[Olsr-dev] Patch Orgy Syncup

[Hannes Gredler]

On Thu, Aug 23, 2007 at 09:08:25PM +0200, Juliusz Chroboczek wrote:
| > | > b) Small Hysteresis on HNA4 0/0 to prevent routing flaps especially
| > | >    when ETX(a) slowly grows and ETX(b) slowly shrinks there is a 5
| > | >    minute "flaptime" for such a route.
| 
| > | Could you describe how that works?  I'm worried it might create
| > | routing loops.
| 
| > i share your concerns - there is one other protocol which uses
| > kind damping tequnique which is BGP. for exactly the same reason
| > (routing loops) it is prohibited to damp internal paths ...
| 
| It's slightly different.  BGP is a hierarchical protocol, and the
| prohibition of intra-AS flap damping is due to the requirement for
| routes to be consistent within the AS.
| 
| This doesn't apply to OLSR, which is a flat protocol.  The problem is
| that OLSR is a link-state protocol, and such protocols absolutely
| require that topology information and path computation be consistent

well the main difference is that BGP utilizes a distributed computation
and link-state protocols do local computation requiring synced databased.

either way:

 BGP with iBGP speakers preturbing the distributed computation 
   because of damping (read: bogus transient routes)

 and

 OLSR not installing its routes (in order to serve the hopbyhop
 routing paradigm) is semantically similar.

either way the net results is the same - routing and forwarding loops.

/hannes