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Unidirectional Connectivity (was Re: review of draft-ietf-shim6-failure-detection-03.txt



El 26/06/2006, a las 13:13, Jari Arkko escribió:
On point b, I'm not sure there is a lot we can do. At least not
without revisiting some of the requirement decisions, such
as the need to support at least some scenarios where there's
only unidirectional connectivity.

Thoughts?

i guess that the main reason to support unidirectional connectivity is 
ingress filters.
I mean, as far as i understand, failures affecting only one of the 
directions in a path are kind of rare, so it probably the added 
complexity is not worth it. However, if no additional mechanisms for 
dealing with ingress filtering are availalable, I guess that 
unidirectional connectivity can be quite common.
Now, the solutions to deal with ingress filtering seem to also imply 
quite a few changes in the sites, and it is not so straight forward 
that sites would like that.
So i guess that the options are either complexity to deal with ingress 
filtering or complexity to deal with unidirectional paths...
OTOH, ingress filtering compatibility is also required for non-shim 
capable hosts within multihomed sites...
So, i think we should have at least the option to support 
unidirectional connectivity, but maybe we could define also a simpler 
protocol that only verifies bidirectional connectivity for those sites 
that do implement ingress filtering compatibility mechanisms
Regards, marcelo


--Jari