#! /usr/local/bin/ruby

vlan = "20,1500-1503,50,30-35,5-8,300-302"
str = vlan.gsub(/-/, "..").
        split(/,/).
        flat_map {|s| 
          x = eval(s)
          x.is_a?(Range) ? x.to_a : x
        }.sort!.join(",")
p str