[support] Why does HA do ndisc_do_dad action?

[Romain KUNTZ]

Hi,

On 2009/07/30, at 20:48, Arnaud Ebalard wrote:
> tony chen <aoc90058 at gmail.com> writes:
>
>> Hi everybody, I have a problem about DAD at HA.
>> When I go to the foreign network from home network,
>> I can find the DAD success message from the HA debug message.
>>
>> I feel confusing, why does the ha do the DAD action,
>> for what ??
>
> I would have to check the code but I think this is the default  
> behavior
> of the ND proxy code being activated for the MN that just registered
> with its HA from a foreign network.

Yes, upon the first registration of the MN, the HA sends a multicast  
NS on the Home Link to check if the MN's HoA is not already used on  
the link. If it does not get any NA reply after 1 sec (IIRC), it  
replies with a BA to the MN. This is what the "DAD succeeded" message  
means on the HA.

Cheers,
romain