[Babel-users] Loop-freedom [was: emacs...]

[Juliusz Chroboczek]

>> do loop-free routing.

> Hah. :)

> I note that babel doesn't actually do that, any more.

Pick a pair (p, id), where p is a prefix and id is a router id.  Consider
the graph defined by all route table entries indexed by (p, id).  Then
Babel guarantees that at any time this graph is acyclic.

Since the union of multiple acyclic graphs is not in general acyclic,
Babel does not guarantee that the forwarding graph for a prefix p is
acyclic in the case where p is originated at different routers, although
it does guarantee that any loops disappear in linear time (with a constant
that depends on the amount of packet loss).  And of course Babel does not
guarantee loop-freedom in the presence of redistribution between protocols
(as in your case with DHCP).

-- Juliusz