[Babel-users] Stub-only Babel revisited

[Juliusz Chroboczek]

>> You might remember the stub-only implementation of Babel that I published
>> last week-end:

> I'm still not sure what is meant in general by a "stub-only"
> implementation.

It's one of those "well-known concepts" that everyone defines slightly
differently.  I've seen the following definitions:

  (1) a stub network is a network that is attached to the Internet at
      a single point (has a single border router);
  (2) a stub network is a non-transit network whose border routers only
      announce the default route into the network;
  (3) as (2), but composed of a single link.

Everyone agrees that this is a stub network (you've probably got one of
those at home):

    Internet ---- R --- client LAN

(1) and (2) but not (3):

                     A --- client LAN
                    /|
                   / |
    Internet ---- R  |
                   \ |
                    \|
                     B --- client LAN

(2) and (3) but not (1):


    Internet ---- R 
                  |
                  | client LAN
                  |
    Internet ---- R'


(2) is like the above, but replace the single link between R and R' by
a multi-hop topology that is reasonably simple.

Sbabeld is most useful in cases (1) and (3).  It could in principle be
coerced into doing (2), but I'd recommend full babeld in that kind of
topology.

-- Juliusz