Method: IPAddress::IPv4#subnet

Defined in:
lib/ipaddress/ipv4.rb

#subnet(subprefix) ⇒ Object

This method implements the subnetting function similar to the one described in RFC3531.

By specifying a new prefix, the method calculates the network number for the given IPv4 object and calculates the subnets associated to the new prefix.

For example, given the following network:

ip = IPAddress "172.16.10.0/24"

we can calculate the subnets with a /26 prefix

ip.subnets(26).map{&:to_string)
  #=> ["172.16.10.0/26", "172.16.10.64/26", 
       "172.16.10.128/26", "172.16.10.192/26"]

The resulting number of subnets will of course always be a power of two.


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# File 'lib/ipaddress/ipv4.rb', line 682

def subnet(subprefix)
  unless ((@prefix.to_i)..32).include? subprefix
    raise ArgumentError, "New prefix must be between #@prefix and 32"
  end
  Array.new(2**(subprefix-@prefix.to_i)) do |i|
    self.class.parse_u32(network_u32+(i*(2**(32-subprefix))), subprefix)
  end
end