client.rb

#!/usr/bin/ruby

require "socket"
require 'timeout'

udps = []
5.times do 
udps << UDPSocket.open()
end

addrs = []
5.times do
  addrs << Socket.pack_sockaddr_in(10000, "NLB Endpoint") #編集
end

while true do 
  5.times do |i|
    begin
      Timeout.timeout(3) do
        udps[i].send("HELLO", 0, addrs[i])
        print "#{udps[i].recv(65535)} "
      end
    rescue Timeout::Error
      print '(timeout)          '
    end
  end
  puts ""
  sleep 3
end

server.rb

#!/usr/bin/ruby

require "socket"
host = Socket.gethostname
Socket.udp_server_loop(10000) do |data, src|
  src.reply host
end