The MPLS WG Archive

[Eric Rosen <erosen@cisco.com>]

Distributing routes is easy enough.  The  tricky part comes when you need to
decide whether  to use  a particular route.   It's especially tricky  if you
happen  to have  received two  routes to  the same  destination.   It's even
trickier if you want to make sure  that everyone's choice of a route is made
in such a way that no routing loops are formed. 

That's why when you specify a  routing procedure, you don't just specify the
messages used to distribute the  routes, you specify a decision procedure, a
set of attributes used to compare routes, etc., etc., etc. 

That in turn is why it makes  no sense to say "let's distribute routes using
LDP".   Route   distribution  doesn't   necessarily  require  BGP,   but  it
certainly requires a routing protocol, and LDP is not a routing protocol.