(usagi-users 03425) Link-local address confusion

[Ignacy Gawedzki <Ignacy.Gawedzki@xxxxxx>]

Hi,

I have a very strange problem with a node that happens sort of not to
recognize a link-local address as its own.  The setup is very simple but I
have not yet discovered how the problem could be reproduced: two nodes on the
same link and one node (the source) pings the other (the destination).  Each
node have, in addition to an autoconfigured link-local address, a global
address on its interface.

After some time, one of the node's neighbor information about the other node
expires and a neighbor solicitation (NS) is sent, using the link-local address
as source and the unicast address of the neighbor as destination.  Then of
course the other node responds with a neighbor advertisement (NA) using its
global address as source and the link-local address of the other as
destination.  So far so good.  But then the node that sent the NS sort of
doesn't recognize the destination link-local address of the NA as its own, and
sends another NS with its link-local address as source and the special
multicast address as destination, just as if the destination of the packet was
another one's.  As this node is incapable of getting the NA of the other node
into account, the other node's entry in the neighbor table expires and the
ping eventually fails.

The only thing I can say about the configuration is that the interfaces are up
as the node is still configured as host (forwarding = 0, dad_transmits = 1,
autoconf = 1) and then is configured as router (forwarding = 1, dad_transmits
= 0, autoconf = 0, accept_ra = 0, accept_redirects = 0).

When this "lack of self recognition" thing happens, there is an entry for the
local link-local address in the node's neighbor table in "incomplete" state.
If I try to remove that entry manually, it changes to "failed" and the ping 
resumes, until the same scenario happens again.

Curiously enough, if I set the node as router before bringing the interface
up, this doesn't happen...

Is this, by any chance, a known problem?

-- 
P.S.  All information contained in the above letter is false,
      for reasons of military security.