Re: [DNA-BOF] Draft charter now online

[Greg Daley <greg.daley@eng.monash.edu.au>]

Hi Spencer and JinHyeock,

CHOIJINHYEOCK wrote:
> Dear Spencer 
> 
> 
>>Re: choice of phrase, perhaps an "IP Network Attachment"?
> 
> 
> I guess that Attachment is better than Connection.  
>  
> 
>>Re: meaning of phrase, I'm still confused on where DNA is between
>>"send and receive IP packets with *any* other node" and "send and
>>receive IP packets with *at least one* other node". I've seen postings
>>saying that if we can only send IP packets to an authentication
>>server, we *are* connected/attached, and I've seen postings saying
>>that we *are not* connected/attached. Is this something we have
>>consensus on yet?
> 
> 
> You catch me at the weak spot. :-). I still don's have clear idea how
> we incorporate Authentication part into DNA work. 
> 
> IHMO, to be called attached, at least, a node should have a global IP 
> address, a default router and other per interface parameters in RA, 
> for example, link MTU, Reachable Time et cetra. 

I think that we have to be careful to distinguish between
the ability to send datagrams, and the configuration
being available in order to do so.

If we arrive on the same IP subnet which we have been
previously attached to (maybe a momentary disconnection),
then we already have enough configuration to transmit
to hosts within the link.  Additionally we already have
authentication configuration which allows us to transfer
data off the link.
(Although there are some difficult cases where not
all hosts on the subnet are reachable in from
another link-instance which is part of that subnet....)


In the case where we arrive on a new link-instance,
but we are unaware of the subnet to which we are attached,
we may not have valid global addresses, validated link-local
addresses or the capability to send data off the link.

I believe that our task is to determine that we've
arrived on a new link, with a new IP subnet so that
other processes can undertake the configuration.
This means (for example) that if we don't need to
configure the host's global address in DNA, then we
leave it to the subsystem which is responsible for
that (be it DHCPv6 or SAA).  I'd guess the same applies
to Authentication for off-link data transfer.

So I guess we have IP connectivity (the ability to
send and receive datagrams on the link, which I have been
calling Network Attachment) and IP configuration,
which entails appropriate Authentication, Addressing,
and Routing for the subnet.

My hunch is that the IP connectivity event (the network
attachment) comes when the wire is plugged into the host,
or the link-layer authentication is completed.

I'd guess that link-local communications in some form
are available by the end of the attachment detection phase
(although if RFC-2462 DAD or IPv4 is being used, this may
not be using a link-local unicast address...).

I'm not sure if this is the agreed viewpoint, but
one that I've been working with. (Tell me if it's not right).

Please indicate if we need to revise this, because
we'll need to provide enough information in the charter
to make sure people don't confuse our purposes.

Greg