Re: [dna] Review of draft-ietf-dna-simple-11

"Bernard Aboba" <bernard_aboba@hotmail.com> Mon, 07 December 2009 16:35 UTC

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From: "Bernard Aboba" <bernard_aboba@hotmail.com>
To: "'Erik Nordmark'" <erik.nordmark@sun.com>
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Subject: Re: [dna] Review of draft-ietf-dna-simple-11
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Erik said: 

"Perhaps the reference to "STALE" is not clear above?
STALE refers to a state in RFC 4861 which implies that the host would 
trigger NUD sooner rather than later. If it isn't set to STALE then it 
might take up to 30 seconds more to detect that a router has gone dead. 
Thus a neighbor cache entry of STALE doesn't have anything to do with a 
routing table entry (unless the implementation is broken.)"

Since simple DNA involves sending out NS and RS packets, if the host
has a valid address on the network corresponding to the STALE entry,
it will effectively complete NUD as part of DNA.  Also, by sending
out the RS it will discover whether the router whose entry has 
been marked STALE is actually there or not.  

Given this, why would a host take 30 seconds to detect that a router
has gone dead?  Simple DNA should have completed (with a new default
router entry) long before that.