Re: [DNA] DNAv6 Review from Mobopts

[JinHyeock Choi <jinchoe@gmail.com>]

Dear Bernard

thanks for your comments. glad to hear from you again.

> > The problem is that regular ND doesn't talk much about how to
> > determine if a host's existing address is still valid. As of my
> > knowledge, there are two ways in ND,
> > 1) check whether the prefix of the address is advertised in the
> > currently attached link.
> > 2) check whether an existing default router is still reachable.
> >
> > 1) gives a problem in multi-link subnets as you pointed out.
> > 2) gives a problem because of link-local scope of router address.
>
> For ND detection, you need to check the MAC address as well.  That way
> the existence of the same link-scope address on multiple links is not
> an issue.

It may cause some problem for DNA scheme to rely on MAC address as below.

First, in certain technology such as 802.16, MAC address is not used
for data transfer. In some implementation, when a host performs
address resolution to find the router's MAC address, its device driver
intercepts the message and provides a bogus MAC address.

Moreover, when a host moves to another subnet/ link, it won't speed up
DNA procedure to check whether its existing default router is still
reachable. So the scheme will give little help when, IMO, fast DNA is
needed the most, i.e. when a host doesn't have a valid address, so
should get a new one ASAP.

> > thanks for your sharing ideas with us. I wish you would also comment
> > on the existing simple DNA solution to facilitate its advancement.
>
> At first look, Simple DNA does not seem to have these issues because
> it can support fast reuse of DHCPv6-assigned addresses, and also because
> it can function even when no prefix is advertised in the RA.

I'll be happy that Simple DNA would do the job. I'll go over the draft
and comments on ML.

Thanks for your kind consideration.

Best Regards

JinHyeock