A discuss from Lars Eggert:

   DISCUSS: "Node cannot saturate the network" is a very weak statement
   when it comes to congestion control, because it does not take
   concurrent traffic into account. Furthermore, bandwidth limits of, for
   example, "5% of the node's lowest-speed interface" also don't have the
   desired effect. Consider a router with only Gigabit Ethernet
   interfaces. By the definition above, it'd be allowed to send at a rate
   of 50Mb/s. If one of those links connects to a layer-2  switch that
   connects to the next router using 10Mb/s Ethernet, those 50Mb/s will
   overload the link. A similar case exists when a non-NSIS router is
   located between two NSIS routers. Even worse, fixed rate limits do not
   take concurrent network traffic along the link/path into account.
   Along a fully loaded link/path, adding 5% traffic can significantly
   impact concurrent flows. What an appropriate mechanism could be
   deserves some more discussion. There are several options, such as
   limiting each MA to a single outstanding D-mode request, which limits
   the additional traffic to be proportional to the number of MAs/flows,
   or more complex schemes if that is too limiting (AIMD, etc.)