Re: flow label demultiplexing

[Iljitsch van Beijnum <iljitsch@muada.com>]

On 19-apr-05, at 11:04, marcelo bagnulo braun wrote:

> In order to prevent flooding, i guess that the easiest way if to 
> preform a reachability test to the address, in order to find out if 
> the target is willing to receive packets.
> At this point, an interesting question is raised: do we need to 
> perform the reachability test in order to receive packets or is it 
> enough to perform the reachability test before sending packets to the 
> new locator?

I think for the security stuff it makes sense to delay the return 
routability check. On the other hand, we also have to worry about 
finding reasonably good paths and avoiding ingress filtering trouble. 
Doing an exhaustive search for the best locator pair at any point leads 
to excessive traffic (and delays), though. A good alternative could be 
to find a single working and/or good enough backup address pair after 
the initial shim startup exchange. In many cases this will allow fast 
failover to a working backup pair when there is an outage with only a 
relatively low amount of additional traffic.

Also, doing this for several associations allows a host to draw 
conclusions about its connectivity that can be helpful in selecting a 
more optimal first address to try both for regular sessions and for 
candidate backup pairs.