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NetSimLab Docs

Subnet calculator

The Subnet calculator helps you plan addressing for infrastructure networks and lab VLANs. It works entirely in your browser and doesn’t change any data.

IPv4

Section titled “IPv4”

  1. Type a network in CIDR form in the IPv4 box, e.g. 10.10.0.0/22.

  2. Read the results:

    • Network, Netmask, Wildcard (for ACLs and OSPF) and Broadcast.
    • Host range and Addresses (total and usable).
    • Class / type: the address class, and whether it’s private (RFC 1918 / CGNAT) or public.

    If you typed an address with host bits set (e.g. 10.10.1.5/22), it tells you the real network address.

  3. To carve it up, set Split into / to a longer prefix, e.g. /24. Every resulting subnet is listed (the first 256 if there are more).

IPv6

Section titled “IPv6”
  1. Type a prefix in the IPv6 box, e.g. 2001:db8:100::/48.
  2. Read the Prefix, the Expanded form, the First and Last address, the number of Addresses, how many /64 subnets it holds, and its Scope (global unicast, unique local, link-local…).
  3. Set Split into / (e.g. /64) to list the subnets.