-parse/versions/1.0.0.

CLI

node cli.mjs run ipv6-cidr-parse 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• IPv4 CIDR parse: Parse an IPv4 CIDR block into its network, broadcast, netmask, wildcard mask, usable host range and address counts.
• IPv6 CIDR contains: Test whether one IPv6 CIDR block fully contains another IPv6 CIDR block.
• IPv6 CIDR overlap: Test whether two IPv6 CIDR blocks overlap (share at least one address).
• IPv6 in CIDR: Test whether an IPv6 address lies in a CIDR prefix whose host bits are zero.
• IPv6 parse: Parse an IPv6 address (any RFC 4291 textual form) into its 8 hextets and a 128-bit integer string.
• IPv6 range to cidrs: Convert an arbitrary IPv6 address range into the minimal list of CIDR blocks that exactly covers it.