Subject: [Mip6] A question about the DAD protocol prototype

From: "Lee Garth" <[email-masked]>
Date: Tue, 06 Jan 2004 09:33:30 +0000

Dear:

    Having read the DAD sections in RFC2462, I have a question below:

    When a node(Node1) receives a NS sent from another node(Node2) who is 
performing DAD procedure, it proves that an address duplication is taking 
place. Then Node1 multicasts a NA with IP destination address set to 
FF02::1, advertising the duplication to the whole link. And then Node2 
discards the address it has just generated.
    Will the NA mentioned above affect the Neighbor Cache in all other 
neighbors on the link? How long after the NA is multicasted can the Node1 
use the address it has always been using? And how to manipulate the packets 
being transfered to and fro Node1 that would possibly have been sent awry?

    Thanks a million!

                                                                     Yours
                                                                          
Garthdawn
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From: Greg Daley <[email-masked]>
Date: Wed, 07 Jan 2004 10:05:16 +1100

Hi Lee,

Lee Garth wrote:
> performing DAD procedure, it proves that an address duplication is 
> taking place. Then Node1 multicasts a NA with IP destination address set 
> to FF02::1, advertising the duplication to the whole link. And then 
> Node2 discards the address it has just generated.
> neighbors on the link? How long after the NA is multicasted can the 
> Node1 use the address it has always been using? And how to manipulate 
> the packets being transfered to and fro Node1 that would possibly have 
> been sent awry?

Yes the Node1 NA overrides existing cache entries where they exist
(it has the override flag set).
In the case no existing cache entry existed, it is unlikely
to create new entries.

Since the DAD NS doesn't contain the Source Link Layer Address Option
(SLLAO), it doesn't make or modify any neighbor
cache entries (with RFC 2462 DAD).

The Owner of the address (Node1) can always use the address
(with no delay).

Only the tentative node must wait in DAD, and these nodes
do not NA while tentative.

Greg