etc/iproute2/rt_dsfield

   1 0x10    lowdelay
   2 0x08    throughput
   3 0x04    reliability
   4 # This value overlap with ECT, do not use it!
   5 0x02    mincost
   6 # These values seems do not want to die, Cisco likes them by a strange reason.
   7 0x20    priority
   8 0x40    immediate
   9 0x60    flash
  10 0x80    flash-override
  11 0xa0    critical
  12 0xc0    internet
  13 0xe0    network