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List:       ipng
Subject:    Re: draft-yhb-6man-nd-improvement-00
From:       "Yu Hua bing" <yhb810501 () gmail ! com>
Date:       2011-02-27 7:35:58
Message-ID: C06398DE202C4B1F92FA5F38049052C1 () yhbPC
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> It is far too easy for a node of the subnet to hijack an address by 
> spoofing
> the deleted flag...
Suppose host c sends a neighbor advertisement with flag D set to cheat all 
other nodes
that IPv6 address A assigned to host A is deleted,when host B receives the 
neighbor
advertisement,do as follows:
(1)If the target address is a unicast address in duplicate state on the
receiving interface, host B SHOULD set the state of the unicast
address to tentative and perform DAD.DAD will fail.
(2)If the source address is not the unspecified address, the neighbor
cache will be searched for the target's entry. If appropriate
neighbor cache entry has been located, because the neighbor is
unreachable, host B SHOULD delete the neighbor cache immediately.Host B can 
re-learn
the MAC address of host A via neighbor discovery protocol when it needs to 
communicate
with host A.

> Besides, nodes often learn that they're going off-link too late to send 
> the
> deletion notice anyway.
In some cases, for example, unplugging the network cables, nodes can't send 
the
deletion notice.But in other cases, it is helpful. 

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