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Re: failure detection



On 14-aug-2005, at 16:49, Paul Jakma wrote:

An implementation that uses upper layer advice would only initiate a probe/reply sequence when the upper layer is unhappy.

This kind of thing worries me.

Apparently... I don't really get why, though.

Assuming it will be possible to have the upper layer 'direct' shim6 is assuming:

- OS maintainers will be prepared fundamentally change their network
  stacks to support shim6

Well, obviously they have to implement it or it won't work, no pain no gain. :-)


- Worse, assuming upper layers even /have/ a notion of being
  unhappy or happy.

I'm sure there will be ones that have such a notion and equally sure there are ones that don't.


Don't try get clever, cause the upper layer knows /more/ than shim6 does:

Just now you questioned whether the upper layer knows enough to be unhappy!


- It might have a list of addresses it wants to try, don't delay it

It doesn't. The application may have a list of addresses, but TCP or UDP only see a single one.


It is *much* better for the data-layer to signal *up*:

"sorry, it's unreachable"

as soon as it can, and let the transport or the application or maybe even the *user* get on with trying potential alternatives than for the data-layer to try aimlessly continue on for a significant period of time with complicated reachability tests.

So basically you're saying that applications can multihome better than the network stack? I disagree.