Re: [RFC 4861] upper-layer reachability confirmation

Sebastien Roy wrote:
> On Tue, 2008-06-24 at 18:06 +0900, Yukiyo Akisada wrote:
>> I have a question about upper-layer reachability confirmation defined in RFC 4861.
>>
>> When the neighbor cache state for the default router is STALE
>> and the host sends a packet to off-link,
>> the default router sends redirect packet to the host.
>>
>> Can the host considers that the default router is REACHABLE?
>>
>> Personally, I didn't expected this behavior.
>> But I found that an implementation behaves like this
>> when I'm developping the conformance tester.
>>
>> How do you think about this behavior?
> 
> That seems reasonable to me.  The host sent a packet to the router, and
> the router responded with one of its own which was received by the host.
> This is bi-directional reachability.
> 

It's reasonable as long as the implementation doing so can correctly identify
that it sent the packet triggering the redirect.  If the implementation
can do so, it can assume bi-directional communication.

Personally, I wouldn't consider this upper layer indication, since Redirect
is not strictly upper layer.

-vlad
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