Subject: RE: DHCPv6 address model proposal...

From: Bernie Volz <[email-masked]>
Date: Mon, 25 Sep 2000 06:50:50 -0400

Jim ... I think you have it. If the server's reply does not include an
address that the client previously had for that IA, the client should follow
the normal rules and continue using that address until the lifetimes expire.

This is just like stateless addrconf.

- Bernie Volz

-----Original Message-----
From: Jim Bound [mailto:[email-masked]]
Sent: Sunday, September 24, 2000 11:25 PM
To: DHCPv6 discussion list
Cc: [email-masked]
Subject: Re: DHCPv6 address model proposal...

>> But if the client still has time left to use that address the connection
>> should not be broken as I believe that stateless addrconf as a spec is
>> the architecture for that decision not ours.  So if a server wants to
>> stop a client from using an address that still has time left they should
>> have to send the address back to the client with a reduced lease to end
>> the connection and use of that address.

>It seems like what you are disputing is how the server notifies the
>client that an address must be dropped, not whether it can.   Am I
>right?   So what does this have to do with stateless address
>configuration?

Yes the issue is how.

In the existing IPv6 implementations and deployed IPv6 nodes when a
router provides a node with an address with valid and preferred
lifetimes, and then later sends another router advertisement but not
with prefixes previously sent.

Example Router Advertisement #1 (to be used for autoconfgiguration so
the A bit is set)

Prefix 44fe::/64
   Valid Lifetime 5 days
   Preferred Lifetime 4 days and 1400 hours 

Then Router Advertisement #2 is

Prefix 33fe::/64
   Valid Lifetime 5 hours
   Preferred Lifetime 3 hours 

When the second Router Advertisement #2 happens it has no affect to the
first Router Advertisement.  The only way the Router can stop use of the
44fe prefix is as follows:

Router Advertisement #3

Prefix 4ffe::/64
   Valid Lifetime 2 hours
   Preferred Lifetime 2 hours

IPv6 does not permit a router to send a zero lifetime unless IPsec is
being used with neighbor discovery.

So what I am stating is that if the server sends back a Reply and there
is no address in the packet which the client is still using and received
from DHCPv6 the client cannot break the IPv6 connections using that address 
per the rules defined in stateless addrconf.  The reason is that addrconf
has defined a behavior and we cannot break that with a stateful
protocol.  Basically stateless holds some rule over the architecture for
implementation.

regards,
/jim

---

From: Jim Bound <[email-masked]>
Date: Mon, 25 Sep 2000 11:34:33 -0400

>This is just like stateless addrconf.

Exactly.  We cannot break existing Ipv6 implementations either with
DHCPv6 or rebuild the stateless architecture at this point.
Not that anyone has proposed that but want to make sure  we as a group
understand any boundaries we have for IPv6.

regards,
/jim